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Review

An Update Regarding the Bioactive Compound of Cereal By-Products: Health Benefits and Potential Applications

by
Anca Corina Fărcaș
1,*,†,
Sonia Ancuța Socaci
1,*,
Silvia Amalia Nemeș
2,†,
Oana Lelia Pop
1,
Teodora Emilia Coldea
3,
Melinda Fogarasi
3 and
Elena Suzana Biriș-Dorhoi
1
1
Department of Food Science, Faculty of Food Science and Technology, University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca, Manastur 3-5, 400372 Cluj-Napoca, Romania
2
Institute of Life Sciences, University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca, Manastur 3-5, 400372 Cluj-Napoca, Romania
3
Department of Food Engineering, Faculty of Food Science and Technology, University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca, Manastur 3-5, 400372 Cluj-Napoca, Romania
*
Authors to whom correspondence should be addressed.
These authors contributed equally to this work.
Nutrients 2022, 14(17), 3470; https://doi.org/10.3390/nu14173470
Submission received: 22 July 2022 / Revised: 20 August 2022 / Accepted: 21 August 2022 / Published: 24 August 2022

Abstract

:
Cereal processing generates around 12.9% of all food waste globally. Wheat bran, wheat germ, rice bran, rice germ, corn germ, corn bran, barley bran, and brewery spent grain are just a few examples of wastes that may be exploited to recover bioactive compounds. As a result, a long-term strategy for developing novel food products and ingredients is encouraged. High-value compounds like proteins, essential amino acids, essential fatty acids, ferulic acid, and other phenols, tocopherols, or β-glucans are found in cereal by-products. This review aims to provide a critical and comprehensive overview of current knowledge regarding the bioactive compounds recovered from cereal by-products, emphasizing their functional values and potential human health benefits.

1. Introduction

The European Union’s (EU) largest manufacturing sector is certainly the food and beverage industry [1]. Only biomass derived from food and feed crops, dedicated energy crops, trees, and agriculture residues now offers an accessible source for chemicals and products with the high added value among all known sustainable resources (solar, wind, geothermal) [2]. The main nutritionally exploitable wastes can be considered fruits and vegetables, meat and dairy, bakery, cereals and breweries, and aquaculture by-products [3,4].
Cereals and food grain cultivation and processing represent an important sector of the food industry [5,6,7]. Among cereals, rice, wheat, barley, and maize represent over 90% of cereal consumption [8]. However, the processing of these cereals generates significant amounts of by-products that, due to their chemical composition, deserve to be reintegrated into the circular bioeconomy system in a sustainable way (Figure 1). Barley, maize, millet, oats, rice, rye, sorghum, wheat wastes, and by-products contain a considerable amount of molecules with antioxidant properties [9] such as phenolic compounds, proteins [2,10], and bioactive peptides [11], but they also contain lipids [12], phytosterols [13], beta-glucans [14], vitamins, and minerals [15]. The recovered fractions can be used as a bioactive component in supplements, nutraceuticals, cosmetics, and pharmaceuticals, as well as food additives and other agricultural applications [16]. As a result, by-product management in the food industry can be considered a priority topic in terms of environmental protection and long-term sustainability. Even though industrial feedstock for biotechnological production of bioproducts can proficiently address the accumulation of environmental pollution caused by waste, detailed experimental trials are frequently required before scaling up the implementation due to economic factors [17]. Moreover, the bio-processing of cereal wastes into value-added products with higher functionality can reduce environmental pollution, minimize the requirement for agro-industrial waste treatment, and contribute to revenue diversification by covering multiple markets.
Overall, all the bioactive compounds recovered from cereal by-products and wastes must meet safety requirements, consumers’ acceptability, and fit into the circular bioeconomy system. In this regard, one of the most challenging decisions in isolating various bioactive components from cereal by-products is the compatibility of the matrix with extraction technologies, both from the point of view of recovery yield, purity, and the stability of the targeted compound, as well as economic feasibility and environmental impact. Other important aspects that require considerable attention are the process of reintegrating recovered compounds into functional foods, as well as ensuring the bioaccessibility and bioavailability of bioactive molecules in the human body [18,19]. Therefore, to maximize their action, improve their stability during processing and storage, protect them from unfavorable conditions, mask any unpleasant sensorial aspects, or have targeted delivery and a controlled release, different procedures can be applied before incorporation into food to solve these problems [20]. In this regard, several advanced encapsulation techniques such as spray/freeze drying, coacervation, ionic gelation, extrusion, fluidized bed coating, emulsification, and layer-by-layer deposition, have been developed and optimized in recent years [21].
As a result, this review aims to assess the recent information on the main bioactive and functional compounds recovered from cereal waste and by-products, their antioxidant, antimicrobial, and other important properties, emphasizing their functional value, applicability, and potential human health benefits.

2. Bioactive Compounds from Cereal Wastes and By-Products

2.1. Carbohydrates

Carbohydrates represent the major class of cereal constituents, being mostly composed of starch and soluble sugars but also non-digestible components (hemicellulose, cellulose, lignin, pectin, resistant starch, and other complex polysaccharides). More than 45% of the cereal bran content is made up of nonstarch polysaccharides, arabinoxylans, cellulose, fructans, beta-glucans, lignin, and its polymers, which are primarily found in the outer layer of cereals. Therefore, cereal by-products can be successfully exploited as low-cost alternatives for extracting various carbohydrates fraction with multiple potential applications for both the pharmaceutical and food industry [22,23].
The physical characteristics of dietary fibers, such as particle size, swelling and water retention capacity, water solubility, and viscosity, have a major impact on the nutritive, physiological, and technological characteristics of food, such as texture, rheology, and sensory perception [24,25]. Moreover, dietary fibers are known to have health benefits that include lowering glycemic response, controlling blood cholesterol levels, improving antioxidant activity, promoting weight loss, and enhancing the microbiota population in the small intestine and colon [26,27,28,29]. For example, arabinoxylans, recognized for their prebiotic effects on obesity [30] and other metabolic improvements [31] (e.g., the ability to lower blood cholesterol and postprandial glycemic response), represent 10.9–26.0% of the dry matter of bran [32]. The European Food Safety Authority (EFSA) acknowledged and approved in 2011 the health claim regarding the capacity of wheat arabinoxylans to reduce blood glucose levels after a meal [33].
In a recent study, Malunga and collab., suggest that antiglycemic properties of arabinoxylans extracted from wheat aleurone and bran may be derived from direct inhibition of α-glucosidase activity [34]. A similar observation was also concluded by Boll and collab., who tested the impact of bread containing a mix of arabinoxylan extracted from wheat bran and maize resistant starch, also reporting the positive influence on blood glucose response in rats and human trials [35]. It is also well known that cereal and other vegetable fiber possess a higher laxative effect compared to fiber from fruits [36]. For example, beta-glucans have the ability to prolong postprandial satiety, increased stool mass, and relieve constipation [36,37]. Similar effects were observed by Nguyen and collab., who concluded that corn bran arabinoxylans consumption had a positive effect on bowel movement and fecal consistencies [38]. Furthermore, they are recognized for their prebiotic effect and good capability to develop good colonic microbiota [39], which contribute to the production of several bioactive postbiotics, such as exopolysaccharides (EPS, e.g., dextrans, levans, fructans, and reuterans), and reduce the growth of deleterious microorganisms.
Out of the main representative cereal by-products, brewer’s spent grain (BSG) represents an important source of carbohydrates that remains unexploited in the brewing process [40,41]. With ca. 85% of the total generated by-products, BSG is mostly composed of non-starch polysaccharides (approximately 50% of dry BSG) but also contains various ratios of residual undigested starch (1.3–10%) [22]. The non-starch polysaccharides of BSG are mainly made of cellulose (15.1–25%), hemicellulose (24.8–40%), and lignin (7–28%), amounts which depend on grain cultivar and quality, adjuncts added, and conditions and efficiency of the steps involved in the brewing process. Hemicellulose, which includes xylan, glucuronoxylan, arabinoxylan, glucomannan, and xyloglucan, belongs to a group of heterogeneous polysaccharides that help the strengthening of the cell wall by interacting with cellulose and/or lignin. Commonly found in hemicellulose are glucose, xylose, mannose, galactose, rhamnose, and arabinose [42].
Regarding the presence of beta-glucans in the biomass of BSG, the values are relatively low (0.4–1.1% dry mass) due to the extensive degradation caused by processing [43]. Additionally, the malting and mashing procedures change the molar mass, molar mass distribution, and solubility of beta-glucans, partially altering their physicochemical and technical properties.
Arabinoxylans, the main structural polysaccharides of cell walls, represent the major part of hemicelluloses present in BSG (22.2% of the dry material). Due to this aspect, many studies have analyzed their impact on human health, reporting a series of potential beneficial effects such as improving cholesterol metabolism, regulating intestinal transit, inhibiting pathogenic bacteria, and reducing the postprandial glycemic response [44]. In a recent study, Lynch and collab., investigated the microbiome modulating potential of BSG with a focus on the prebiotic potential of the extracted arabinoxylans. As a result, they concluded that the tested arabinoxylans positively influenced the fecal microbiota due to bifidogenic effects [45].
As already specified in the previous examples, wheat bran is another by-product with proven beneficial effects on human health [46]. This fraction represents a sustainable source of both soluble and insoluble dietary fiber that can be converted into beta-glucans and arabinoxylans, as well as digestible carbohydrates that can be converted into starch, glucose, lactic acid, succinic acid, and/or ethanol.These complex characteristics expand its applicability as a source of valuable compounds for the food, cosmetic and pharmaceutical industries. Defatted wheat germ is also a good source of fiber, pentosans, and sugars (of which about 20% are sucrose and raffinose, respectively) [47].
Fermented wheat germ extract has been promoted to contain a range of bioactive molecules that promote positive effects in cancer prevention. Therefore, in a recent study, Kon and collab., discover that ethanolic extract of fermented wheat germ with yeast extract inhibits human ovarian cancer cell growth in a dose-dependent manner [48].
Regarding the dietary fibers found in rye, they are composed of arabinoxylans, beta-glucans, cellulose, fructan, and Klason lignin, with arabinoxylans serving as the cereal’s predominate chemical constituent. Rye has several health advantages, including a lower risk of diabetes, cardiovascular disease, and several malignancies. This by-product was shown to contain more beta-glucans and fructans (4.3–5.3%, and 6.6–7.2%, respectively) than wheat bran (2.2–2.6%, 2.8–3.7%, respectively), while the amount of cellulose (5.5–6.5%) was nearly two times lower (9.3–12.1%) [48,49]. On the other hand, the most significant source of beta-glucans is not rye, oat, and barley exhibiting higher amounts [47]. Prykhodko and collab., carried out an experimental protocol through which they proposed to highlight the influence of rye kernel base bread on gut microbiota and metabolic response. They suggested that the effect of increasing gut fermentation had a positive influence on improving both the glucose response and appetite control by maintaining satiety feelings for a long period [50].
Beta-glucans account for at least 5.5% of the dry matter and about 16.0% of the total dietary fiber in oat bran, being considered among its most important constituents. Furthermore, oat bran can have its beta-glucan content increased by 1.3 to 1.7 times over whole grain by successively dry milling and sifting the grain [51]. According to Xu and collab., oats-derived beta-glucan exhibited prebiotic activity and modulate gut microbiota increasing bifidobacteria as well as acetate and propionate productions and highlighting the potential cholesterol reduction effect [52].
As previously mentioned, the recent increased interest in consuming barley-based products comes from its high content in beta-glucans [32], which along with other phytochemicals offer antioxidant, antiproliferative, glycemic index, blood sugar, and LDL cholesterol lowering, and immune-modulating effects. Due to their increased resistance to digestion and prebiotic properties, gelation characteristics, and fermentative formation of short-chain fatty acids (SCFA) such as acetate, propionate, and butyrate, a preventive role against colorectal cancer was also observed [53,54]. Even though the use of beta-glucans in pharmacology is an interesting perspective, it still has limited applicability caused by the processing costs that accompany the extraction, purification, and standardization difficulties, therefore it requires more optimization to become sustainable.
As a first conclusion, it is well known that products like white rice grain, and in general dehulled cereals, contain fewer bioactive compounds in comparison to bran by-products due to the processing technology applied [37]. Despite that, the integration of grain by-products in food consumption represents a challenging procedure due to the generally lower sensory acceptance [39]. In order to reduce these inconveniences, the most recent advances in extraction, thermal treatments, extrusion, enzymatic treatment, and fermentation allow significant improvements both in terms of chemical and sensory properties, as well as the bioavailability of nutrients and overall quality of the final products [40,41,42,43,46,47].
Recently, many studies showed the value-added potential of cereal by-products carbohydrates. They mostly include applications in the food, feed, pharma, and packaging industries (Table 1).

2.2. Proteins and Amino Acids from Cereal Waste and By-Products

Proteins are one of the key components required for cell growth and repair mechanisms in our body, being essential for human nutrition. In the assessment and selection of proteins based on their quality, it is important to consider the digestibility, the amino acid profile, and the presence of antinutritive compounds besides the total protein content of raw materials [58]. Recently, food processing by-products have gained certain attention, among which, cereal-related by-products have become very attractive considering that they can be an economical source of important compounds like minerals, antioxidants (such as polyphenols and vitamins), dietary fibers, proteins, carbohydrates, and sugars [22]. As a result, many researchers present a keen interest in valorizing cereal by-products as protein sources, creating a feasible option to produce and ensure a sustainable protein source for the global demand [59]. There are several industrial-scale cereal by-products with high protein content and among these, brewer’s spent grain, rice bran, wheat bran, and corn bran proved to be excellent raw materials for producing hydrolysates with potential biological activity. Numerous studies published in the literature underline the possibility of obtaining peptides from brewer’s spent grain and rice bran protein having bioactive properties, highlighting the high-value potential protein extracted from these by-products [60,61]. Bioactive peptides are made of 2–50 amino acids that impact human health and food products [62,63]. They are classified into endogenous, and exogenous peptides (both obtained by enzymatic hydrolysis) [64]. The bioactive peptides are absorbed in the intestine and, from there, are transported through into the blood circulation.
The conversion of carbohydrates during alcoholic fermentation lowers the mass of grain leading to the increase of the amino acid content of cereal by-products which was determined to be between 30% and 85% of total protein [65,66]. In general, the proteins found in cereal by-products are classified based on their solubilities. Albumins are water soluble, globulins are soluble in salts, glutenins dissolve in alkaline solutions, and prolamins in different concentrations of alcoholic solutions. Prolamin-type proteins are present in the main cereals’ by-products (corn, wheat, sorghum, and barley by-products) and constitute around 80% of the total protein. Several research groups around the world target prolamin functionalization by extortion from cereal by-products [65].
From a biological point of view, the high essential amino acid content confers to bran proteins a higher nutritional value because these proteins play an important role during seed germination. On the other hand, cereals and cereal by-products have a variable amino acid content, depending on several factors such as plant variety or external environmental conditions [22]. In addition, it is well known that temperature rise during milling can affect the quality of proteins, but if the milling process does not generate large amounts of heat, protein denaturation can be avoided. Opposite, the proteins in brewer’s spent grains or dried distiller’s grains can be partially subjected to degradation, aggregation, or even denaturation and, in some instances, can be used as amino acids or nitrogen (N) sources. Considering the importance of these cereal-related proteins, several studies in the literature focus on the development of efficient extraction methods. Among these methods, extraction in alkaline conditions linked with isoelectric precipitation has been the most applied technique (Table 2). Due to their high protein content, the cereal’s by-products presented in Table 2 can be processed and exploited to obtain different functional ingredients/products.

2.3. Vitamins and Mineral Microelements from Cereal Wastes

Human and animal bodies require an optimal nutritional balance. According to existing research, human metabolism requires 49 essential nutrients to maintain health and wellbeing, including 16 mineral microelements and 13 vitamins [81,82,83]. Cereal waste and by-products are a valuable source of vitamins and microelements. The majority of micronutrients are present in bran, especially in the aleurone layer, and in cereal germs [15]. According to the requirements of the human body, the mineral elements contained in cereals and cereal by-products substrate are grouped into two categories: macrominerals (Ca, Mg, K, Na, Cl, P, and S) and oligo-minerals (I, Zn, Se, Fe, Mn, Cu, Co, Mo, F and B) [84]. The cereal by-product minerals concentration is between 6.6–9.9%. Along with the mineral content, cereal by-products have relevant amounts of B vitamins, such as niacin, pantothenic acid, biotin, thiamin, and riboflavin [15,85]. BSG, the most common cereal by-product of the beer industry, is a rich source of carbohydrates, proteins, lipids, and smaller amounts of minerals, vitamins, and phenolic compounds [86]. The main mineral elements identified in the BSG are Phosphorus (6 × 103 mg·kg−1), Calcium (3 × 103 mg·kg−1), Sulphur (2.9 × 103 mg·kg−1), Magnesium (1.9 × 103 mg·kg−1), and smaller amounts of Potassium, Iron, Sodium, and Zinc. The primary vitamin contained by BSG is Choline (1.8 × 103 mg·kg−1), followed by reduced amounts of Niacin, Pantothenic acid, Riboflavin, and Thiamine [86]. A proper selection of the applied processes must be made to facilitate the effective recovery of bioactive compounds from the biomass for maximized utilization of the functional compounds from the BSG. The most often performed techniques attempt to convert the primary fibers of BSG, including cellulose and hemicellulose, into fermentable sugars by chemical and enzymatic hydrolysis releasing the functional compounds bound to the lignocellulosic chain [86]. Extraction methods and certain pre-treatments applied to cereal waste and by-products can significantly increase the yield of vitamins and minerals. According to Tuncel and collab., a considerable increase in B vitamins and mineral elements was observed after integrating rice bran into bread. The bread’s Zinc (Zn), iron (Fe), potassium (K), and phosphorus (P) contents progressively increased with the addition of stabilized rice bran, while the niacin content was increased by 10% [85].
Regarding the occurrence of microelements in cereal by-products and wastes resulting from the cereal processing industry, it should be mentioned that the soil mineral nutrients concentration is the crucial factor that influences the bran minerals content [85]. Moreover, the concentration of phytic acid in the waste substrate affects the bioavailability of mineral elements in cereal by-products. Phytic acid is mostly concentrated in the bran and is considered an anti-nutritional factor [15]. The large charges acquired in the gastrointestinal environment result in the formation of a stable phytate complex that inhibits the action of phytase enzymes. In some circumstances, phytic acid forms protein linkages and inhibits α-amylase activity, resulting in lower starch digestibility [87]. Processing approaches connected to increasing nutritional qualities and sensory aspects are being developed to boost the functional food value and minimize the anti-nutritional activity of cereal by-products and waste. Phytase using, soaking, germination, fermentation, boiling, extrusion, dehulling, radiation, ultrasonic waves, and storage are among the most recent approaches used to remove the phosphorus reserve in cereal by-products and waste [88].
However, different secondary metabolites, minerals, and vitamins have been extracted from cereal waste and by-products, using various approaches. These techniques might provide an alternative strategy to expand the production of bioactive compounds for use as nutraceuticals or as components in the development of functional foods in the near future.

2.4. Lipids from Cereal Wastes

The lipid content of cereal by-products (Table 3) is mainly associated with the specific characteristics of the biomass, such as the cultivars/varieties/species of grains, bran particle size, the oil recovery conditions, and the method of extraction, type of extraction solvent, time and temperature. In many matrices, some of the fatty acids are bound through lipid-protein or lipid-starch intermolecular bonds, and the process of acid hydrolysis is applied for releasing these lipid compounds [89,90]. Lipids are mainly found in the bran layer and wheat germ. According to Górnaś and collab., rice bran was identified as having the major lipid content yield (189 g kg−1 dw), followed by wheat germ (112 g kg−1 dw), corn bran (74 g kg−1 dw), oat bran (58 g kg−1 dw), buckwheat bran (41 g kg−1 dw), spelt bran (39 g kg−1 dw), wheat bran (33 g kg−1 dw) and rye bran (27 g kg−1 dw) [89].
Rice lipids include unsaturated fatty acids, particularly oleic acid (45%) and linoleic acid (33%), and polyunsaturated fatty acids, such as omega-3 and omega-6, with functional properties for human health [91,92]. Rice bran’s biologically active fatty acids, along with other functional compounds like tocopherols and tocotrienols, squalene, phytosterols, polyphenols, and gamma-oryzanol, are responsible for antioxidant and anti-inflammatory activities, as well as preventing cardiovascular diseases, atherosclerosis, and hyperlipidemia [91]. Because of its high lipid content, rice bran’s functional compounds and sensory qualities may be affected by the rapid process of bran oxidation. Lipases and lipoxygenase activity intensifies the lipid oxidation process, due to the accelerated activity throughout storage [90]. For that reason, certain treatments are required to avoid natural fatty acid degradation.
Wheat germ is a byproduct of the milling process, and approximately 25 million tons of wheat germ are generated globally each year [90]. Wheat germ is a valuable by-product rich in high-value nutrients, including biopeptides, polyunsaturated fatty acids (Table 3), and functional compounds such as sterols, tocopherols, tocotrienols, phenols, and carotenoids. Therefore, wheat germ oil decreases its value after 15 days due to intense enzymatic activity that causes oxidative damage to the fatty acids compounds [93]. In addition to wheat germ, a high lipid content is also found in rice germ (25%), corn germ (9–50%), and soybean germ (4–24%) [94].
By-products from the beer industry include wasted grains, hops/tubs, and yeast. Brewers’ spent grains are the most common, accounting for 85% of brewing by-products [84,95]. The majority of BSG samples are lignocellulosic materials based on whole-grain and malt kernels, which contain fibers (50–70%), starch (1–12%) proteins (15–25%), lipids (7–10%), and ash (2–5%) [84]. Triglycerides (25,300 mg/kg), free fatty acids (6710 mg/kg), and minor quantities of monoglycerides (610 mg/kg) and diglycerides (2880 mg/kg) constitute the majority of BSG lipids (Table 3). Lower amounts of steroid molecules, such as steroid hydrocarbons, steroid ketones, free sterols, sterol esters, and sterol glycosides, were also reported [96]. Special pretreatments and bioprocesses applied on BSG can increase the lipid content of this substrate. Patel and colleagues pretreated BSG with microwave-assisted alkaline and organosolv pretreatments, followed by Rhodosporidium toruloides yeast fermentation for the production of microbial lipids. Following the pretreatments and the fermentation bioprocess applied, a profile of fatty acids similar to common vegetable oils was obtained. This integrated technique may be utilized to obtain biodiesel raw materials based on BSG [95]. Moreover, BSG bioactive lipids might be seen as a valuable source of fatty acids, triglycerides, and phytosterols, considering that these compounds have a wide range of functional properties and are of interest to the industrial sectors, such as nutraceuticals, pharmaceuticals, cosmetics, food, and food supplements [12,13,97]. Table 3 shows the majority of the lipid content in a variety of by-products and cereal waste.
Table 3. Fatty acid composition of cereal by-products and waste.
Table 3. Fatty acid composition of cereal by-products and waste.
Cereal
By-Product/Waste
Fatty AcidConcentration
(% of Total Lipids)
Extraction MethodsFunctional PropertiesReference
Rice branTriacylglycerol60.12Solvent extraction (n-hexane)Balanced fatty acid profile;
Delicate flavor;
High smoke point;
High bioactive ingredient.
[92,98]
Polyunsaturated fatty acids40.73
Linoleic acid38.84
Oleic acid34.31
Palmitic acid19.87
Free fatty acids29.69
Diacylglycerol9.98
Monoacylglycerol0.21
γ-oryzanol18.53
Phytosterol22.40
Wheat germLinoleic acid57Solvent extraction (hexane)Food ingredients with potential health benefits.[93]
Palmitic acid17.5
Oleic acid15
Linolenic acid6
Total polyunsaturated fatty acids64.5–63.7
Brewer’s spent grainFree fatty acids18Soxhlet acetone extraction;
Hot water extraction;
Sulfuric acid hydrolysis;
Alkali extraction
Nutraceutical, pharmaceutical, and cosmetic properties.[96]
Triglycerides67
Monoglycerides1.7
Diglycerides7.7
Steroid compounds5
Oat branOleic acid44.09–46.68Subcritical butane extractionPreventive effects on cardiovascular disease and development of atherosclerosis;
Reducing body fat.
[99]
Linoleic acid32.54–32.88
Stearic acid1.71–1.89
Palmitic acid15.68–16.03
Corn germPalmitic acid11.57Pressing extractionCommercial shortening replacement in food industries.[100]
Stearic acid2.89
Oleic acid29.45
Linoleic acid54.31
Rye branLinoleic acid61.09Supercritical carbon dioxide extraction using response surface methodologyFood grade ingredient.[101]
Palmitic acid13.74
Oleic acid13.65
Linolenic acid6.37
Corn wastePalmitic acid23.0 Solvent extraction analyzed by gas chromatography (Folch method)Feed or pharmaceutical industry.[102]
Stearic acid3.4
Oleic acid11.7
Linoleic acid52.9
α-Linolenic acid5.3

3. Compounds with Antioxidant Properties from Cereal By-Products

Cereal waste and by-products recovered compounds are widely used in the food industry (additives for prolonging food products’ shelf life) [63,103,104], cosmetics [105,106], phytopharmaceutical and health products (food supplements, nutraceuticals, adjuvants in therapies) [64,107] mainly due to their biological activities.
An antioxidant is a chemical that can slow or stop oxidation or oxidative cell damage caused by oxidants [8]. Antioxidants can disrupt the oxidation chain by stabilizing themselves via chemical structure resonance. Molecules can act as antioxidants by interacting with transcription factors [108]. Human’s most common diseases, such as cancer, diabetes, and cardiovascular or neurological problems, have all been linked to oxidative stress [107]. Moreover, food degradation and lipid oxidation have also been attributed to oxidative stress [104], all being improved by the presence of antioxidant compounds. Natural antioxidants are primarily found in vegetal sources [109]. Studies revealed that antioxidants, such as terpenes, phenols, phytosterols, and bioactive peptides, from cereal wastes, may be extracted by different methods and may be further utilized in various applications as shown in Table 4. Furthermore, cereal by-products are reported to be used as a substrate for bacteria or by fungi able or engineered to produce antioxidants [110].
As can be seen in Table 4, most of the cereal waste antioxidants refer to phenolic compounds. Proteins and peptides can also have antioxidant activities, adding them to food matrices delaying the process of lipid oxidation [123]. According to Stefanello and collab., the samples defatting negatively influence the phenolic content and the antioxidant activity (except for the corn silage). They used microwave-assisted extraction methods to determine the total phenolic content of brewer’s spent grain, corn silage, rice, corn, and wheat brans, using three different solvents (acetone, methanol, and aqueous NaOH 0.75% v/v) [124]. Another study found that using lactic acid and specific amino acids could have a significant impact on total polyphenols and antioxidant activity yield [125]. Although studies regarding the bioactive peptides isolated from cereal wastes are scattered, most experimental protocols also highlight their antioxidant potential. Thus, several other activities of bioactive peptides are being tested. Ilhan-Ayisig and his colleagues proved a cytotoxic effect on the MDA-MB-231 estrogen-independent breast cancer cell line when treated with bioactive peptides derived from rice husk. Notable is that the nonencapsulated form of the peptides has proven anticancer potential (IC50 values of >100 μg/mL for all formulations in normal cell line VERO) [11]. In another study, non-alcoholic steatohepatitis was ameliorated in mice by upregulating the AMPK/ACC signaling pathway. The mice were given leucine-arginine-proline and leucine-glutamine-proline (from wheat bran) in water solutions (0.05 and 0.20%) for 10 weeks [120]. These leucines may impact the modulation of insulin sensibility [126].
Over the antioxidant activity, the cereal waste recovered compounds also present anticancer, antidiabetic, anti-inflammatory, or antimicrobial functions [109,114,115,116]. Wheat bran oil proved antibacterial activities against pathogenic bacteria such as Escherichia coli, Pseudomonasaeruginosa, Bacillus subtilis, and Staphylococcus aureus and some fungi such as Candida albicans and Aspergillus niger [127]. Furthermore, free phenolics extracted from wheat bran using ultrasound-assisted extraction, as well as bound phenolics extracted using alkaline hydrolysis and ultrasound-assisted alkaline hydrolysis, expressed antimicrobial activity against Staphylococcus aureus and Staphylococcus epidermidis strains [115]. BSG extracts integrated into biofilms showed antimicrobial activity against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria, as well as antifungal efficacy against the polymorphic fungus Candida albicans [128].
Anti-inflammatory plant-derived bioactive chemicals are also in high demand. Immunomodulatory substances impact the immune system’s reaction to various distressing factors, either favorably or unfavorably. Inflammation is at the root of many medical illnesses, including Parkinson’s disease, Alzheimer’s disease, dementia, multiple sclerosis, and autoimmune diseases [129,130]. The anti-inflammatory activity of eight phenolic compounds isolated from BSG (pale and black) was investigated. The results demonstrated that phenolic extracts of BSG, particularly pale BSG extracts, can inhibit the stimulated production of cytokines (particularly interleukin-2, interleukin-4, and interleukin-10) and protect against cellular oxidative stress [130]. In addition, McCarthy and colleagues successfully proved the antioxidant and anti-inflammatory action of protein hydrolysates derived from BSG [131]. Furthermore, wheat bran ingestion lowered the inflammatory effect on the liver. The size of the ingested particles impacted the lowering of hepatic and systemic inflammatory indicators following high sugar (fructose) consumption, varying the activity of the inflammatory intestinal barriers.
As a result, cereal by-products can be considered sustainable sources of bioactive compounds and secondary metabolites with multiple functionalities, therefore their incorporation into functional foods, supplements, and pharmaceutical products is a research field that requires increased attention.

4. Conclusions

Cereal waste and by-products generated during cereal processing include bran, husk, germ, hops, hulls, and brewer’s spent grain components, which can be collected and valorized under a circular economy strategy. These by-products contain a variety of high-value compounds, mainly bioactive compounds with significant health benefits. They can be exploited as food ingredients, supplements, additives, or extracts that are high in functional molecules and micronutrients, such as phenolic compounds, novel carbohydrates, carotenoids, biopeptides, bioactive fatty acids, amino acids, prebiotics, vitamins, and mineral elements. Bioactive compounds derived from cereal waste and by-products can be used as antioxidants and preservatives, reducing lipid oxidation and microbial growth. As a result, bioactive compounds derived from cereal by-products can increase the product shelf-life, with potential applications in the food additives, cosmetic and pharmacology industries, animal products, dairy products, beverages, and bakery products industries. Furthermore, processing technologies designed to improve nutritional characteristics and sensory features are being developed to increase the functional food value, and nutrients bioavailability, while reducing the anti-nutritional factors of cereal by-products and waste. In the near future, more studies are necessary on the extraction procedures in order to provide a sustainable strategy for increasing the production of bioactive compounds for use as nutraceuticals or as ingredients in the development of functional products.

Author Contributions

Conceptualization, A.C.F., S.A.N. and S.A.S.; software, A.C.F. and S.A.N.; validation, A.C.F. and S.A.S.; writing—original draft preparation, T.E.C., O.L.P., E.S.B.-D., M.F. and S.A.N.; writing—review and editing, A.C.F., S.A.N. and S.A.S.; supervision, A.C.F. and S.A.S.; project administration, A.C.F.; funding acquisition, A.C.F. All authors have read and agreed to the published version of the manuscript.

Funding

This work was supported by a grant of the Romanian Ministry of Education and Research, CCCDI-UEFISCDI, project number PN-III-P2-2.1-PED-2019-3622, within PNCDI III.

Acknowledgments

Special thanks to the implementation team of the project PN-III-P2-2.1-PED-2019-3622.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Siracusa, L.; Ruberto, G. Not only what is food is good—Polyphenols from edible and nonedible vegetable waste. In Polyphenols in Plants; Elsevier: Amsterdam, The Netherlands, 2019; pp. 3–21. [Google Scholar]
  2. Ng, H.S.; Kee, P.E.; Yim, H.S.; Chen, P.-T.; Wei, Y.-H.; Lan, J.C.-W. Recent advances on the sustainable approaches for conversion and reutilization of food wastes to valuable bioproducts. Bioresour. Technol. 2020, 302, 122889. [Google Scholar] [CrossRef]
  3. Patel, S.; Shukla, S. Fermentation of food wastes for generation of nutraceuticals and supplements. In Fermented Foods in Health and Disease Prevention; Elsevier: Amsterdam, The Netherlands, 2017; pp. 707–734. [Google Scholar]
  4. Pop, C.; Suharoschi, R.; Pop, O.L. Dietary fiber and prebiotic compounds in fruits and vegetables food waste. Sustainability 2021, 13, 7219. [Google Scholar] [CrossRef]
  5. Schwan, R.F.; Ramos, C.L. Functional beverages from cereals. In Functional and Medicinal Beverages; Elsevier: Amsterdam, The Netherlands, 2019; pp. 351–379. [Google Scholar]
  6. Román, G.; Jackson, R.; Gadhia, R.; Román, A.; Reis, J. Mediterranean diet: The role of long-chain ω-3 fatty acids in fish; polyphenols in fruits, vegetables, cereals, coffee, tea, cacao and wine; probiotics and vitamins in prevention of stroke, age-related cognitive decline, and Alzheimer disease. Rev. Neurol. 2019, 175, 724–741. [Google Scholar] [CrossRef]
  7. Sofi, F.; Dinu, M.; Pagliai, G.; Cei, L.; Sacchi, G.; Benedettelli, S.; Stefani, G.; Gagliardi, E.; Tosi, P.; Bocci, R. Health and nutrition studies related to cereal biodiversity: A participatory multi-actor literature review approach. Nutrients 2018, 10, 1207. [Google Scholar] [CrossRef] [Green Version]
  8. Akanbi, T.O.; Dare, K.O.; Aryee, A.N. High-Value Products from Cereal, Nuts, Fruits, and Vegetables Wastes. In Byproducts from Agriculture and Fisheries: Adding Value for Food, Feed, Pharma, and Fuels; Wiley: Hoboken, NJ, USA, 2019; pp. 347–368. [Google Scholar]
  9. Fărcaș, A.; Drețcanu, G.; Pop, T.D.; Enaru, B.; Socaci, S.; Diaconeasa, Z. Cereal Processing By-Products as Rich Sources of Phenolic Compounds and Their Potential Bioactivities. Nutrients 2021, 13, 3934. [Google Scholar] [CrossRef]
  10. Poutanen, K.S.; Kårlund, A.O.; Gómez-Gallego, C.; Johansson, D.P.; Scheers, N.M.; Marklinder, I.M.; Eriksen, A.K.; Silventoinen, P.C.; Nordlund, E.; Sozer, N.; et al. Grains—A major source of sustainable protein for health. Nutr. Rev. 2022, 80, 1648–1663. [Google Scholar] [CrossRef]
  11. Ilhan-Ayisigi, E.; Budak, G.; Celiktas, M.S.; Sevimli-Gur, C.; Yesil-Celiktas, O. Anticancer activities of bioactive peptides derived from rice husk both in free and encapsulated form in chitosan. J. Ind. Eng. Chem. 2021, 103, 381–391. [Google Scholar] [CrossRef]
  12. Kyriakidou, Y.; Wood, C.; Ferrier, C.; Dolci, A.; Elliott, B. The effect of Omega-3 polyunsaturated fatty acid supplementation on exercise-induced muscle damage. J. Int. Soc. Sports Nutr. 2021, 18, 9. [Google Scholar] [CrossRef]
  13. Oliveira Godoy Ilha, A.; Sutti Nunes, V.; Silva Afonso, M.; Regina Nakandakare, E.; da Silva Ferreira, G.; de Paula Assis Bombo, R.; Rodrigues Giorgi, R.; Marcondes Machado, R.; Carlos Rocha Quintão, E.; Lottenberg, A.M. Phytosterols Supplementation Reduces Endothelin-1 Plasma Concentration in Moderately Hypercholesterolemic Individuals Independently of Their Cholesterol-Lowering Properties. Nutrients 2020, 12, 1507. [Google Scholar] [CrossRef]
  14. Arzami, A.N.; Ho, T.M.; Mikkonen, K.S. Valorization of cereal by-product hemicelluloses: Fractionation and purity considerations. Food Res. Int. 2022, 151, 110818. [Google Scholar] [CrossRef]
  15. Verni, M.; Rizzello, C.G.; Coda, R. Fermentation Biotechnology Applied to Cereal Industry By-Products: Nutritional and Functional Insights. Front. Nutr. 2019, 6, 42. [Google Scholar] [CrossRef] [Green Version]
  16. Ma, T.; Hu, X.; Lu, S.; Liao, X.; Song, Y.; Hu, X. Nanocellulose: A promising green treasure from food wastes to available food materials. Crit. Rev. Food Sci. Nutr. 2020, 62, 1–14. [Google Scholar] [CrossRef]
  17. Belc, N.; Mustatea, G.; Apostol, L.; Iorga, S.; Vlăduţ, V.-N.; Mosoiu, C. Cereal supply chain waste in the context of circular economy. In Proceedings of the E3S Web of Conferences, Villeurbanne, France, 20 August 2019; p. 03031. [Google Scholar]
  18. Zduńczyk, Z.; Flis, M.; Zieliński, H.; Wróblewska, M.; Antoszkiewicz, Z.; Juśkiewicz, J. In vitro antioxidant activities of barley, husked oat, naked oat, triticale, and buckwheat wastes and their influence on the growth and biomarkers of antioxidant status in rats. J. Agric. Food Chem. 2006, 54, 4168–4175. [Google Scholar] [CrossRef]
  19. Sagar, N.A.; Pareek, S.; Sharma, S.; Yahia, E.M.; Lobo, M.G. Fruit and vegetable waste: Bioactive compounds, their extraction, and possible utilization. Compr. Rev. Food Sci. Food Saf. 2018, 17, 512–531. [Google Scholar] [CrossRef] [Green Version]
  20. Mehta, N.; Kumar, P.; Verma, A.K.; Umaraw, P.; Kumar, Y.; Malav, O.P.; Sazili, A.Q.; Domínguez, R.; Lorenzo, J.M. Microencapsulation as a Noble Technique for the Application of Bioactive Compounds in the Food Industry: A Comprehensive Review. Appl. Sci. 2022, 12, 1424. [Google Scholar] [CrossRef]
  21. Choudhury, N.; Meghwal, M.; Das, K. Microencapsulation: An overview on concepts, methods, properties and applications in foods. Food Front. 2021, 2, 426–442. [Google Scholar] [CrossRef]
  22. Skendi, A.; Zinoviadou, K.G.; Papageorgiou, M.; Rocha, J.M. Advances on the Valorisation and Functionalization of By-Products and Wastes from Cereal-Based Processing Industry. Foods 2020, 9, 1243. [Google Scholar] [CrossRef]
  23. Wieser, H.; Koehler, P.; Scherf, K.A. Chapter 5—Wheat-based raw materials. In Wheat—An Exceptional Crop; Wieser, H., Koehler, P., Scherf, K.A., Eds.; Woodhead Publishing: Sawston, UK, 2020; pp. 103–131. [Google Scholar]
  24. Elleuch, M.; Bedigian, D.; Roiseux, O.; Besbes, S.; Blecker, C.; Attia, H. Dietary fibre and fibre-rich by-products of food processing: Characterisation, technological functionality and commercial applications: A review. Food Chem. 2011, 124, 411–421. [Google Scholar] [CrossRef]
  25. Pathirannehelage, N.P.V.; Joye, I.J. Dietary Fibre from Whole Grains and Their Benefits on Metabolic Health. Nutrients 2020, 12, 3045. [Google Scholar] [CrossRef]
  26. Parchami, M.; Ferreira, J.A.; Taherzadeh, M.J. Starch and protein recovery from brewer’s spent grain using hydrothermal pretreatment and their conversion to edible filamentous fungi—A brewery biorefinery concept. Bioresour. Technol. 2021, 337, 125409. [Google Scholar] [CrossRef]
  27. Johansson, E.V.; Nilsson, A.C.; Östman, E.M.; Björck, I.M.E. Effects of indigestible carbohydrates in barley on glucose metabolism, appetite and voluntary food intake over 16 h in healthy adults. Nutr. J. 2013, 12, 46. [Google Scholar] [CrossRef] [Green Version]
  28. Zhu, F.; Du, B.; Xu, B. A critical review on production and industrial applications of beta-glucans. Food Hydrocoll. 2016, 52, 275–288. [Google Scholar] [CrossRef]
  29. Izydorczyk, M.S.; Dexter, J.E. Barley β-glucans and arabinoxylans: Molecular structure, physicochemical properties, and uses in food products—A Review. Food Res. Int. 2008, 41, 850–868. [Google Scholar] [CrossRef]
  30. Bastos, R.; Coelho, E.; Coimbra, M.A. 8-Arabinoxylans from cereal by-products: Insights into structural features, recovery, and applications. In Sustainable Recovery and Reutilization of Cereal Processing By-Products; Galanakis, C.M., Ed.; Woodhead Publishing: Sawston, UK, 2018; pp. 227–251. [Google Scholar]
  31. Pérez-Flores, J.G.; Contreras-López, E.; Castañeda-Ovando, A.; Pérez-Moreno, F.; Aguilar-Arteaga, K.; Álvarez-Romero, G.A.; Téllez-Jurado, A. Physicochemical characterization of an arabinoxylan-rich fraction from brewers’ spent grain and its application as a release matrix for caffeine. Food Res. Int. 2019, 116, 1020–1030. [Google Scholar] [CrossRef]
  32. Hughes, J.; Grafenauer, S. Oat and Barley in the Food Supply and Use of Beta Glucan Health Claims. Nutrients 2021, 13, 2556. [Google Scholar] [CrossRef]
  33. Onipe, O.O.; Jideani, A.I.O.; Beswa, D. Composition and functionality of wheat bran and its application in some cereal food products. Int. J. Food Sci. Technol. 2015, 50, 2509–2518. [Google Scholar] [CrossRef]
  34. Malunga, L.N.; Izydorczyk, M.; Beta, T. Effect of water-extractable arabinoxylans from wheat aleurone and bran on lipid peroxidation and factors influencing their antioxidant capacity. Bioact. Carbohydr. Diet. Fibre 2017, 10, 20–26. [Google Scholar] [CrossRef]
  35. Boll, E.V.; Ekström, L.M.; Courtin, C.M.; Delcour, J.A.; Nilsson, A.C.; Björck, I.M.; Östman, E.M. Effects of wheat bran extract rich in arabinoxylan oligosaccharides and resistant starch on overnight glucose tolerance and markers of gut fermentation in healthy young adults. Eur. J. Nutr. 2016, 55, 1661–1670. [Google Scholar] [CrossRef]
  36. Ahmad, A.; Anjum, F.M.; Zahoor, T.; Nawaz, H.; Dilshad, S.M. Beta glucan: A valuable functional ingredient in foods. Crit. Rev. Food Sci. Nutr. 2012, 52, 201–212. [Google Scholar] [CrossRef]
  37. Brennan, C.S.; Cleary, L.J. The potential use of cereal (1→3,1→4)-β-d-glucans as functional food ingredients. J. Cereal Sci. 2005, 42, 1–13. [Google Scholar] [CrossRef]
  38. Nguyen, N.K.; Deehan, E.C.; Zhang, Z.; Jin, M.; Baskota, N.; Perez-Muñoz, M.E.; Cole, J.; Tuncil, Y.E.; Seethaler, B.; Wang, T.; et al. Gut microbiota modulation with long-chain corn bran arabinoxylan in adults with overweight and obesity is linked to an individualized temporal increase in fecal propionate. Microbiome 2020, 8, 118. [Google Scholar] [CrossRef]
  39. Lam, K.-L.; Chi-Keung Cheung, P. Non-digestible long chain beta-glucans as novel prebiotics. Bioact. Carbohydr. Diet. Fibre 2013, 2, 45–64. [Google Scholar] [CrossRef]
  40. Treimo, J.; Westereng, B.; Horn, S.J.; Forssell, P.; Robertson, J.A.; Faulds, C.B.; Waldron, K.W.; Buchert, J.; Eijsink, V.G.H. Enzymatic Solubilization of Brewers’ Spent Grain by Combined Action of Carbohydrases and Peptidases. J. Agric. Food Chem. 2009, 57, 3316–3324. [Google Scholar] [CrossRef]
  41. Chetrariu, A.; Dabija, A. Brewer’s Spent Grains: Possibilities of Valorization, a Review. Appl. Sci. 2020, 10, 5619. [Google Scholar] [CrossRef]
  42. Bai, F.-W.; Yang, S.; Ho, N.W.Y. 3.05-Fuel Ethanol Production From Lignocellulosic Biomass. In Comprehensive Biotechnology, 3rd ed.; Moo-Young, M., Ed.; Pergamon: Oxford, UK, 2019; pp. 49–65. [Google Scholar]
  43. Henrion, M.; Francey, C.; Lê, K.A.; Lamothe, L. Cereal B-Glucans: The Impact of Processing and How It Affects Physiological Responses. Nutrients 2019, 11, 1729. [Google Scholar] [CrossRef] [Green Version]
  44. Steiner, J.; Procopio, S.; Becker, T. Brewer’s spent grain: Source of value-added polysaccharides for the food industry in reference to the health claims. Eur. Food Res. Technol. 2015, 241, 303–315. [Google Scholar] [CrossRef]
  45. Koh, E.M.; Lee, E.K.; Song, J.; Kim, S.J.; Song, C.H.; Seo, Y.; Chae, C.H.; Jung, K.J. Anticancer activity and mechanism of action of fermented wheat germ extract against ovarian cancer. J. Food Biochem. 2018, 42, e12688. [Google Scholar] [CrossRef]
  46. Stevenson, L.; Phillips, F.; O’Sullivan, K.; Walton, J. Wheat bran: Its composition and benefits to health, a European perspective. Int. J. Food Sci. Nutr. 2012, 63, 1001–1013. [Google Scholar] [CrossRef] [Green Version]
  47. Dapčević-Hadnađev, T.; Hadnađev, M.; Pojić, M. 2-The healthy components of cereal by-products and their functional properties. In Sustainable Recovery and Reutilization of Cereal Processing by-Products; Galanakis, C.M., Ed.; Woodhead Publishing: Sawston, UK, 2018; pp. 27–61. [Google Scholar]
  48. Kamal-Eldin, A.; Lærke, H.N.; Knudsen, K.E.; Lampi, A.M.; Piironen, V.; Adlercreutz, H.; Katina, K.; Poutanen, K.; Man, P. Physical, microscopic and chemical characterisation of industrial rye and wheat brans from the Nordic countries. Food Nutr. Res. 2009, 53, 19412350. [Google Scholar] [CrossRef] [Green Version]
  49. Knudsen, K.E.B.; Lærke, H.N. REVIEW: Rye Arabinoxylans: Molecular Structure, Physicochemical Properties and Physiological Effects in the Gastrointestinal Tract. Cereal Chem. 2010, 87, 353–362. [Google Scholar] [CrossRef]
  50. Prykhodko, O.; Sandberg, J.; Burleigh, S.; Björck, I.; Nilsson, A.; Fåk Hållenius, F. Impact of Rye Kernel-Based Evening Meal on Microbiota Composition of Young Healthy Lean Volunteers With an Emphasis on Their Hormonal and Appetite Regulations, and Blood Levels of Brain-Derived Neurotrophic Factor. Front. Nutr. 2018, 5, 45. [Google Scholar] [CrossRef]
  51. Johansson, L.; Tuomainen, P.; Anttila, H.; Rita, H.; Virkki, L. Effect of processing on the extractability of oat β-glucan. Food Chem. 2007, 105, 1439–1445. [Google Scholar] [CrossRef]
  52. Xu, D.; Feng, M.; Chu, Y.; Wang, S.; Shete, V.; Tuohy, K.M.; Liu, F.; Zhou, X.; Kamil, A.; Pan, D.; et al. The Prebiotic Effects of Oats on Blood Lipids, Gut Microbiota, and Short-Chain Fatty Acids in Mildly Hypercholesterolemic Subjects Compared With Rice: A Randomized, Controlled Trial. Front. Immunol. 2021, 12, 787797. [Google Scholar] [CrossRef]
  53. Ciudad-Mulero, M.; Fernández-Ruiz, V.; Matallana-González, M.C.; Morales, P. Chapter Two—Dietary fiber sources and human benefits: The case study of cereal and pseudocereals. In Advances in Food and Nutrition Research; Ferreira, I.C.F.R., Barros, L., Eds.; Academic Press: Cambridge, MA, USA, 2019; Volume 90, pp. 83–134. [Google Scholar]
  54. Ciecierska, A.; Drywień, M.E.; Hamulka, J.; Sadkowski, T. Nutraceutical functions of beta-glucans in human nutrition. Rocz. Panstw. Zakl. Hig. 2019, 70, 315–324. [Google Scholar] [CrossRef]
  55. Juhnevica-Radenkova, K.; Kviesis, J.; Moreno, D.A.; Seglina, D.; Vallejo, F.; Valdovska, A.; Radenkovs, V. Highly-Efficient Release of Ferulic Acid from Agro-Industrial By-Products via Enzymatic Hydrolysis with Cellulose-Degrading Enzymes: Part I–The Superiority of Hydrolytic Enzymes Versus Conventional Hydrolysis. Foods 2021, 10, 782. [Google Scholar] [CrossRef]
  56. Sandak, A.; Sandak, J.; Modzelewska, I. Manufacturing fit-for-purpose paper packaging containers with controlled biodegradation rate by optimizing addition of natural fillers. Cellulose 2019, 26, 2673–2688. [Google Scholar] [CrossRef] [Green Version]
  57. Gil-Chávez, J.; Gurikov, P.; Hu, X.; Meyer, R.; Reynolds, W.; Smirnova, I. Application of novel and technical lignins in food and pharmaceutical industries: Structure-function relationship and current challenges. Biomass Convers. Biorefinery 2021, 11, 2387–2403. [Google Scholar] [CrossRef]
  58. Schweiggert-Weisz, U.; Eisner, P.; Bader-Mittermaier, S.; Osen, R. Food proteins from plants and fungi. Curr. Opin. Food Sci. 2020, 32, 156–162. [Google Scholar] [CrossRef]
  59. Roth, M.; Jekle, M.; Becker, T. Opportunities for upcycling cereal byproducts with special focus on Distiller’s grains. Trends Food Sci. Technol. 2019, 91, 282–293. [Google Scholar] [CrossRef]
  60. Uraipong, C.; Zhao, J. Rice bran protein hydrolysates exhibit strong in vitro α-amylase, β-glucosidase and ACE-inhibition activities. J. Sci. Food Agric. 2016, 96, 1101–1110. [Google Scholar] [CrossRef]
  61. Wang, X.; Chen, H.; Fu, X.; Li, S.; Wei, J. A novel antioxidant and ACE inhibitory peptide from rice bran protein: Biochemical characterization and molecular docking study. LWT 2017, 75, 93–99. [Google Scholar] [CrossRef]
  62. Castro-Jácome, T.P.; Alcántara-Quintana, L.E.; Montalvo-González, E.; Chacón-López, A.; Kalixto-Sánchez, M.A.; del Pilar Rivera, M.; López-García, U.M.; Tovar-Pérez, E.G. Skin-protective properties of peptide extracts produced from white sorghum grain kafirins. Ind. Crops Prod. 2021, 167, 113551. [Google Scholar] [CrossRef]
  63. Lorenzo, J.M.; Munekata, P.E.; Gómez, B.; Barba, F.J.; Mora, L.; Pérez-Santaescolástica, C.; Toldrá, F. Bioactive peptides as natural antioxidants in food products—A review. Trends Food Sci. Technol. 2018, 79, 136–147. [Google Scholar] [CrossRef]
  64. Kaur, P.; Purewal, S.S.; Sandhu, K.S.; Kaur, M.; Salar, R.K. Millets: A cereal grain with potent antioxidants and health benefits. J. Food Meas. Charact. 2019, 13, 793–806. [Google Scholar] [CrossRef]
  65. Tapia-Hernández, J.A.; Del-Toro-Sánchez, C.L.; Cinco-Moroyoqui, F.J.; Juárez-Onofre, J.E.; Ruiz-Cruz, S.; Carvajal-Millan, E.; López-Ahumada, G.A.; Castro-Enriquez, D.D.; Barreras-Urbina, C.G.; Rodríguez-Felix, F. Prolamins from cereal by-products: Classification, extraction, characterization and its applications in micro- and nanofabrication. Trends Food Sci. Technol. 2019, 90, 111–132. [Google Scholar] [CrossRef]
  66. Zhou, C.; Hu, J.; Ma, H.; Yagoub, A.E.; Yu, X.; Owusu, J.; Ma, H.; Qin, X. Antioxidant peptides from corn gluten meal: Orthogonal design evaluation. Food Chem. 2015, 187, 270–278. [Google Scholar] [CrossRef]
  67. Connolly, A.; Piggott, C.O.; FitzGerald, R.J. Characterisation of protein-rich isolates and antioxidative phenolic extracts from pale and black brewers’ spent grain. Int. J. Food Sci. Technol. 2013, 48, 1670–1681. [Google Scholar] [CrossRef]
  68. Yu, D.; Sun, Y.; Wang, W.; O’Keefe, S.F.; Neilson, A.P.; Feng, H.; Wang, Z.; Huang, H. Recovery of protein hydrolysates from brewer’s spent grain using enzyme and ultrasonication. Int. J. Food Sci. Technol. 2020, 55, 357–368. [Google Scholar] [CrossRef]
  69. Qin, F.; Johansen, A.Z.; Mussatto, S.I. Evaluation of different pretreatment strategies for protein extraction from brewer’s spent grains. Ind. Crops Prod. 2018, 125, 443–453. [Google Scholar] [CrossRef]
  70. He, Y.; Kuhn, D.D.; Ogejo, J.A.; O’Keefe, S.F.; Fraguas, C.F.; Wiersema, B.D.; Jin, Q.; Yu, D.; Huang, H. Wet fractionation process to produce high protein and high fiber products from brewer’s spent grain. Food Bioprod. Process. 2019, 117, 266–274. [Google Scholar] [CrossRef]
  71. Li, W.; Yang, H.; Coldea, T.E.; Zhao, H. Modification of structural and functional characteristics of brewer’s spent grain protein by ultrasound assisted extraction. LWT 2021, 139, 110582. [Google Scholar] [CrossRef]
  72. Sganzerla, W.G.; Viganó, J.; Castro, L.E.N.; Maciel-Silva, F.W.; Rostagno, M.A.; Mussatto, S.I.; Forster-Carneiro, T. Recovery of sugars and amino acids from brewers’ spent grains using subcritical water hydrolysis in a single and two sequential semi-continuous flow-through reactors. Food Res. Int. 2022, 157, 111470. [Google Scholar] [CrossRef]
  73. Rodríguez-Restrepo, Y.A.; Ferreira-Santos, P.; Orrego, C.E.; Teixeira, J.A.; Rocha, C.M.R. Valorization of rice by-products: Protein-phenolic based fractions with bioactive potential. J. Cereal Sci. 2020, 95, 103039. [Google Scholar] [CrossRef]
  74. Bedin, S.; Zanella, K.; Bragagnolo, N.; Taranto, O.P. Implication of Microwaves on the Extraction Process of Rice Bran Protein. Braz. J. Chem. Eng. 2019, 36, 1653–1665. [Google Scholar] [CrossRef] [Green Version]
  75. Phongthai, S.; Lim, S.-T.; Rawdkuen, S. Optimization of microwave-assisted extraction of rice bran protein and its hydrolysates properties. J. Cereal Sci. 2016, 70, 146–154. [Google Scholar] [CrossRef]
  76. Prandi, B.; Faccini, A.; Lambertini, F.; Bencivenni, M.; Jorba, M.; Van Droogenbroek, B.; Bruggeman, G.; Schöber, J.; Petrusan, J.; Elst, K.; et al. Food wastes from agrifood industry as possible sources of proteins: A detailed molecular view on the composition of the nitrogen fraction, amino acid profile and racemisation degree of 39 food waste streams. Food Chem. 2019, 286, 567–575. [Google Scholar] [CrossRef]
  77. Alzuwaid, N.T.; Sissons, M.; Laddomada, B.; Fellows, C.M. Nutritional and functional properties of durum wheat bran protein concentrate. Cereal Chem. 2020, 97, 304–315. [Google Scholar] [CrossRef]
  78. Zhu, K.-X.; Zhou, H.-M.; Qian, H.-F. Proteins Extracted from Defatted Wheat Germ: Nutritional and Structural Properties. Cereal Chem. 2006, 83, 69–75. [Google Scholar] [CrossRef]
  79. Espinosa-Pardo, F.A.; Savoire, R.; Subra-Paternault, P.; Harscoat-Schiavo, C. Oil and protein recovery from corn germ: Extraction yield, composition and protein functionality. Food Bioprod. Process. 2020, 120, 131–142. [Google Scholar] [CrossRef]
  80. Guan, X.; Yao, H. Optimization of Viscozyme L-assisted extraction of oat bran protein using response surface methodology. Food Chem. 2008, 106, 345–351. [Google Scholar] [CrossRef]
  81. Kumar, K.; Yadav, A.N.; Kumar, V.; Vyas, P.; Dhaliwal, H.S. Food waste: A potential bioresource for extraction of nutraceuticals and bioactive compounds. Bioresour. Bioprocess. 2017, 4, 18. [Google Scholar] [CrossRef] [Green Version]
  82. Brinch-Pedersen, H.; Borg, S.; Tauris, B.; Holm, P.B. Molecular genetic approaches to increasing mineral availability and vitamin content of cereals. J. Cereal Sci. 2007, 46, 308–326. [Google Scholar] [CrossRef]
  83. Galanakis, C.M. Sustainable Applications for the Valorization of Cereal Processing By-Products. Foods 2022, 11, 241. [Google Scholar] [CrossRef] [PubMed]
  84. Jin, Z.; Lan, Y.; Ohm, J.-B.; Gillespie, J.; Schwarz, P.; Chen, B. Physicochemical composition, fermentable sugars, free amino acids, phenolics, and minerals in brewers’ spent grains obtained from craft brewing operations. J. Cereal Sci. 2022, 104, 103413. [Google Scholar] [CrossRef]
  85. Tuncel, N.B.; Yılmaz, N.; Kocabıyık, H.; Uygur, A. The effect of infrared stabilized rice bran substitution on B vitamins, minerals and phytic acid content of pan breads: Part II. J. Cereal Sci. 2014, 59, 162–166. [Google Scholar] [CrossRef]
  86. Lech, M.; Labus, K. The methods of brewers’ spent grain treatment towards the recovery of valuable ingredients contained therein and comprehensive management of its residues. Chem. Eng. Res. Des. 2022, 183, 494–511. [Google Scholar] [CrossRef]
  87. Luithui, Y.; Baghya Nisha, R.; Meera, M.S. Cereal by-products as an important functional ingredient: Effect of processing. J. Food Sci. Technol. 2019, 56, 1–11. [Google Scholar] [CrossRef]
  88. Feizollahi, E.; Mirmahdi, R.S.; Zoghi, A.; Zijlstra, R.T.; Roopesh, M.S.; Vasanthan, T. Review of the beneficial and anti-nutritional qualities of phytic acid, and procedures for removing it from food products. Food Res. Int. 2021, 143, 110284. [Google Scholar] [CrossRef]
  89. Górnaś, P.; Rudzińska, M.; Raczyk, M.; Soliven, A. Lipophilic bioactive compounds in the oils recovered from cereal by-products. J. Sci. Food Agric. 2016, 96, 3256–3265. [Google Scholar] [CrossRef]
  90. Papageorgiou, M.; Skendi, A. 1-Introduction to cereal processing and by-products. In Sustainable Recovery and Reutilization of Cereal Processing by-Products; Galanakis, C.M., Ed.; Woodhead Publishing: Sawston, UK, 2018; pp. 1–25. [Google Scholar]
  91. Saad, N.; Ismail, N.; Mastuki, S.N.; Leong, S.W.; Chia, S.L.; Abdullah, C.A.C. Chapter 16—Rice bran oil main bioactive compounds and biological activities. In Multiple Biological Activities of Unconventional Seed Oils; Mariod, A.A., Ed.; Academic Press: Cambridge, MA, USA, 2022; pp. 195–213. [Google Scholar]
  92. Xu, D.; Hao, J.; Wang, Z.; Liang, D.; Wang, J.; Ma, Y.; Zhang, M. Physicochemical properties, fatty acid compositions, bioactive compounds, antioxidant activity and thermal behavior of rice bran oil obtained with aqueous enzymatic extraction. LWT 2021, 149, 111817. [Google Scholar] [CrossRef]
  93. Meriles, S.P.; Penci, M.C.; Curet, S.; Boillereaux, L.; Ribotta, P.D. Effect of microwave and hot air treatment on enzyme activity, oil fraction quality and antioxidant activity of wheat germ. Food Chem. 2022, 386, 132760. [Google Scholar] [CrossRef] [PubMed]
  94. Wang, J.; Tang, J.; Ruan, S.; Lv, R.; Zhou, J.; Tian, J.; Cheng, H.; Xu, E.; Liu, D. A comprehensive review of cereal germ and its lipids: Chemical composition, multi-objective process and functional application. Food Chem. 2021, 362, 130066. [Google Scholar] [CrossRef] [PubMed]
  95. Patel, A.; Mikes, F.; Bühler, S.; Matsakas, L. Valorization of Brewers’ Spent Grain for the Production of Lipids by Oleaginous Yeast. Molecules 2018, 23, 3052. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  96. del Río, J.C.; Prinsen, P.; Gutiérrez, A. Chemical composition of lipids in brewer’s spent grain: A promising source of valuable phytochemicals. J. Cereal Sci. 2013, 58, 248–254. [Google Scholar] [CrossRef] [Green Version]
  97. Borsini, A.; Nicolaou, A.; Camacho-Muñoz, D.; Kendall, A.C.; Di Benedetto, M.G.; Giacobbe, J.; Su, K.P.; Pariante, C.M. Omega-3 polyunsaturated fatty acids protect against inflammation through production of LOX and CYP450 lipid mediators: Relevance for major depression and for human hippocampal neurogenesis. Mol. Psychiatry 2021, 26, 6773–6788. [Google Scholar] [CrossRef]
  98. Li, D.; Zhang, J.; Faiza, M.; Shi, L.; Wang, W.; Liu, N.; Wang, Y. The enhancement of rice bran oil quality through a novel moderate biorefining process. LWT 2021, 151, 112118. [Google Scholar] [CrossRef]
  99. Liu, J.; Jin, S.; Song, H.; Huang, K.; Li, S.; Guan, X.; Wang, Y. Effect of extrusion pretreatment on extraction, quality and antioxidant capacity of oat (Avena Sativa L.) bran oil. J. Cereal Sci. 2020, 95, 102972. [Google Scholar] [CrossRef]
  100. Zhao, M.; Lan, Y.; Cui, L.; Monono, E.; Rao, J.; Chen, B. Formation, characterization, and potential food application of rice bran wax oleogels: Expeller-pressed corn germ oil versus refined corn oil. Food Chem. 2020, 309, 125704. [Google Scholar] [CrossRef]
  101. Povilaitis, D.; Venskutonis, P.R. Optimization of supercritical carbon dioxide extraction of rye bran using response surface methodology and evaluation of extract properties. J. Supercrit. Fluids 2015, 100, 194–200. [Google Scholar] [CrossRef]
  102. Klempová, T.; Slaný, O.; Šišmiš, M.; Marcinčák, S.; Čertík, M. Dual production of polyunsaturated fatty acids and beta-carotene with Mucor wosnessenskii by the process of solid-state fermentation using agro-industrial waste. J. Biotechnol. 2020, 311, 1–11. [Google Scholar] [CrossRef]
  103. Franco, R.; Navarro, G.; Martínez-Pinilla, E. Antioxidants versus Food Antioxidant Additives and Food Preservatives. Antioxidants 2019, 8, 542. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  104. Lourenço, S.C.; Moldão-Martins, M.; Alves, V.D. Antioxidants of Natural Plant Origins: From Sources to Food Industry Applications. Molecules 2019, 24, 4132. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  105. de Lima Cherubim, D.J.; Buzanello Martins, C.V.; Oliveira Fariña, L.; da Silva de Lucca, R.A. Polyphenols as natural antioxidants in cosmetics applications. J. Cosmet. Dermatol. 2020, 19, 33–37. [Google Scholar] [CrossRef] [PubMed]
  106. Costa, R.; Santos, L. Delivery systems for cosmetics-From manufacturing to the skin of natural antioxidants. Powder Technol. 2017, 322, 402–416. [Google Scholar] [CrossRef]
  107. Janciauskiene, S. The beneficial effects of antioxidants in health and diseases. Chronic Obstr. Pulm. Dis. J. COPD Found. 2020, 7, 182. [Google Scholar] [CrossRef]
  108. Yang, C.S.; Ho, C.-T.; Zhang, J.; Wan, X.; Zhang, K.; Lim, J. Antioxidants: Differing meanings in food science and health science. J. Agric. Food Chem. 2018, 66, 3063–3068. [Google Scholar] [CrossRef]
  109. Socaci, S.A.; Rugină, D.O.; Diaconeasa, Z.M.; Pop, O.L.; Fărcaș, A.C.; Păucean, A.; Tofană, M.; Pintea, A. Antioxidant compounds recovered from food wastes. In Functional Food-Improve Health through Adequate Food; IntechOpen: London, UK, 2017. [Google Scholar]
  110. Dursun, D.; Dalgıç, A.C. Optimization of astaxanthin pigment bioprocessing by four different yeast species using wheat wastes. Biocatal. Agric. Biotechnol. 2016, 7, 1–6. [Google Scholar] [CrossRef]
  111. Machado, E.; Matumoto Pintro, P.T.; Ítavo, L.C.V.; Agustinho, B.C.; Daniel, J.L.P.; Santos, N.W.; Bragatto, J.M.; Ribeiro, M.G.; Zeoula, L.M. Reduction in lignin content and increase in the antioxidant capacity of corn and sugarcane silages treated with an enzymatic complex produced by white rot fungus. PLoS ONE 2020, 15, e0229141. [Google Scholar] [CrossRef] [Green Version]
  112. Spinelli, S.; Conte, A.; Lecce, L.; Padalino, L.; Del Nobile, M.A. Supercritical carbon dioxide extraction of brewer’s spent grain. J. Supercrit. Fluids 2016, 107, 69–74. [Google Scholar] [CrossRef]
  113. Petrón, M.; Andrés, A.; Esteban, G.; Timón, M. Study of antioxidant activity and phenolic compounds of extracts obtained from different craft beer by-products. J. Cereal Sci. 2021, 98, 103162. [Google Scholar] [CrossRef]
  114. Walters, M.E.; Willmore, W.G.; Tsopmo, A. Antioxidant, physicochemical, and cellular secretion of glucagon-like peptide-1 properties of oat bran protein hydrolysates. Antioxidants 2020, 9, 557. [Google Scholar] [CrossRef] [PubMed]
  115. Guerrini, A.; Burlini, I.; Lorenzo, B.H.; Grandini, A.; Vertuani, S.; Tacchini, M.; Sacchetti, G. Antioxidant and antimicrobial extracts obtained from agricultural by-products: Strategies for a sustainable recovery and future perspectives. Food Bioprod. Process. 2020, 124, 397–407. [Google Scholar] [CrossRef]
  116. Zhang, H.J.; Wang, J.; Zhang, B.H.; Zhang, H. Antioxidant activities of the fractionated protein hydrolysates from heat stable defatted rice bran. Int. J. Food Sci. Technol. 2014, 49, 1330–1336. [Google Scholar] [CrossRef]
  117. Cheetangdee, N.; Benjakul, S. Antioxidant activities of rice bran protein hydrolysates in bulk oil and oil-in-water emulsion. J. Sci. Food Agric. 2015, 95, 1461–1468. [Google Scholar] [CrossRef] [PubMed]
  118. Huang, H.; Wang, Z.; Aalim, H.; Limwachiranon, J.; Li, L.; Duan, Z.; Ren, G.; Luo, Z. Green recovery of phenolic compounds from rice byproduct (rice bran) using glycerol based on viscosity, conductivity and density. Int. J. Food Sci. Technol. 2019, 54, 1363–1371. [Google Scholar] [CrossRef]
  119. Görgüç, A.; Özer, P.; Yılmaz, F.M. Microwave-assisted enzymatic extraction of plant protein with antioxidant compounds from the food waste sesame bran: Comparative optimization study and identification of metabolomics using LC/Q-TOF/MS. J. Food Process. Preserv. 2020, 44, e14304. [Google Scholar] [CrossRef]
  120. Kawaguchi, T.; Ueno, T.; Nogata, Y.; Hayakawa, M.; Koga, H.; Torimura, T. Wheat-bran autolytic peptides containing a branched-chain amino acid attenuate non-alcoholic steatohepatitis via the suppression of oxidative stress and the upregulation of AMPK/ACC in high-fat diet-fed mice. Int. J. Mol. Med. 2017, 39, 407–414. [Google Scholar] [CrossRef] [Green Version]
  121. Mikucka, W.; Zielinska, M.; Bulkowska, K.; Witonska, I. Recovery of polyphenols from distillery stillage by microwave-assisted, ultrasound-assisted and conventional solid–liquid extraction. Sci. Rep. 2022, 12, 1–13. [Google Scholar]
  122. Călinoiu, L.F.; Vodnar, D.C. Thermal processing for the release of phenolic compounds from wheat and oat bran. Biomolecules 2019, 10, 21. [Google Scholar] [CrossRef] [Green Version]
  123. Zaky, A.A.; Abd El-Aty, A.; Ma, A.; Jia, Y. An overview on antioxidant peptides from rice bran proteins: Extraction, identification, and applications. Crit. Rev. Food Sci. Nutr. 2022, 62, 1350–1362. [Google Scholar] [CrossRef]
  124. Stefanello, F.S.; Dos Santos, C.O.; Bochi, V.C.; Fruet, A.P.B.; Soquetta, M.B.; Dörr, A.C.; Nörnberg, J.L. Analysis of polyphenols in brewer’s spent grain and its comparison with corn silage and cereal brans commonly used for animal nutrition. Food Chem. 2018, 239, 385–401. [Google Scholar] [CrossRef] [PubMed]
  125. Kottaras, P.; Koulianos, M.; Makris, D.P. Low-Transition temperature mixtures (LTTMs) made of bioorganic molecules: Enhanced extraction of antioxidant phenolics from industrial cereal solid wastes. Recycling 2017, 2, 3. [Google Scholar] [CrossRef] [Green Version]
  126. Fu, L.; Li, F.; Bruckbauer, A.; Cao, Q.; Cui, X.; Wu, R.; Shi, H.; Xue, B.; Zemel, M.B. Interaction between leucine and phosphodiesterase 5 inhibition in modulating insulin sensitivity and lipid metabolism. Diabetes Metab. Syndr. Obes. Targets Ther. 2015, 8, 227. [Google Scholar]
  127. Elhassan, F.; Suad, A.; Dahawi, F. Antimicrobial activities of six types of wheat bran. IOSR J. Appl. Chem. 2017, 10, 61–69. [Google Scholar] [CrossRef]
  128. Moreirinha, C.; Vilela, C.; Silva, N.H.C.S.; Pinto, R.J.B.; Almeida, A.; Rocha, M.A.M.; Coelho, E.; Coimbra, M.A.; Silvestre, A.J.D.; Freire, C.S.R. Antioxidant and antimicrobial films based on brewers spent grain arabinoxylans, nanocellulose and feruloylated compounds for active packaging. Food Hydrocoll. 2020, 108, 105836. [Google Scholar] [CrossRef]
  129. Mitrea, L.; Nemeş, S.A.; Szabo, K.; Teleky, B.E.; Vodnar, D.C. Guts Imbalance Imbalances the Brain: A Review of Gut Microbiota Association With Neurological and Psychiatric Disorders. Front. Med. Lausanne 2022, 9, 813204. [Google Scholar] [CrossRef]
  130. McCarthy, A.L.; O’Callaghan, Y.C.; Connolly, A.; Piggott, C.O.; FitzGerald, R.J.; O’Brien, N.M. Phenolic-enriched fractions from brewers’ spent grain possess cellular antioxidant and immunomodulatory effects in cell culture model systems. J. Sci. Food Agric. 2014, 94, 1373–1379. [Google Scholar] [CrossRef]
  131. McCarthy, A.L.; O’Callaghan, Y.C.; Connolly, A.; Piggott, C.O.; FitzGerald, R.J.; O’Brien, N.M. Brewers’ spent grain (BSG) protein hydrolysates decrease hydrogen peroxide (H2O2)-induced oxidative stress and concanavalin-A (con-A) stimulated IFN-γ production in cell culture. Food Funct. 2013, 4, 1709–1716. [Google Scholar] [CrossRef]
Figure 1. Reintegration of cereal by-products in human consumption.
Figure 1. Reintegration of cereal by-products in human consumption.
Nutrients 14 03470 g001
Table 1. The main carbohydrates composition of different grain by-products and their potential application.
Table 1. The main carbohydrates composition of different grain by-products and their potential application.
CompoundsBy-ProductConcentrationIndustrial ApplicationsHealth BenefitsReferences
Residual undigested starchBSG1.3–10%Production of fungal biomass and ethanol;
Development of prebiotic ingredients for the meat industry
Positive effects on metabolism regulate the fermentative processes in the colon and increase the levels of glucagon-like peptide-1, known for its anti-diabetic and anti-obesogenic features[22,26,27,28]
Beta-glucansOat bran5.5% dry matterUsing supercritical carbon dioxide to remove the oat bran lipids can increase by more than 40% the beta-glucan level;
Incorporated high molecular weight oat beta-glucan into milk to obtain calorie-reduced and cholesterol-lowering dairy products;
Increase of beverage satiety capacity;
Ingredient for wheat flour substitutes;
Food hydrocolloids;
Wound dressing products;
Curing partial-thickness burns;
A bone-substituting material;
Novel prebiotics;
Film-forming moisturizer;
Skin and dermatological compositions;
Cosmetic product;
Animal and fish feed additives
Antioxidant and antiproliferative activities, regulate the glycemic index and blood sugar and reduce LDL cholesterol.
Immune-modulating effects, prophylactic roles against colorectal cancer, prolong satiety and have prebiotic effects, facilitating the elimination of fecal matter and avoiding constipation problems
Anti-inflammatory, skin-care effects
[22,28,29,47]
BSG0.36% dry matter
ArabinoxylansDifferent cereals bran10.9–26.0% of the bran dry matterFood-thickening and stabilizing agents
and films for the food industry (packaging materials);
Controlled release of bioactive compounds.
Prebiotic effect, reduce the risk of metabolic disorders such as obesity,
have the ability to regulate the postprandial glycemic response and stabilize cholesterol levels
Minimizes the risk of developing diabetes and chronic heart disease Anticarcinogenic properties
[30,31,33,47]
CelluloseRye bran5.5–6.5%Feed supplement
Paper packaging containers
It facilitates the shortening of the intestinal transit time and also the elimination of possible carcinogens, which contributes to reducing the risk of developing colon cancer.[22,47,53,55,56]
Wheat bran9.3–12.1%
BSG15.1–25%
LigninBSG7–28%Food industry (dispersing, binding, and emulsifying agent), food supplement, animal feed and medicine, construction industry, cosmetic products, crop protection (lignin-based pesticides), printing inkAnticarcinogenic, antimicrobial, and antioxidant properties, increase fecal bulk and stimulates intestinal transit, can undergo fermentation when exposed to colon microbiota, anti-hyperlipidemia and anti-obesogenic agent, protective activity against oxidative stress and inhibition of LDL oxidation[22,33,47,53,57]
Wheat bran3.3–4.9%
Corn bran10 g/kg
BSG—brewers’ spent grain.
Table 2. Bioactive proteins and amino acids recovered from cereal by-products and waste.
Table 2. Bioactive proteins and amino acids recovered from cereal by-products and waste.
Cereal WasteProtein/Amino Acids QuantityExtraction Methods/TreatmentsExtraction Efficiency/YieldProperties/Applications/Other ObservationsReferences
Brewers’ Spent Grain
(BSG)
Protein: 23.10 g/100 g dw for pale BSG
Protein: 26.93 g/100 g dw for black BSG
Sequential aqueous and alkaline (110 mM NaOH) extraction, followed by isoelectric
precipitation (pH 3.8)
Pale BSG: 59% protein extraction yield
Black BSG: 15% protein extraction yield
Protein-enriched isolates can be used as bioactive ingredients for incorporation into conventional and functional foods.[67]
Protein: 23.4 g/100 g BSG dwEnzymatic (Alcalase 2.4 L) and ultrasound-assisted enzymatic extraction (amplitude 40%, treatment time 10 min, pulse 5 s:3 s off)61.6% recovery for enzymatic treatments and 69.8% recovery for ultrasound enzymatic extractionUltrasound pretreatment increases the efficiency of protein separation, reduces enzyme loading, and decreases enzyme incubation time.[68]
Protein: 22.63 g/100 g defatted BSGAcid pretreatment (one-step dilute acid pretreatment with the acid solution (11,400 mg H2SO4/g BSG) autoclaved at 121 °C for 1 h)
Hydrothermal pretreatment (a. 60 °C/24 h, shaker incubator—250 rpm)/(b. 25 °C, 1.5 h)
Protein extraction efficiency 90%
Protein extraction efficiency:
64–66% (a) and 43% (b)
Even though the acid treatment had a higher efficiency, a significant amount of carbohydrates and lignin was also solubilized together with protein; instead, the hydrothermal pretreatment had a better selectivity and is more
environmentally friendly.
[69]
Protein: 22.9 g/100 g defatted BSGSodium hydroxide treatment
5% (w/w)
Alcalase treatment (20 μL/g dry BSG)
Sodium bisulfite treatment (5% w/w)
Protein separation
efficiency 81.8%
Protein separation
efficiency 83.7%
Protein separation efficiency
68%
Enzymatic treatment proved to be the most effective and the resulting protein concentrate
had also the highest lysine content (4.1%, w/w).
[70]
Protein: 24.70 g/100 g dwSodium hydroxide (110 mM) and ultrasound treatment (power 250 W, duty cycle 60%, 20 min/25 °C)Extraction yield of 86.16% and purity at 57.84%Plant-based protein source to the food industry.
Improved fat absorption capacity, emulsifying, and foaming properties.
[71]
Amino acids: 43.62 mg/g−1 proteinsSubcritical water hydrolysis in a single reactor (120 min at 15 MPa, 5 mL water min, 80–180 °C, solid: fluid of 20 g−1 BSG)The main amino acids of hydrolysate: tryptophan 215.55 µg mL−1, aspartic acid 123.35 µg mL−1, valine 64.35 µg mL−1, lysine 16.55 µg mL−1, and glycine 16.1 µg mL−1Applicability in the field of food and supplements production[72]
Rice bran defatted (RBD)Soluble proteins: 8.23 g/100 RBDAlkaline extraction
of proteins and fractionation by the Osborne method
55.8% of the total soluble proteins, of which 6.1%albumin, 4.5% globulin, and 43.5% glutelin.Applicability in the field of food and supplements and cosmetics production.[73]
Protein: 15.67 g/100 g RBDAlkaline extraction
(60 min, pH 11, 55 °C)
Microwave-assisted extraction (120 s; pH 11, 55 °C)
Protein content of concentrated product 75.32% and extraction yield 12.85%
Protein content of concentrated product 79.98% and extraction yield 15.68%
Comparing the two methods, the microwave-assisted one proved to be more efficient and environmentally friendly. Also, the microwaves did not affect the extracted rice bran proteins.[74]
Protein: 14.13% of concentrate productMicrowave-assisted extraction (1000 W of MW power, extraction time 90 s, solid to liquid ratio of 0.89 g rice bran/10 mL of distilled water) and response surface methodologyProtein content of concentrated product 71.27% and recovery yield 22.07%Food industry—strong antioxidant activity.
MAE is considered an environmentally friendly technique.
[75]
Malted barley germs
(MBG)
Protein: 29.1% on a dry matter basisAmino acid profile by LC/fluorescenceTotal amino acid 214 mg/g of which 35–40% are essential (leucine
15.7 mg/g, valine 13.5 mg/g, lysine 11.7 mg/g, and arginine 12.5 mg/g dw
Valuable source of good quality nitrogen fraction.
Applicability in the field of food and supplements production.
[76]
Brewing cakeProtein: 30.4% on a dry matter basisAmino acid profile by LC/fluorescenceTotal amino acid content
238 mg/g of witch 35–40% are essential amino acids (leucine 18.0 mg/g), phenylalanine
14.6 mg/g, valine 13.3 mg/g, cysteine 11.3 mg/g, arginine 12.1 mg/g dw
Valuable source of good quality nitrogen fraction.
Applicability in the field of food and supplements production.
[76]
Wheat bran (WB)Protein: 17.2 g/100 g WB dw
Total amino acids (AA): 12.5 g/100 g WB proteinTotal essential amino acids (EAA):
of 4.28 g/100 g WB protein
Alkaline extraction (pH 9.5, 2 h, followed by isoelectric precipitation, pH 4.2)Wheat bran concentrate (WBPC) protein content: 61%
Protein recovery yield: 20.5–24.8%
Total AA of WBPC 60.11 g/100 g), total EAA 22.79 g/100 g
WBPC showed excellent functional properties in terms of high solubility, good water, and fat absorption capacity.
Balanced amino acid composition, high in essential amino acids, with good levels of lysine and threonine, and phenolic acids.
[77]
Defatted Wheat Germ
(DWG)
Protein: 34.9% dw (albumin 34.5%
globulin 15.6%, glutelin 10.6%, and prolamine
4.6%)
Alcaline extraction
(pH 9.5 with 1 M NaOH, stirring 30 min, the supernatant was adjusted to pH 4.0 with 1.0 M HCl to precipitate the proteins, washed and adjusted to pH 7.0 using 0.1 M NaOH, then freeze-dried)
Isolate protein content 88.5%, recovery yield in the range of 24.0–37.0%Significant level of essential amino acids.
DWG can be considered a good vegetable protein supplement for cereal-based diets.
[78]
Defatted corn germ (DCG)Protein: 12.48% fresh weight basisAlkaline extraction of corn germ partially defatted by supercritical fluid extractionProtein content of DCG concentrate 48.5% dry base reported
Yield of protein extraction 21.3%
Good foaming capacity and stability[79]
Defatted oat bran (DOB)Protein: 17.6%Enzyme-assisted extraction (Viscozyme L, pH 4.6, incubation time 2.8 h, and temperature 44 °C)Extraction yield 56.2%Applicability in the field of food and supplements production.[80]
dw—dry weight basis; fw—fresh weight basis.
Table 4. Antioxidant compounds recovered from cereals wastes and by-products.
Table 4. Antioxidant compounds recovered from cereals wastes and by-products.
Cereal WasteAntioxidant CompoundsExtraction Methods/BiotechnologyExtraction/
Production Yield
Antioxidant ActivityApplicationReferences
Corn silagePolyphenolsEnzymatic treatment412.83 mg GAE/100 g2961.6 μM (ABTS)-[111]
Brewers’ spent grainPhenolic compoundsSupercritical carbon dioxide3 g mass of extract2% DPPH [112]
PolyphenolsAcidifies solution (pH 2,5–3)1.14 mg GAE/g8–13%-[113]
Oat branProtein hydrolysatesHydrolyzed with Flavourzyme (1), Papain (2), or Alcalase (3)89–93%627.17 (1); 682.90 (2); 652.67 (3) µM TE/g (ORAC)-[114]
Rice branFree phenols
Bound phenols
Ultrasound-assisted extraction (65% ethanolic solution)
Ultrasound-assisted alkaline hydrolysis
17–20%275.1 (DPPH) IC50 (μg/mL)
38.01 (DPPH) IC50 (μg/mL)
Cosmetic formulation[115]
Protein hydrolysatesHydrolysate by Alcalase 2.4 L and Protease 500 G79.12%75–90% (DPPH)-[116]
Protein hydrolysatesProtein enzyme-assisted extraction/hydrolysis-2.8 μmol TE/g (DPPH)Food additive[117]
PolyphenolsGlycerol extraction708.58 ± 12.36 mg GAE/100 g dw700.35 mg
GAE/100 g
-[118]
Sesame branPhenolsMicrowave-assisted enzymatic extraction-1.94 µmol TE/gFunctional food ingredient[119]
Wheat branFree phenols
Bound phenols
Ultrasound-assisted extraction (65% ethanolic solution)
Ultrasound-assisted alkaline hydrolysis
17–20%1194.8 (DPPH) IC50 (μg/mL)
3.61 (DPPH) IC50 (μg/mL)
Cosmetic formulation[115]
PeptidesHPLC purification-3000–3300 μmol/L biological antioxidant potential (free radical analyzer system)Antidiabetic compound[120]
Wheat and rye waste (distillery stillage)PolyphenolsConventional solid-liquid extraction (1)
Ultrasound-assisted extraction (2)
Microwave-assisted extraction (3)
52–99%10.84 (1); 16.67 (2); 26.73 (3) μmol TE/g (ABTS)
10.84 (1); 2.95 (2); 5.57 (3) μmol TE/g (DPPH)
36.73 (1); 5.57 (2); 3.71 (3) μmol FeSO4/g (FRAP)
-[121]
Wheat wasteAstaxanthinSolid state fermentation17–109%90–95% of the antioxidant (DPPH) activity of astaxanthin from plant-[110]
Wheat and Oat BranPhenolic compoundsUltrasound-assisted extraction25–50 mg GAE/100 g40–52% (DPPH)-[122]
“DPPH”—2,2-diphenyl-1-picrylhydrazyl; “IC50”—half maximal inhibitory concentration; “-“ not mentioned; “TE”/“GAE”—trolox/gallic acid equivalent; “ORAC”—oxygen radical absorbance capacity; “ABTS”—2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid); “FRAP”—ferric reducing antioxidant power assay.
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Fărcaș, A.C.; Socaci, S.A.; Nemeș, S.A.; Pop, O.L.; Coldea, T.E.; Fogarasi, M.; Biriș-Dorhoi, E.S. An Update Regarding the Bioactive Compound of Cereal By-Products: Health Benefits and Potential Applications. Nutrients 2022, 14, 3470. https://doi.org/10.3390/nu14173470

AMA Style

Fărcaș AC, Socaci SA, Nemeș SA, Pop OL, Coldea TE, Fogarasi M, Biriș-Dorhoi ES. An Update Regarding the Bioactive Compound of Cereal By-Products: Health Benefits and Potential Applications. Nutrients. 2022; 14(17):3470. https://doi.org/10.3390/nu14173470

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Fărcaș, Anca Corina, Sonia Ancuța Socaci, Silvia Amalia Nemeș, Oana Lelia Pop, Teodora Emilia Coldea, Melinda Fogarasi, and Elena Suzana Biriș-Dorhoi. 2022. "An Update Regarding the Bioactive Compound of Cereal By-Products: Health Benefits and Potential Applications" Nutrients 14, no. 17: 3470. https://doi.org/10.3390/nu14173470

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