Search Results (35)

The growing demand for sustainable biorefinery approaches calls for efficient, environmentally benign strategies to valorize agricultural residues and ensure their complete utilization. This study explores the combination of deep eutectic solvents (DESs) and microwave heating technology as a greener process for the selective fractionation of agri-food waste residues in a zero-waste perspective. Within this framework, five representative biomasses were thoroughly investigated, namely brewer’s spent grain, raw and parboiled rice husks, rapeseed cakes, and hemp hurds. DES formulation was selected for its ability to solubilize and separate lignocellulosic components, enabling the recovery of a polysaccharide-rich fraction, lignin, and bioactive compounds. DES extraction was performed using both microwave heating and conventional batch heating, enabling a direct comparison of the two methods, the optimization of a more sustainable fractionation process, and the maximization of yields while preserving the functional integrity of the recovered fractions. A comprehensive characterization of the separated fractions was carried out, revealing that the two fractionation methods do not yield significant differences in the composition of the primary components. Moreover, a ¹³C CP-MAS NMR analysis of the recovered lignins demonstrates how this analytical technique is a real fingerprint for the biomass source. The results demonstrate the great potential of microwave DES-mediated fractionation as a mild, tunable, and sustainable alternative to conventional methods, aligning with green chemistry principles and opening new approaches for the full valorization of waste byproducts Full article

Brewer’s spent grain (BSG) is the main solid byproduct of the brewing industry, generated in large quantities worldwide. Its high organic content and availability make it an attractive substrate for biotechnological valorization and recycling within a circular economy framework, contributing to the recovery and reuse of agro-industrial residues. This study investigates the potential of Talaromyces stollii I05.06 to simultaneously produce laccase and release phenolic compounds through submerged fermentation (SmF) using BSG as the sole carbon source. Initial SmF trials confirmed the fungus’s capacity to metabolize BSG. Subsequent fermentations with phosphate buffer supplementation (100 mM) significantly enhanced laccase activity (1535 ± 151.6 U·L⁻¹ on day 5) and phenolic content (6.28 ± 0.07 mg GAE per 100 g on day 1 with 50 mM buffer). However, the addition of typical laccase inducers (Cu²⁺ and Mn²⁺) led to inhibitory effects. The results highlight T. stollii I05.06 as a promising microorganism for the integrated valorization of BSG, contributing to sustainable agro-industrial waste management and the development of value-added bioproducts. Full article

During the preparation of beer wort, significant amounts of waste raw materials, such as brewers’ spent grain (BSG), are generated. In line with the zero-waste approach, a processing technology for BSG was developed to valorize this by-product. The developed method involves obtaining a BSG extract (plant-based milk), followed by filtration to remove insoluble residues and subsequent fermentation to produce vegan BSG-based yogurt-like products, with and without the addition of sucrose, as well as pectin, guar gum, and konjac gum as stabilizers. The samples were analyzed for pH, moisture and protein content, water activity (Aw), color, viscosity, and syneresis, and were also subjected to an organoleptic evaluation. Fermentation with starter cultures yielded BSG-based yogurt-like products with an optimal pH (~4.0), which, combined with Aw values below 0.95, ensures microbiological safety by inhibiting the growth of pathogenic and spoilage microorganisms. Due to phase separation, the use of stabilizers was necessary to achieve a yogurt-like texture. Their application also contributed to a reduction in syneresis—sometimes even preventing its occurrence—and led to an increase in viscosity, which ranged from 0.162 to 0.463 Pa·s, depending on the stabilizer used. The moisture content of fermented BSG extracts ranged from 88.2% to 91.7%. All samples showed similar protein content, approximately 50% on a dry matter basis. Furthermore, organoleptic assessment (5-point scale) revealed that sensory characteristics varied depending on the stabilizer and sugar used. The yogurt-like variant formulated with 0.5% pectin and 1% sucrose received the highest acceptance score (4.0), indicating good sensory quality. Full article

The objective of this study was to evaluate how high-energy milling affects the structural, thermal, and morphological properties of brewer’s spent grain fibers over time. The researchers determined the chemical composition of the samples using TAPPI techniques, particle size analysis, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and X-ray diffraction (XRD). The samples displayed distinct morphologies and particle sizes depending on the treatment duration. The sample treated for 120 min (T120) showed the smallest particle size (19.4 µm). FTIR spectra revealed that the mechanical treatment strongly disrupted the structure of hemicellulose. The thermal stability of the samples decreased because of the applied treatment. Mechanical milling also fully eliminated the crystalline structure of cellulose in the samples. These findings indicate that high-energy milling holds strong potential as a pre-treatment method for the valorization of lignocellulosic residues. Full article

Large quantities of brewer’s spent grains are not fully utilized even as cattle feed. These feedstocks can be used to produce highly functional biomaterials, carbonaceous materials, and additives. In this investigation, four major fractions were isolated and characterized: Hemicellulose A, Hemicellulose B, cellulosic-rich fraction (CRF), and oligosaccharides. Overall, 21.4% Hemicellulose A, 18.5% Hemicellulose B, 17.4% cellulosic rich fraction, and 5.5% pure oligosaccharides were obtained from the hexane-extracted brewery’s spent grains. Detailed physio-chemical analyses of each fraction showed that these fractions can be used to produce useful products such as emulsifiers, carbonaceous materials, modified cellulosic fibers, additives, as well as N-doped chars. Component analyses revealed that, Hemi. A contains high fixed carbon (20 wt.%), followed by hexane extracted material (17.1 wt.%), CRF (14.6 wt.%), and Hemi. B (14.5%). Standard proximate analyses showed that Hemi. A has the highest protein (66 wt.%), which can be utilized as a renewable solid-state N-precursor as dopants during the thermochemical conversion process. The sugar composition revealed that BSG has a typical arabinoxylan structure with a high percentage of arabinose and xylose. It also contains a high percentage of glucose, which may come from the residual β-glucan present in the BSG. FTIR analyses revealed changes in the structure of each fraction. Hence, BSG and extracted fractions exhibit significant potential for waste valorization, contributing significantly to the full utilization of products from the brewing industry. Full article

Of the three types of waste generated in beer processing, brewer’s spent grain (BSG) is the most abundant and has a high potential for valorization. In this work, defatted BSG (DB) was subjected to an extraction process with subcritical water at different temperatures to obtain extracts rich in phenols and the cellulosic fractions, which were also purified by using hydrogen peroxide (H₂O₂). The results showed that the dry extracts obtained at 170 °C were richer in phenolics (24 mg Gallic Acid Equivalent (GAE) g⁻¹ DB), but with lower antioxidant capacity (71 mg DB·mg⁻¹ 2,2-diphenyl-1-pikryl-hydrazyl). This extract also showed the highest antibacterial potential against L. innocua (80 mg·mL⁻¹) and E. coli (140 mg·mL⁻¹) than those obtained at lower temperatures. The purification of cellulose from the treated residues, using hydrogen peroxide, revealed that DB is a limited source of cellulose material since the bleached fractions showed low yields (20–25%) and low cellulose purity (42–71%), even after four bleaching cycles (1 h) at pH 12 and 8% H₂O₂. Despite this, the subcritical water extraction method highlights the potential of a simple process as a technological option to convert underutilized side streams like beer bagasse into added-value, potential ingredients for innovative food and pharmaceutical applications. Full article

The endo-1,4-β-xylanases (EC 3.2.1.8) are the largest group of hydrolytic enzymes that degrade xylan, the major component of hemicelluloses, by catalyzing the hydrolysis of glycosidic bonds β-1,4 in this polymer, releasing xylooligosaccharides of different sizes. Xylanases have considerable potential in producing bread, animal feed, food, beverages, xylitol, and bioethanol. The fungus Aspergillus tamarii Kita produced xylanases in Adams’ media supplemented with barley bagasse (brewer’s spent grains), a by-product from brewery industries. The culture extract exhibited two xylanase activities in the zymogram, identified by mass spectrometry as glycosyl hydrolase (GH) families 10 and 11 (GH 10 and GH 11). The central composite design (CCD) showed excellent predictive capacity for xylanase production (23.083 U mL⁻¹). Additionally, other enzyme activities took place during the submerged fermentation. Moreover, enzymatic saccharification based on a mixture design (MD) of three different lignocellulosic residues was helpful in the production of fermentable sugars by the A. tamarii Kita crude extract. Full article

Brewer’s spent grain (BSG) is a residue that holds significant potential for various applications. Given its inherently high moisture levels, it becomes imperative to explore methods for preserving it. This study investigates the use of refractance window (RW) for drying BSG. The final moisture content, water activity, and drying kinetics were assessed. Various kinetic models were analyzed, including Lewis, Page, Overhults, Brooker, and Midilli. Employing a central composite design, this study also investigated the effects of the variables temperature (55.9 to 84.1 °C) and drying time (1.6 to 4.4 h) on the quality of the dried product. The quality was assessed based on the content of bioactive compounds: phenolics, flavonoids, citric acid, and ascorbic acid. The results suggest that refractance window (RW) drying can yield a product with reduced moisture content and water activity levels (lower than 10.0% and 0.600, respectively). The phenolic, flavonoid, and citric acid higher contents were found at 70 °C and 3 to 4 h of drying. The best ascorbic acid results were found at 55 to 65 °C after 3 h of drying. The use of RW emerges as an interesting alternative for processing BSG, offering a sustainable approach to better utilize this residue. Full article

Brewer’s spent grain (BSG) is the main solid waste generated in beer production and primarily consists of barley malt husks. Based on the active promotion of circular economy practices aimed at recycling food industry by-products, this study assessed for the first time the production of particleboards based on BSG as the sole source of lignocellulosic material and natural adhesive without the use of additives or other substrates. In order to achieve particleboards from entirely sustainable sources, BSG particles have to self-bind by thermo-compression with water. In this context, the aim of this study is to assess the effects of pressing temperatures and particle size on properties such as modulus of elasticity, modulus of rupture, internal bond, thickness swelling, and water absorption. The performance of binderless boards was compared with that of a control panel (control) using BSG combined with phenolic resin. Processing conditions were selected to produce boards with a target density of 1000 kg/m³ and a thickness of 5 mm. To confirm the efficiency of the self-adhesion process, scanning electron microscopy was used to examine the boards. The processes of self-adhesion and particle-to-particle contact were facilitated at a pressing temperature of 170 °C and a particle size range of 200–2380 µm (ground BSG), resulting in improved flexural properties and enhanced water resistance. The properties of BSG-based binderless boards were comparable to those reported for other biomass residues, suggesting that they might be used in non-structural applications, such as interior decoration. Full article

Brewer’s spent grain (BSG) is the most abundant residual in the brewing process. Non-starch polysaccharides such as 1,3-1,4-β-D-glucan (β-glucan) and arabinoxylan (AX) with proven beneficial effects on human health remain in this by-product in high amounts. Incorporating the valuable dietary fiber into the food industry could contribute to a healthy diet. However, a major challenge is extracting these dietary fibers (i.e., β-glucan and AX) from the solid residue. In this study, hydrothermal treatment (HT) was applied to dissolve the remaining water-insoluble carbohydrates from BSG with the aim to extract high amounts of β-glucan and AX. Particular focus was placed on the molecular weight (MW) range above 50 kDa and 20 kDa, respectively, as these are considered to have health-promoting effects. Different treatment temperatures, reaction times, and internal reactor pressures were tested to determine the best process settings to achieve high yields of β-glucan and AX and to examine the influence on their molecular weight distribution (MWD). Overall, 85.1% β-glucan and 77.3% AX were extracted corresponding to 6.3 g per kg BSG at 160 °C and 178.3 g kg⁻¹ at 170 °C, respectively. However, less than 20% of both fiber substances were in the desirable MW range above 50 kDa and 20 kDa, respectively. When lower temperatures of 140 and 150 °C were applied, yields of only 3.0 g kg⁻¹ β-glucan and 128.8 g kg⁻¹ AX were obtained, whereby the proportion of desirable fiber fractions increased up to 45%. Further investigations focused on the heat-induced degradation of monosaccharides and the formation of undesirable by-products (i.e., HMF and furfural) that might pose a health risk. Full article

In this study, brewer’s spent grains (BSG)-raw matrix was technologically and functionally improved by adding natural active ingredient carriers (crushed wheat, rapeseed, and pumpkin seed press cake) and using planetary roller extrusion and used as feed additive for pigs. Feeding trials were run for 189 days using 60 pigs with an age of 28 days. Pigs were grouped in a control group (fed with organic basic feed) and two experimental groups (fed with BSG 1 or BSG 2 in addition to organic basic feed). The 20 animals per group gained similar weight in the control group (306 g day⁻¹ and 725 g day⁻¹) and in the group fed with BSG 1 (282 g day⁻¹ and 627 g day⁻¹) or BSG 2 (250 g day⁻¹ 598 g day⁻¹) in addition during rearing and fattening phases, respectively. Carcass evaluation revealed that meat quality did not differ between control and experimental groups. The BSG-based feed formulations tested seem to not result in negative effects on weight gain nor on meat quality. Animals were generally of good health and marketable quality, and thus the outcomes of this study are expected to contribute to an improved utilization strategy of brewer’s spent grains from breweries. Full article

Most agro-industrial wastes are lignocellulosic biomass. Several technologies have been developed to convert these residues to value-added products. Among these processes, pyrolysis refers to the thermal degradation of organic materials. Microwave-assisted pyrolysis (MAP) is more advantageous than conventional pyrolysis because it offers time savings, increases heating efficiency, and promotes a more precise process control. In this work, the microwave-assisted pyrolysis (MAP) of brewer’s spent grain (BSG), the main waste of the brewing industry, was studied, focusing on its liquid product. The effects of temperature, moisture content, and catalyst (calcium oxide) percentage on the product distribution and hydrocarbon content in the liquid product obtained were investigated. Although a high liquid yield of 71.8% was achieved with a BSG moisture content of 14%, the quality of the product (hydrocarbon yield) in this condition was not so attractive (21.60%). An optimization study was carried out to simultaneously maximize bio-oil yield and quality. The optimum conditions obtained were a temperature of 570 °C and a catalyst/biomass ratio of 12.17%. The results of the liquid product composition at the optimum point are promising given the presence of aromatic hydrocarbons, organic compounds of great interest to the industry. Full article

The safety and quality of post-production residues is essential before they can be reused. Both to explore the possibility of reuse as a fermentation medium and the context of pathogens’ inactivation, the research aimed to characterize the fermentation system of L. lactis ATCC 11454 and brewer’s spent grain, malt and barley, especially to in situ inactivation of selected Bacillus strains during the fermentation and storage. Barley products were milled, autoclaved, hydrated and fermented with L. lactis ATCC 11454. Then, the co-fermentation with Bacillus strains was carried out. The amount of polyphenols in the samples ranged from 483.5 to 718.4 ug GAE g⁻¹ and increased after 24 h fermentation with L. lactis ATCC 11454. The high viability of LAB in the fermented samples and after 7 days of storage at 4 °C (8 log CFU g⁻¹) indicates the high nutrients bioavailability during the storage. Also, this co-fermentation on different barley products indicated a high reduction level (2 to 4 logs) of Bacillus due to the biosuppression effect of the LAB strain in this fermentation system. Brewer’s spent grain (BSG) fermented with L. lactis ATCC 25 11454 produces a highly effective cell-free supernatant (CFS) for suppressing Bacillus strains. This was evident in both the inhibition zone and fluorescence analysis of bacteria viability. In conclusion, the obtained results justify the use of brewer’s spent grain in selected food products, increasing their safety and nutritional value. This finding is highly beneficial in the sustainable management of post-production residues when current waste material can still serve as a source of food. Full article

Lignocellulose is a renewable ubiquitous material that comprises cellulose, hemicellulose, and lignin. Lignin has been isolated from different lignocellulosic biomass via chemical treatments, but there has been little or no investigation carried out on the processing of lignin from brewers’ spent grain (BSG) to the best of authors’ knowledge. This material makes up 85% of the brewery industry’s byproducts. Its high moisture content hastens its deterioration, which has posed a huge challenge to its preservation and transportation; this eventually causes environmental pollution. One of the methods of solving this environmental menace is the extraction of lignin as a precursor for carbon fiber production from this waste. This study considers the viability of sourcing lignin from BSG with the use of acid solutions at 100 °C. Structural and thermal analyses were carried out on extracted samples, and the results were compared with other biomass-soured lignin to assess the proficiency of this isolation technique. Wet BSG sourced from Nigeria Breweries (NB), Lagos, was washed and sun-dried for 7 days. Tetraoxosulphate (VI) (H₂SO₄), hydrochloric (HCl), and acetic acid, each of 10 M, were individually reacted with dried BSG at 100 °C for 3 h and designated as H2, HC, and AC lignin. The residue (lignin) was washed and dried for analysis. Wavenumber shift values from Fourier transform infrared spectroscopy (FTIR) show that intra- and intermolecular OH interactions in H2 lignin are the strongest and possess the highest magnitude of hydrogen-bond enthalpy (5.73 kCal/mol). The thermogravimetric analysis (TGA) results show that a higher lignin yield can be achieved when it is isolated from BSG, as 82.9, 79.3, and 70.2% were realized for H2, HC, and AC lignin. The highest size of ordered domains (0.0299 nm) displayed by H2 lignin from X-ray diffraction (XRD) informs that it has the greatest potential of forming nanofibers via electrospinning. The enthalpy of reaction values of 133.3, 126.6, and 114.1 J/g recorded for H2, HC, and AC lignin, respectively, from differential scanning calorimetry (DSC) results affirm that H2 lignin is the most thermally stable with the highest glass transition temperature (T_g = 107 °C). Full article

A circular economy is imperative for environmental sustainability. In this context, biorefineries stand out as a means of production able to reduce the carbon footprint and the impact of global warming. Biorefineries may employ lignocellulosic biomass from various plant sources to produce bioproducts with the potential to replace fossil derivatives through synthesis by microorganisms without competing with food crops. Brewer’s spent grain (BSG), the residue of the brewery production process, is an option with potential for use, being a cheap raw material highly available throughout the year. The chemical composition of this biomass is quite variable, with significant amounts of hemicellulose, mainly consisting of xylose and arabinose monomers that can be technologically converted into value-added products such as xylooligosaccharides, xylitol, second-generation ethanol (2G ethanol), biofilms and furfural. To this end, catalysts are unusual in making biorefineries increasingly competitive in the market, selectively optimizing reactions and reducing the environmental impact of the production processes of these bioproducts. The present review addresses the primary methods for extracting and processing hemicelluloses from BSG using either biocatalysts (enzymes) or homogenous (acids, alkali, and salts) and heterogenous catalysts (solid acids and metal oxide) that can be used to pretreat the biomass and obtain the preferred byproducts. The state of the art of optimized catalysis mechanisms is also presented. Full article