Search Results (22)

In this research, novel biocomposite filaments were developed by incorporating coffee silver skin (CSS) waste into polylactic acid (PLA) for use in Fused Filament Fabrication (FFF) technology. CSS was blended with PLA at concentrations of 0, 5, 10, and 15 wt.% to address the waste disposal challenge and produce environmentally friendly composite biofilaments for FFF, supporting circular economic efforts. These filaments have the potential to be used in sustainable prototyping, functional parts, and consumer products. A comprehensive analysis was conducted to examine the effect of printing temperature on dimensional accuracy, melt flow index (MFI), and mechanical properties. Higher printing temperatures and increased CSS content led to larger dimensions due to increased material fluidity, as confirmed by MFI results, which increased from 3.5 g/10 min (0% CSS) to 5.8 g/10 min (15% CSS) at 180 °C, reaching 26.3 g/10 min at 220 °C. Tensile tests on 3D-printed specimens indicated an improvement in elastic modulus with increasing CSS content at lower temperatures (180 °C), rising from 1622 MPa (0% CSS) to 1952 MPa (15% CSS), representing about a 20% increase. However, at higher temperatures, the elastic modulus decreased, possibly due to the poor dispersion and agglomeration of filler particles. Tensile strength generally decreased with CSS addition, especially at higher loadings, while yield elongation remained low (~1.4–1.7%), indicating a more brittle material. The findings also revealed no significant thermal changes with increasing CSS content, and good printability was achieved for all compositions, which was characterized by good layer adhesion, the absence of warping, and the ease of extrusion. Full article

Coffee and cocoa agribusinesses generate large volumes of byproducts, including coffee husk, coffee pulp, parchment skin, silver skin, and cocoa bean shell. Despite the rich composition of these materials, studies on biomolecule extraction with green solvents are still scarce, and further research is needed. Extraction methods using alternative solvents to obtain biomolecules must be developed to enhance the byproducts’ value and align with biorefinery concepts. This article reviews the compositions of coffee and cocoa byproducts, their potential applications, and biomolecule extraction methods, focusing on alternative solvents. The extraction methods currently studied include microwave-assisted, ultrasound-assisted, pulsed electric field-assisted, supercritical fluid, and pressurized liquid extraction. At the same time, the alternative solvents encompass the biobased ones, supercritical fluids, supramolecular, ionic liquids, and eutectic solvents. Considering the biomolecule caffeine, using alternative solvents such as pressurized ethanol, supercritical carbon dioxide, ionic liquids, and supramolecular solvents resulted in extraction yields of 2.5 to 3.3, 4.7, 5.1, and 1.1 times higher than conventional solvents. Similarly, natural deep eutectic solvents led to a chlorogenic acid extraction yield 84 times higher than water. The results of this research provide a basis for the development of environmentally friendly and efficient biomolecule extraction methods, improving the utilization of agricultural waste. Full article

Seeking food-derived antioxidants and inhibitors of α-glucosidase and α-amylase has been recognized as an effective way for managing diabetes. Coffee silver skin (CSS) is rich in phenolic compounds, which may be potential agents as antioxidants and for α-glucosidase and α-amylase inhibition. But whether phenolics in different forms show similar bioactivity remains unknown. In this study, phenolic compounds in CSS were extracted as free phenolics (FPs), esterified phenolics (EPs), and bound phenolics (BPs). The phenolic profiles and antioxidant activities of them were investigated. Their inhibitory effects on α-glucosidase and α-amylase were analyzed, and the inhibitory mechanisms were elucidated by molecular docking and molecular dynamic simulation. Results showed that FPs exhibited the best antioxidant ability and inhibitory effects on α-glucosidase and α-amylase. A total of 17 compounds were identified in FPs with 3-caffeoylquinic acid, 4-feruloylquinic acid, and dicaffeoylquinic acids as the dominant ones. Typical phenolics in FPs could bind to α-glucosidase and α-amylase through hydrogen bonds and form hydrophobic interaction with several key amino acid residues. In addition, 3,4-dicaffeoylquinic acid and 3-caffeoylquinic acid might be the principal components that account for the inhibitory effect of FPs on α-glucosidase. The results of this study may provide some scientific support for CSS utilization as a health-beneficial component in functional food development for type 2 diabetes mellitus management. Full article

The goal of the research was to determine the impact of fortification with polyphenolic compounds on (i) sensory attractiveness (global satisfaction, appearance, colour, odour, flavour, sweetness, bitterness), (ii) content of polyphenols and colour (L*, a*, b*) after the baking process and (iii) their bioactive potential (antioxidants activity and inhibiting of α-amylase and α-glucosidase enzyme). Fortification was made with extracts of polyphenolic compounds of selected plant raw materials rich in polyphenols from quince (fruits), tilia (flowers), pomegranate (skin), passion fruit (endocarp), sour cherries (leaves), haskap and chokeberry (berries), silver skin (coffee beans), rosehip (seeds). Depending on the nature of the polyphenol extract, flavan-3-ols (monomeric and polymeric), phenolic acid, flavonols and anthocyanins were identified in the product in amounts ranging from 53.7 to 212.6 mg/100 g DM. Cookies’ colour (L*, a*, b*) depended on the type of polyphenol extract used for fortification. Cookies with haskap, chokeberry and sour cherry presented the highest antioxidant potential. Cookies with chokeberry, haskap and rosehip presented high activity in inhibiting α-amylase (65.5, 60.6 and 62.2% of inhibition, respectively), but cookies with haskap, silver skin and quince in inhibiting α-glucosidase activity (23.0, 20.4 and 21.4% of inhibition, respectively). In the sensory evaluation, the most attractive were cookies with rosehip and pomegranate (6.3 and 5.8 score, respectively), but the lowest ratings were given to cookies with passion fruit and silver skin but especially quince cookies, which obtained the lowest desirability (3.7 score). The acceptability of fortified cookies was determined to the least extent by monomeric flavan-3-ols and phenolic acids (in minus in odour/flavour, bitterness, sweetness and global satisfaction), but anthocyanins, polymeric procyanidins and flavonols had the most significant positive impact on consumer acceptance of the assessed features, i.e., global satisfaction, odour/flavour, sweetness and bitterness (positive consumer drivers). Full article

Brain–gut axis disorders, such as functional dyspepsia and irritable bowel syndrome (traditionally known as functional gastrointestinal disorders), have a prevalence of more than 10% in most countries and affect females more than males. In these disorders, visceral pain and motor alterations affecting the gastrointestinal tract are the key symptoms, together with psychoaffective alterations (depression and anxiety). Two main etiologies are generally recognized for their development: they may be caused by a local inflammatory or infectious problem in the gastrointestinal tract that sensitizes the visceral afferents and lead to central hypersensitization; alternatively, they may be associated with some kind of prolonged psychological stress in vulnerable people or vulnerable periods of life (i.e., due to early life stress). In recent years, studies have focused on the effects of coffee, its components (melanoidins) and its by-products (e.g., coffee spent grounds and coffee silver skin derivatives) on the functions of the brain–gut axis, showing that these products may cause subtle alterations in gastrointestinal motility, visceral sensitivity and behavioral parameters, in a sex-dependent manner. For example, using male rats, we showed that melanoidins and coffee spent grounds slightly accelerate gastrointestinal transit in vivo. In contrast, the regular consumption of instant cascara (IC) did not alter GI transit or behavior in either male or female rats in vivo, but increased both the responses to mechanical intracolonic stimulation and the non-muscarinic responses to electrical field stimulation of the colonic muscle in vitro, specifically in females. These effects need to be taken into account when new functional foods based on coffee and its by-products are to be developed for the general population. Considering the high prevalence of the brain–gut axis disorders and its higher impact on women, with significant symptoms affecting visceral sensitivity and bowel habits, the effects of coffee components and by-products need to be more deeply evaluated in both relevant animal models of brain–gut axis disorders and in clinical trials. Full article

The development of fully renewable and biodegradable composites for short-term applications was pursued by combining a compatibilized poly(lactic acid) (PLA)/poly(butylene succinate-co-adipate) (PBSA) (60:40 wt:wt) blend with coffee silver skin (CSS), an industrial byproduct from coffee processing. An epoxy-based reactive agent (Joncryl ADR-4468) was added as a compatibilizer. CSS was incorporated at 5, 10, and 20 wt% in the blend both in the as-received state and after a simple thermal treatment in boiling water, which was performed to mitigate the negative impact of this filler on the rheological and mechanical properties of the blend. The CSS treatment effectively increased the filler degradation temperature of 30–40 °C, enabling stable melt processing of the composites. It also improved filler–matrix adhesion, resulting in enhanced impact properties (up to +172% increase in impact energy compared to the untreated filler). Therefore, treated CSS demonstrated potential as an effective green reinforcement for PLA/PBSA blends for rigid packaging applications. Future works will focus on studying suitable surface modification of CSS to further increase the interfacial interaction and the tensile quasi-static properties, to fully exploit the capabilities of this renewable material toward the development of eco-friendly composites. Full article

The Sustainable Development Goals (SDG) encourage the efficient use of sustainable technologies. Ultrasound-assisted extraction (UAE) is one of the extraction process techniques, which are also directed towards sustainability as a goal. Coffee silver skin (CS), being a healthy raw material as well as a waste, could be utilized in the manufacturing process of new dietary products. The goal of this research was to isolate proteins and polyphenols from CS using UAE and to employ spectrophotometry to determine the yields. Three parts of the research were conducted: ultrasonic extraction, the optimization of UAE conditions for the isolation of proteins and polyphenols from CS, and the analysis of the amino acid extract obtained with the optimal use of UAE. According to the results, it was reported that the highest yields of total polyphenols isolated from the CS using UAE were obtained by applying an amplitude of 75% and a time interval of 9 min. The optimal parameters of UAE, when considering the proportions of total polyphenols and proteins, are an amplitude of 100% and a time of 9 min. The most abundant amino acids in isolated proteins (Asp, Glu, Pro, Gly, and Ala) were defined as well. Based on the use of energy, it was obvious that UAE is a promising technology. This concurs with the proposed practice that when non-thermal technologies are analyzed from an environmental point of view, the first common denominator is the use of electricity to run the equipment, in relation to resource depletion. As expected, CS poses a great waste to be recycled, being a nutritionally rich raw material with great potential. Quantitative consideration on the environmentally friendly applicability of CS in mass production should be carried out to validate the entire process of developing a new product from both economic and environmental aspects. Full article

Trigonelline is a bioactive pyridine alkaloid that occurs naturally in high concentrations in coffee (up to 7.2 g/kg) and coffee by-products (up to 62.6 g/kg) such as coffee leaves, flowers, cherry husks or pulp, parchment, silver skin, and spent grounds. In the past, coffee by-products were mostly considered waste and discarded. In recent years, however, the use of coffee by-products as food has attracted interest because of their economic and nutritional value and the environmental benefits of sustainable resource use. Their authorization as so-called novel foods in the European Union may lead to increased oral exposure of the general population to trigonelline. Therefore, the aim of this review was to assess the risk to human health of acute and chronic exposure to trigonelline from coffee and coffee by-products. An electronic literature search was performed. Current toxicological knowledge is limited, with few human data available and a lack of epidemiological and clinical studies. There was no evidence of adverse effects after acute exposure. No conclusion can be drawn on chronic exposure to isolated trigonelline due to the lack of data. However, trigonelline ingested as a component of coffee and coffee by-products appears to be safe for human health, based on the safe traditional use of these products. Full article

The aim of this research was to evaluate the health safety (concentrations of pesticide residues and heavy metals) and nutritional parameters (macro- and microminerals and crude fibre) of coffee silver skin (CS), as well to isolate proteins from this by-product using an optimised microwave extraction method. The CS by-product samples showed the highest amount of potassium, followed by calcium, magnesium, and sodium. Iron was found in the highest quantity among the microminerals, followed by copper, manganese, zinc, and chromium. The CS sample showed a large amount of fibre and a moderate quantity of proteins obtained by the optimised microwave extraction method. Four heavy metals (nickel, lead, arsenic, and cadmium) were detected, and all were under the permitted levels. Among the 265 analysed pesticides, only three showed small quantity. The results for the proteins extracted by microwave showed that the total protein concentration values ranged from 0.52 ± 0.01 mg/L to 0.77 ± 0.07 mg/L. The highest value of the concentration of total proteins (0.77 ± 0.07 mg/L) was found in the sample treated for 9 min, using a power of 200 W. Based on these results, it can be concluded that CS is a healthy and nutritionally rich nutraceutical that could be used in the production of new products in the food industry and other industries. Full article

Bio-composites have been formulated by exploiting post-industrial PLA derived from thin film production and silver skin, a by-product of the coffee’s roasting process. The mix design for the compounds exploits the effects of regrading and toughening agents. The mechanical properties of the materials have been investigated as well as the thermal and physical ones. The recycled material mixed with the regrading additive shows good mechanical properties. The filler addition increases the elastic modulus of PLA up to a 20% but decreases the mechanical properties (about 20% on tensile strength), leading to a brittle behavior (minus 35% of impact strength). The use of a toughening agent restores the plastic deformation ability of the matrix. Full article

Coffee protein is reported to have high levels of branched-chain amino acids of value in sports nutrition and malnutrition recovery. However, data demonstrating this unusual amino acid composition are limited. We investigated the extraction and isolation of protein concentrates from coffee bean fractions, viz. green coffee, roasted coffee, spent coffee and silver skin, and determined their amino acid profile, caffeine content and protein nutritional quality, polyphenol content and antioxidant activity. Alkaline extraction/isoelectric precipitation gave lower concentrate yields and protein content than alkaline extraction/ultrafiltration. The protein concentrate from green coffee beans had a higher protein content than those from roasted coffee, spent coffee and silver skin, regardless of extraction method. The isoelectric precipitated green coffee protein concentrate had the highest in vitro protein digestibility and in vitro protein digestibility corrected amino acid score (PDCAAS). Silver skin protein concentrate had a very low digestibility and in vitro PDCAAS. In contrast to a previous finding, the amino acid levels in all coffee concentrates did not demonstrate high levels of branched-chain amino acids. All protein concentrates had very high levels of polyphenols and high antioxidant activity. The study suggested investigating coffee protein’s techno-functional and sensory attributes to demonstrate their potential applications in different food matrices. Full article

Roasted coffee silver skin is a coffee by-product, the uses of which are currently limited, e.g., as fertilizer, for energy production, or animal feed. Due to a low content of fat and carbohydrates combined with a high content of fiber, polyphenols and proteins, roasted silver skin is a valuable possible food ingredient. Potential applications include partial flour replacement in bakery products, as antioxidant and providing protein or fiber sources in sports or functional foods. As no relevant consumption of isolated silver skin occurred before 1997 in the European Union (EU), it was classified as a novel food in need of premarketing approval. Novel food applications must meet legal requirements for compositional and toxicological information. This review presents information on silver skin composition and toxicological studies. Several in vitro studies and subchronic in vivo studies are available with negative results, not suggesting a need for further studies on carcinogenic effects, reproduction, or chronic toxicity. All available studies so far concluded that no toxic effects of silver skin were found or are to be expected. For a novel food application in the EU, further in vitro studies on mutagenic potential may be needed to close a formal data gap. Full article

Coffee, as one of the most traded resources, generates a vast amount of biogenic by-products. Coffee silver skins (CSS), a side stream from the roasting process, account for about 4 wt.%. Despite the abundancy of CSS, possible routes to generate added value for broad applications are limited. Herein, we present an approach to use CSS as a precursor material for supercapacitor electrodes. KOH activated carbon (AC) was produced from CSS. The resulting AC—CSS was characterized by X-ray diffraction, gas sorption analysis, scanning electron microscopy, and Raman spectroscopy. The highly porous AC—CSS exposes a specific surface area of more than 2500 m² g⁻¹. Electrodes formed with AC—CSS were electrochemically characterized by performing cyclic voltammetry and galvanostatic cycling. The electrodes were further assembled into a supercapacitor device and operated using 1 M sulfuric acid as electrolyte. In addition, various quinones were added to the electrolyte and their impact on the capacitance of AC—CSS electrodes was analyzed. In this work, we were able to show that CSS are a valuable source for supercapacitor applications and that coffee-waste-derived quinones can act as capacitance enhancers. Thus, the findings of this research show a valuable path towards sustainable and green energy storage solutions. Full article

Not all the coffee produced goes to the roasting stage, because non-compliant green coffee beans are usually discarded by roasters and the silverskin of the coffee is usually removed and discarded. In the present work, non-compliant green coffee beans and coffee silverskins were fully characterized from a chemical point of view. In addition, enzyme-assisted extraction was applied to recover a fraction rich in proteins and polyphenols, tested for antimicrobial, antityrosinase, and antioxidant activities. Non-compliant green coffee beans showed higher amounts of polyphenols, flavanols, flavonoids, and caffeine than coffee silverskins (which were richer in tannins). The enzymatic extraction of non-compliant coffee green beans produced extracts with a good protein content and with a consistent quantity of polyphenols. The extract showed antioxidant, antityrosinase, and antimicrobial activity, thus representing a promising strategy to recover defective green coffee beans. The antioxidant and antimicrobial activity of coffee silver skins is lower than that of non-compliant coffee green beans extracts, while the antityrosinase activity is comparable. Full article

The coffee plant Coffea spp. offers much more than the well-known drink made from the roasted coffee bean. During its cultivation and production, a wide variety of by-products are accrued, most of which are currently unused, thermally recycled, or used as animal feed. The modern, ecologically oriented society attaches great importance to waste reduction, so it makes sense to not dispose of the by-products of coffee production but to bring them into the value chain. The aim of this presentation is to provide an updated overview of novel coffee products in the food sector and their current legal classification in the European Union (EU). Coffee flowers, leaves, cascara, coffee cherry spirit, silver skin, and coffee wood are among the materials considered in this article. Some of these products may have, at least, an indirect history of consumption in Europe (silver skin), while others have already been used as traditional foods in non-EU-member countries (coffee leaves, flowers, cascara, and coffee cherry spirit). Of these, coffee leaf tea and cascara have already been approved by the European Commission. Following a consultation with EU member states, spent coffee grounds were determined as being not novel. For the other products, toxicity and/or safety data need to be gathered to further advance novel food applications. Full article