Spent Grain Research Articles

Microbial Fermentation of the Water-Soluble Fraction of Brewers’ Spent Grain for the Production of High-Value Fatty Acids

Brewers’ spent grain (BSG) constitutes the primary by-product of the brewing industry. The valorization of BSG from a circular economy perspective is of high industrial interest. The objective of this study was the exploitation of BSG for the microbial production of branched-chain fatty acids (BCFAs) and polyunsaturated fatty acids (PUFAs), representing two different classes of high-value fatty acids (FAs). In the present study, this waste material underwent treatment with hot water in an autoclave and the resultant extract was utilized for the preparation of a novel liquid medium (BSG medium) to be employed for microbial fermentation. Screening and subsequent scaling-up experiments confirmed the suitability of the BSG medium to support the microbial production of various high-value FAs. In particular, Streptomyces jeddahensis and Conidiobolus heterosporus could be employed for BCFAs production, Pythium ultimum and Mortierella alpina could be used to provide cis-5,8,11,14,17-eicosapentaenoic acid (EPA) and arachidonic acid (ARA), whereas Mucor circinelloides, when grown in a BSG medium, was able to accumulate γ-linolenic acid (GLA).

Effect of the Addition of Brewers’ Spent Grain (BSG) on the Physicochemical and Consumer Liking Attributes of Croatian Indigenous Cooked Sausage “Bijela Krvavica”

This research aimed to investigate the effect of the addition of wet brewers’ spent grains (BSG) on the microbiological safety, and physicochemical and sensory attributes of “bijela krvavica” during seven-day storage at 4 °C. The addition of BSG to the samples of “bijela krvavica” statistically significantly (p < 0.05) affected the mass share of proteins and fat and increased the mass share of water. Increasing the mass share of BSG in “bijela krvavica” did not have a statistically significant (p < 0.05) effect on the mass share of collagen, or on the pH value and aw. Instrumentally determined lightness (L*), redness (a*), and yellowness (b*) showed a decrease with the increase in mass share of wet BSG. Texture profile analysis (TPA) parameters hardness and chewiness also showed a decrease with the increase in BSG share (w = 0–9%) with statistical significance (p < 0.05). The overall liking of “bijela krvavica” samples showed the highest scores for the control sample, while 3% added BSG was rated as second best with no significant difference (p < 0.05). According to the consumer-generated sensory attributes (CATA) scoring, samples with 6 and 9% addition of BSG were described with attributes considered undesirable for meat products, such as “wheaty”, “pale color”, and “poor mouthfeel”. Also, the LogCFUg−1 of enterobacteria, sulfite-reducing clostridia, Staphylococcus aureus, Salmonella spp., and Listeria monocytogenes were not affected. The data obtained in this research indicate the possibility of producing safe “bijela krvavica” sausages with wet brewers’ spent grains without major changes in the physicochemical and sensory properties.

Sequential Extraction and Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy Monitoring in the Biorefining of Brewer's Spent Grain.

The brewing industry plays a significant role in producing a substantial annual volume of by-products, which contributes to the global accumulation of food waste. The primary by-product generated is brewer's spent grain (BSG), a lignocellulosic biomass rich in proteins, fiber, and moisture content. Leveraging biorefining and valorization techniques for BSG represents a promising strategy to enhance sustainability, resilience, and circularity within the brewing chain. To date, most studies have focused on extracting proteins from BSG. Yet, it is crucial to note that the fiber part of BSG also holds considerable potential for biorefining processes. This study introduces a novel sequential extraction method designed to integrally recover the major components of BSG. Notably, it introduces a reactive extraction approach that enables the simultaneous extraction and tuneable functionalization of the hemicellulose component. Additionally, the study assesses the utility of the attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy as a user-friendly tool to monitor and evaluate the effectiveness of the fractionation process. This spectroscopic technique can provide valuable insights into the changes and composition of BSG throughout the extraction process.

Effects of Adherence in the Drying of Brewer’s Spent Grain with Rotating Equipment

Effects of Adherence in the Drying of Brewer’s Spent Grain with Rotating Equipment

Reutilization of Brewer’s Spent Grain as Spent Mushroom Substrate for the Generation of Biogas in a Semi-Continuous Digester

Reutilization of Brewer’s Spent Grain as Spent Mushroom Substrate for the Generation of Biogas in a Semi-Continuous Digester

The Production of Xanthan from Brewer’s Spent Grain

The Production of Xanthan from Brewer’s Spent Grain

Effective Degradation of Brewer Spent Grains by a Novel Thermostable GH10 Xylanase.

Brewer spent grains (BSGs) are one of the most abundant by-products in brewing industry. Due to microbiological instability and high perishability, the efficient degradation of BSGs is of environmental and economic importance. Streptomyces sp. F-3 could grow in the medium with BSGs as the only carbon and nitrogen source. Proteome mass spectrometry revealed that a GH10 xylanase SsXyn10A could be secreted in large quantities. SsXyn10A showed optimum activity at pH 7.0 and 60 °C. SsXyn10A exhibited excellent thermostability which retained approximately 100% and 58% after incubation for 5 h at 50 and 60 °C. SsXyn10A displayed high activity to beechwood xylan (BX) and wheat arabinoxylan (WAX). SsXyn10A is active against xylotetracose (X4), xylopentose (X5), and xylohexose (X6) to produce main products xylobiose (X2) and xylotriose (X3). Ssxyn10A showed synergistic effects with commercial cellulase on BSGs hydrolyzing into soluble sugar. In addition, the steam explosion pretreatment of BSGs as the substrate produced twice as much reducing sugar as the degradation of the original substrate. This study will contribute to efficient utilization of BSGs and provide a thermostable GH10 xylanase which has potential application in biomass hydrolysis.

Versatile Applications of Brewer's Spent Grain: Solid-State Fermentation and Nutritional Added Value.

Brewer's spent grain (BSG) is a major by-product in the beer-brewing process which contributes to 85% of the entire generated by-product in the brewing process. BSG is rich in proteins, and most of the malt proteins (74-78%) remain insoluble in BSG after the mashing process. Solid-state fermentation (SSF) is a promising bioprocess that enables microorganisms to survive in environments with minimal water and has shown to enhance the nutritional composition of BSG. In this review, the potential application of protein, amino acids (proline, threonine, and serine), phenolic contents, and soluble sugars (glucose, fructose, xylose, arabinose, and cellobiose) extracted from BSG by various microorganisms using SSF is explored. Incorporation of BSG into animal feed, human diets, and as a substrate for microorganisms are the prospects that could be implemented in the industrial scale. This review also discussed various advances to improve the fermentation yield such as symbiotic fermentation, the addition of nitrogen supplements, and an optimal mixture of the agro-industrial waste substrate. Future perspectives on SSF are also addressed to provide important ideas for immediate and future studies. However, challenges include optimizing SSF conditions and design of bioreactors, and operational costs must be addressed in the future to overcome current obstacles. Overall, this mini review highlights the potential benefits of BSG utilization and SSF in a sustainable way.

Combinations of Spent Grains as Sources of Valuable Compounds with Highly Valuable Functional and Microbial Properties

The potential of spent grains as a source of valuable compounds with various properties has gained attention. They are the by-product of the brewing process, typically resulting from the beer-making process. Five different mixed combinations of spent grains of barley, wheat, rice, maize and finger-millet were formulated and further analyzed and compared. Barley and wheat (BW), barley and rice (BR), barley and maize (BM), and barley and finger-millets (BF) were mixed in a ratio of 1:1 (w/w) and ground into a fine powder to study their techno-functional, phytochemical and in vitro properties. The techno-functional, phytochemical and in vitro properties of barley and maize (BM) were found to be the best choice, making it a promising candidate for applications in value-added products. The WAI (water absorption index) of BM (5.03 g/g) was the highest compared to BB (3.20 g/g), BF (3.56 g/g), BR (4.10 g/g) and BW (4.33 g/g), whereas the WSI (water solubility index) and OAC (oil absorption capacity) of BM (7.06% and 1.90 g/g, respectively) were lower than BW (7.60% and 2.24 g/g, respectively), BR (8.20% and 2.30 g/g, respectively), BF (9.67% and 2.57 g/g, respectively) and BB (10.47% and 2.70 g/g, respectively). A higher percentage of inhibition of DPPH (44.14%) and high phenolic and flavonoid contents (72.39 mg GAE/gm and 66.03 mg QE/gm, respectively) were observed in BM. It also showed higher in vitro properties like amylase and lipase inhibition assay (89.05% and 62.34%, respectively) than the other combinations. The present study provides valuable information about the differences between spent grain varieties and their combinations, with potential applications in various industries.

Enhancing Fertilizer Effect of Bioprocessed Brewers’ Spent Grain by Microbial Consortium Addition

Brewers’ spent grain (BSG) is primarily recycled as livestock feed due to its high fiber content, undegradable protein, and water-soluble vitamins. However, BSG composting represents a possible alternative to organic waste management. Adding a microbial consortium further enhances the agronomical properties of the compost intended for fertilizing applications. Microbial-based fertilizers (plant growth-promoting microorganisms, PGPM) are a means to mitigate the adverse environmental impacts of excessive or improper chemical fertilizer use, enhance the direct or indirect uptake of nutrients by plants, and add value to food waste. In a short-term pot experiment on iceberg lettuce (Lactuca sativa L.), this study assessed the effects of compost and pelletized compost from brewers’ spent grain, both enriched with a microbial consortium. In a randomized block experiment, this study compared four organic BSG fertilizers to chemical fertilizer (NPK) and an unfertilized control treatment. The investigation indicates that BSG compost and BSG pelleted compost, with and without bio-inoculum, in general, are comparable to mineral fertilizer treatment; lettuce fresh weight was higher in pots amended with bioprocessed BSG, associated with more significant growth of soil LAB, fungi, and actinomycetes. The investigation outcomes support composting as an alternative recycling process for producing PGM for agricultural applications.

Influence of Hydrothermal Treatment of Brewer's Spent Grain on the Concentration and Molecular Weight Distribution of 1,3-1,4-β-D-Glucan and Arabinoxylan.

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.

The Rheology and Textural Properties of Bakery Products Upcycling Brewers' Spent Grain.

This study aimed to evaluate the rheological properties of doughs with 50% brewers' spent grain (BSG) derived from a rye-based (RBSG) and barley-based (BBSG) beer added, and the textural profile of the related baked products. Simple model systems using BSG flour mixed with water were studied. Two bakery products, focaccia and cookies, were made as food systems using BSG in a 1:1 ratio with wheat flour (WF). Their rheological properties and texture after baking were characterized. BSG-added dough exhibited viscoelastic properties with a solid gel-like behavior. The addition of BSG increased G' > G″ and decreased the dough flexibility. BSG addition in baked RBSG focaccia increased the hardness, gumminess, and chewiness by 10%, 9%, and 12%, respectively. BBSG cookies had a 20% increase in fracturability. A positive correlation was found between the rheological metrics of the dough and the textural parameters of BBSG-added cookies. PCA analysis revealed that complex viscosity, G', G″, and cohesiveness separated BBSG focaccia from RBSG focaccia and the control. Therefore, the rheological properties of BSG dough will have industrial relevance for 3D-printed customized food products with fiber. Adding RBSG and BBSG to selected foods will increase the up-cycling potential by combining techno-functional properties.

Quality of biogas generated through co-digestion of Brewer’s spent grain and cattle dung

Anaerobic Digestion (AD) of mono-substrate is reported to be ineffective due to nutritional imbalance and lack of a variety of microbes. Anaerobic co-digestion of substrates is the advised alternative to mono-digestion to boost the generation of quality biogas. Brewers’ Spent Grains (BSG) contain high organic matter content and can be used in the production of biogas towards reducing the reliance on fossil fuel-based energy sources. Biogas generation from BSG can be improved through the co-digestion process via the inclusion of extra substrate. The current study explored the quality of biogas generated through co-digestion of BSG and cattle dung (CD). Digestion of two substrates was managed at a retention time of 10 days at BSG: CD ratios: 1:3, 1:2, 1:1, 2:1, 3:1, BSG and CD control experiments with substrates combination of 4.5 kg in each setup. Plastic bottles (10 L) were used as bio-digesters with substrates and water at a 1:1 ratio to allow anaerobic digestion (AD) to proceed. Results showed that BSG: CD ratios of 1:3 and 1: 2 with total solids (TS) content of 9.24% and 8.95% produced the highest quality raw biogas rich in methane. Both ratios 1:3 and 1:2 produced Methane which exhibited a 100% lower explosive limit (LEL) at an average of 40.3 ± 29.88 % LEL d−1 and 40.28 ± 33.39 LEL d−1 respectively; with a respective methane content of 54.7 ± 10.74% CH4d−1 and 51.9 ± 8.67% CH4d−1. The current study provides a facile and convenient optimal ratio between BSG and CD for the production of high-quality biogas using environmentally prevalent materials.

Utilization of Brewer’s Spent Grains and Agricultural Residues in Pig Feed Formation

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.

Sustainable Bioprocess Combining Fed-Batch Pretreatment Followed by Semi-Continuous Anaerobic Digestion of Brewer’s Spent Grains for Biomethane Production

Sustainable Bioprocess Combining Fed-Batch Pretreatment Followed by Semi-Continuous Anaerobic Digestion of Brewer’s Spent Grains for Biomethane Production

Potential of Nanocellulose as a Dietary Fiber Isolated from Brewer's Spent Grain.

Steady growth in beer production is increasing the number of by-products named brewers' spent grain. Such by-products are a source of several components, where cellulose is usually present in high amounts. The aim of this study was to develop a protocol to obtain a mix of cellulose microfibers with an average diameter of 8-12 µm and cellulose nanoplatelets with an average thickness of 100 nm, which has several applications in the food industry. The process comprised one alkaline treatment followed by acid hydrolysis, giving a new mix of micro and nanocellulose. This mix was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and laser scanning microscopy corroborating the presence and measurements of the cellulose nanostructure, showing an aspect ratio of up to 500. Finally, we demonstrated that the administration of this new type of nanocellulose allowed us to control the weight of mice (feed intake), showing a significant percentage of weight reduction (4.96%) after 15 days compared with their initial weight, indicating the possibility of using this material as a dietary fiber.

Biodegradable Composite Film of Brewers’ Spent Grain and Poly(Vinyl Alcohol)

Plastic pollution and food waste are two pressing global challenges that require immediate attention and innovative solutions. In this study, we address these challenges by upcycling brewers’ spent grain (BSG) into biodegradable composite films. BSG, a by-product of the beer brewing process, is commonly discarded in landfills or used as animal feed. By utilizing BSG as a raw material for biodegradable films, we simultaneously reduce waste and decrease plastic pollution. To create the composite films, we employed poly(vinyl alcohol) (PVA) and glycerol as binder materials, along with hexamethoxymethylmelamine (HMMM) as a water-repelling agent. By varying the ratios of these components, we investigated the effects on film properties. Our characterization included assessing moisture uptake and tensile properties. The results revealed that the practical BSG content in the films was 20–60 wt%. Films with this composition exhibited a balance between moisture absorption and mechanical strength. The addition of glycerol improved the flexibility and toughness of the films, while HMMM reduced moisture absorption, enhancing their water resistance. This study contributes to the development of sustainable materials by showcasing the potential of upcycling BSG into valuable biodegradable films. By transforming food waste into useful applications, we reduce environmental burdens and promote a circular economy. Further research is warranted to explore the potential applications and optimize the properties of BSG-based composites.

Brewer’s Spent Grain with Yeast Amendment Shows Potential for Anaerobic Soil Disinfestation of Weeds and Pythium irregulare

Anaerobic soil disinfestation (ASD) is a promising alternative to chemical fumigation for controlling soilborne plant pathogens and weeds. This study investigated the impact of brewer’s spent grain (BSG), a locally available carbon source, on various weed species and the oomycete pathogen Pythium irregulare in ASD. Two greenhouse studies were conducted using BSG and yeast at full and reduced rates in a completely randomized design with four replicates and two runs per study. In both studies, ASD treatments significantly decreased the seed viability of all weed species and the Pythium irregulare inoculum, while promoting higher cumulative anaerobicity compared to the non-treated control. The addition of yeast had a notable effect when combined with BSG but not with rice bran. When used in reduced carbon rates, yeast supplementation enhanced the efficacy of BSG, providing comparable control to the full rate for most weed species, including redroot pigweed, white clover, and yellow nutsedge. Interestingly, no ASD treatment affected the soil temperature. Furthermore, BSG treatments caused higher concentrations of volatile fatty acids compared to ASD with rice bran and the non-treated control. This finding suggests that the inclusion of yeast in ASD shows potential for reducing the carbon input required for effective soil disinfestation.

Effect of Dietary Substitution of Wheat Bran with Dried Brewer’s Spent Grains on Performance and Economics of Growing Crossbred Pigs

Background: Brewers spent grains (BSG), may offer a suitable cheap replacer for traditional feedstuffs. The present study investigated the effect of dietary substitution of wheat bran with BSG on performances and production economics of crossbred grower pigs . Methods: The current study was conducted on sixty crossbred pigs (28 male + 32 female) that were randomly divided into four groups and allotted to dietary treatment replacement by 0% (T0), 25% (T1), 50% (T2) and 100% (T3) dried BSG against conventional wheat bran in pig ration. Results: Results indicated significant (P less than 0.05) improvement in the total body weight gain and average daily gain (ADG) in both male and female crossbred pigs in groups T0, T1 and T2 when compared against T3. The performances of the both female and male pigs were significantly (P less than 0.05) lower when dietary levels of BSG were increased up to 100 % (T3). Group T3 had significantly (P less than 0.01) lower carcass traits as compared to the other groups. The feed cost/kg live weight gain in T2 was significantly (P less than 0.05) lower than the control group in both the sexes. In conclusion, crossbred pigs can tolerate up to 50% substitution of wheat bran with BSG and is cost-effective.

Adsorption behavior of reactive Red 24 and methylene blue onto Brewer’s spent grain: characterization, kinetics, and isotherms modeling

ABSTRACT Dyestuff wastes, made by the textile, paper, and dye industries, stay in the waste environment because they resist chemical and biological degradation. Treating industrial effluent to remove pollutants and lessen their effects before releasing them into the environment is crucial. Malt bagasse (BSG; Brewer’s Spent Grain) from a local brewery was used as an adsorbent for the textile industry dyes Methylene Blue (MB) and Reactive Red 24 (RR24). The adsorption of MB and RR24 was conducted at pH 7.00 and 1.50, respectively. While the temperature change had little effect on the MB adsorption process and capacity, the RR24 adsorption rate was increased without affecting the capacity. Both dyes’ adsorption mechanisms better fit the Langmuir isotherm and pseudo-second-order kinetic models. The maximum adsorption capacity was 80.31 mg/g for MB and 100.52 mg/g for RR24. Experiments using simulated wastewater indicated that the matrix did not significantly affect the efficiency with which RR24 and MB were removed. The findings suggest that BSG is a promising alternative adsorbent that is inexpensive, accessible, and simple to obtain.