Spent Brewer Research Articles

Rejuvenated Brewer's Spent Grain: The impact of two BSG-derived ingredients on techno-functional and nutritional characteristics of fibre-enriched pasta

Brewer's Spent Grain (BSG), rich in fibre and protein is mostly used for animal feed but has great potential to be used as an ingredient for cereal based products. Originated from BSG, the two ingredients EverVita Fibra (EVF) high in fibre; and EverVita Pro (EVP) high in protein, were used to produce fibre-enriched pasta and compared to semolina, wholemeal flour and a commercial fibre-rich pasta. Analysis of gluten network development and pasting properties revealed the formation of a stronger network by the incorporation of EVP resulting in a compact pasta structure which led to a higher pasta firmness and tensile strength and a decrease in predicted glycaemic index compared to the controls. EVF resulted in an inferior product compared to EVP but was comparable to the semolina control. Hence, EVF and EVP have the potential to increase nutritional value of pasta while maintaining or even improving pasta quality and encouraging the recycling of by-streams for food production.

Spent Brewer's Yeast as a Source of Insoluble β-Glucans.

In the brewing process, the consumption of resources and the amount of waste generated are high and due to a lot of organic compounds in waste-water, the capacity of natural regeneration of the environment is exceeded. Residual yeast, the second by-product of brewing is considered to have an important chemical composition. An approach with nutritional potential refers to the extraction of bioactive compounds from the yeast cell wall, such as β-glucans. Concerning the potential food applications with better textural characteristics, spent brewer’s yeast glucan has high emulsion stability and water-holding capacity fitting best as a fat replacer in different food matrices. Few studies demonstrate the importance and nutritional role of β-glucans from brewer’s yeast, and even less for spent brewer’s yeast, due to additional steps in the extraction process. This review focuses on describing the process of obtaining insoluble β-glucans (particulate) from spent brewer’s yeast and provides an insight into how a by-product from brewing can be converted to potential food applications.

Membrane Fractionation of Protein Hydrolysates from By-Products: Recovery of Valuable Compounds from Spent Yeasts

Spent brewer’s yeast (Saccharomyces sp.), the second most generated by-product from the brewing industry, contains bioactive and nutritional compounds with high added value such as proteins (40–50%), polysaccharides, fibers and vitamins. Molecules of interest from agro-industrial by-products need to be extracted, separated, concentrated, and/or purified so that a minimum purity level is achieved, allowing its application. Enzymatic hydrolysis has been successfully used in the production of peptides and protein hydrolysates. The obtained hydrolysates require efficient downstream processes such as membrane technology, which is an important tool for the recovery of thermolabile and sensitive compounds from complex mixtures, with low energy consumption and high specificity. The integration of membrane techniques that promote the separation through sieving and charge-based mechanisms is of great interest to improve the purity of the recovered fractions. This review is specifically addressed to the application of membrane technologies for the recovery of peptides from yeast protein hydrolysates. Fundamental concepts and practical aspects relative to the ultrafiltration of agro-industrial protein hydrolysates will be described. Challenges and perspectives involving the recovery of peptides from yeast protein hydrolysates will be presented and thoroughly discussed.

Effects of oxidising atmosphere on brewer’s yeast hydrothermal treatment and subsequent biopolymer recovery

• The presence of oxygen enhanced yeast disintegration. • Soluble proteins abated at long times when oxygen was present. • Oxygen caused a convergency in the different protein isoelectric points to 3. • Oxygen decreased protein hydrophobicity, worsening saline precipitation. • Oxygen reduced protein recovery but enhanced selectivity in IMAC. Spent brewer’s yeast is an underused by-product, whose current management offers low returns. This article studies, for the first time ever, the hydrothermal treatment of spent brewer’s yeast, paying special attention to the effect of the presence of oxygen on the physical properties, composition and potential recovery of valuable products from the hydrolysed yeast, as previous step towards the employment of these recovered proteins as renewable chemical feedstock for green industrial uses. Results showed a higher VSS disintegration employing an oxidising atmosphere, as well as a better solubilisation in terms of solid COD reduction, although it also lowered soluble COD but without significantly reducing soluble TOC. Both treatments led to an almost complete solubilisation of protein and carbohydrates from yeast, which were subsequently degraded in presence of oxygen if reaction times were lengthened. Looking at biopolymer recovery, protein precipitation by pH adjustment worked better in hydrolysates obtained in presence of oxygen, with almost 90% of protein precipitation and good selectivities at pH 2.5 and 3. Salting out was more effective, in terms of selectivity, for samples obtained in absence of oxygen and low concentrations of ammonium sulphate. The application of IMAC showed better results on yeast hydrolysates obtained under an inert atmosphere, reaching maximum sorption capacities of almost 100 mg protein/g dry resin, three times higher than those observed using the hydrolysate produced in presence of oxygen. A new perspective in yeast management during beer production is open as renewable chemical feedstock for protein, although further studies are required to optimise protein recovery and purification with respect to its applications.

Spent brewer’s yeast proteins and cell debris as innovative emulsifiers and carrier materials for edible oil microencapsulation

Spent brewer's yeast is a by-product rich in proteins, polysaccharides, and fibres. In addition to being nutritive, this material is available in large amounts and can be considered a cheap and sustainable alternative as a carrier material for microencapsulation. The objective of this work was to use the protein hydrolysate of spent brewer's yeast as an emulsifying agent and carrier material for the microencapsulation of sunflower oil by spray drying. A Central Composite Rotational Design (CCRD) was used to determine emulsion's optimal conditions: protein concentration (1.5–6.0%), oil concentration (10–25%) and pH (5.5–7.5) regarding Turbiscan Stability Index (TSI), droplet size and zeta-potential. The validated optimised emulsion containing 4.4% protein and 17.5% oil was produced at a pH value of 6.5. This formulation had a mean droplet diameter of 6.6 ± 0.3 μm, a ζ- potential of −29.0 ± 1.7 mV and a TSI (24 h) of 0.9 ± 0.2%. This emulsion was spray-dried with and without maltodextrin (M20) at 150 and 180 °C. The highest encapsulation efficiency was 55%, achieved at 180 °C with M20, 87% higher than dry powder at the same temperature, but without M20. The water activity of powders without M20 were 58% and 14% lower (0.20 and 0.17) than powders with M20 dried at 150 and 180 °C, (0.13 and 0.15) respectively. The mean particle size was close to 50 μm. The powder without M20, dried at 150 °C, showed the highest stability against oxidation (45 °C for 4 weeks), with a peroxide index of 311 meq of peroxide per kg of oil. Powder properties were evaluated by SEM and FT-IR. Kinetically stable emulsions and particles were produced from spent brewer's yeast ingredients, which were able to act as both carrier materials and emulsifiers, providing a more noble use for an important brewing residue.

Analysis of the Physico-chemical Characteristics of Brewers Spent Grain (BSG)

Brewer’s spent grains are byproducts produced in large quantities from the brewing industry. Characterizing agro-industrial wastes is an important step to add value and increase its viability for various applications. In this experiment, the physico-chemical characteristics of Brewers Spent Grain (Total solids, volatile solids, organic carbon, total nitrogen) were analyzed. (APHA, 1999) standard was used to analyze the characteristics. The results revealed that, BSG has a total and volatile solid content of 94.95 and 90.04 %, respectively. The carbon to nitrogen ratio of brewer’s spent grain was 13.91. After pre-treatment the moisture content and ash content were found to be 5.05% and 10.96% respectively. It was shown that BSG exhibits higher variations according to barley variety, planting time and mashing process in the factories. Keyword : BSG, total solid, volatile solid, Carbon to nitrogen ratio DOI: 10.7176/JNSR/11-18-02 Publication date: September 30 th 2020

Spent brewer's yeast as a source of high added value molecules: a systematic review on its characteristics, processing and potential applications.

Development of new strategies to add-value to agro-industrial by-products are of environmental and economical importance. Innovative and low-cost sources of protein and bioactive peptides have been explored worldwide. Spent brewer's yeast (SBY) is the second most relevant by-product from the brewing industry, and despite its nutritional (about 50% protein, dry weight) and technological potential, it is still underused or needs to be disposed of. SBY cells need to be disrupted to release intracellular and cell wall proteins. This procedure has been performed using autolysis, glass bead milling, enzymatic hydrolysis and ultrasound processing. Enzymatic treatment is usually performed without prior purification and is a challenging process, which involves multiple factors, but has been successfully used as a strategy to add value to agro-industrial by-products. Scope and approach: in this review, we particularly focused on enzymatic hydrolysis as a strategy to promote SBY valorisation, illustrating the state-of-the-art processes used to produce protein extracts from this material as well as exploring fundamental concepts related to the particularities of yeast cell disruption and protein hydrolysis. Furthermore, innovative applications of value-added yeast by-products in food, biotechnological and pharmaceutical industries are presented and discussed. Key findings and conclusions: the discovery of valuable compounds found in spent yeasts as well as the development of new processing methodologies have been widening the possibilities of reuse and transformation of SBY as an ingredient and innovative matrix. Once released, yeast proteins and peptides may be applied as an innovative non-animal protein source or a functional and bioactive ingredient.

A Novel and Simpler Alkaline Hydrolysis Methodology for Extraction of Ferulic Acid from Brewer's Spent Grain and its (Partial) Purification through Adsorption in a Synthetic Resin.

This work aims to develop simpler methodologies of extracting ferulic acid (FA) from brewer’s spent grain (BSG). BSG is produced by brewing companies at high amounts all over the year and does not possess a direct application. Thus, its use as raw material for extraction of bioactive compounds has gained attention in the last years. FA has different interesting applications in cosmetics, food industry, and pharmaceutics. Several studies aim for its extraction from BSG by various methods, namely alkaline hydrolysis. In the present work, we suggest the use of autoclave to process higher amounts of BSG in a lab scale. A simplification of the regular post-hydrolysis procedures is also proposed to decrease the number of experimental steps and energy costs and to simultaneously increase the extraction yield (up to 470 mg of FA per 100 g of BSG). The adsorption of extracted FA in a synthetic resin is suggested as a partial purification method.

Spent brewer's yeast as an ingredient on the elaboration of cookies

Several studies have been conducted to find ways to use the spent yeast from brewery due to their high nutritional content (e.g., proteins, vitamins and minerals). Therefore, this study aimed to characterize the spent yeast from brewery and add it to cookies as an ingredient to valorize the waste from beer production. Spent yeast in its natural and autolysed form were characterized by physical-chemical analysis. Subsequently, formulations of cookies were developed with autolysed biomass (10% and 20%). These cookies were under physical-chemical and microbiological analysis. Finally, the cookies were submitted to the evaluation of acceptability as well. Brewer’s yeast is a potential source of protein, resulting in cookies with less carbohydrate content. The cookies without biomass has better acceptability, therefore, it is necessary to improve the formulations with spent yeast. However, it was noticed that brewer’s yeast has potential for its application in food and, its use as an ingredient on food formulations can be a way to valorize the residue from beer production.

Phenolic Acids, Antioxidant Capacity, and Estimated Glycemic Index of Cookies Added with Brewer's Spent Grain.

Brewers' spent grain (BSG) is the major by-product of the brewing industry, with great potential as a functional ingredient due to its bioactive compounds. Thus, BSG could be suitable for improving the low nutritional quality of wheat-based snacks highly consumed by young people. The objective of this study was to substitute wheat flour with BSG (0, 10, 20, and 30%) for cookies elaboration, and evaluate the dough rheology, phenolic acids, antioxidant capacity, arabinoxylans content and proximate composition of the cookies Protein content and bioactive compounds (ferulic and p-coumaric acids, water unextractable arabinoxylans) of cookies significantly (p < 0.05) increased with the substitution level. In comparison to the wheat-alone cookies, the 20% BSG-containing cookies showed a lower hydrolysis and glycemic index (GI), and less total starch. The low cost, protein-rich BSG with antioxidant capacity improves the nutritional quality of cookies and may confer health benefits beyond basic nutrition.

A Mini-Review on Brewer's Spent Grain Protein: Isolation, Physicochemical Properties, Application of Protein, and Functional Properties of Hydrolysates.

There is a growing demand in reusing agro-industrial waste to enrich food proteins and develop new protein-related products. Brewer's spent grain (BSG), the byproducts generated from the processing of beer-brewing industry, is rich in abundant protein (26 to 30%) with good physicochemical properties and nutritional benefits. BSG is mainly composed of four proteins including hordein, gluten, globulin, and albumin. The methods for extracting protein from BSG mainly include alkali extraction, ultrasonic-assisted extraction, and organic solvent extraction, among others. However, little researches have described the functional properties of Brewer's spent grain protein (BSGP) and how it can be improved by enzymatic modification. Additionally, BSG protein hydrolysates (BSGPHs) have good bioactivities, mainly including antioxidant, antiinflammatory, and angiotensin-I-converting enzyme inhibitory activities, among others. Based on the above situation, this review provides a comprehensive overview about the isolation, physicochemical features, application of the BSGP. In addition, the functional properties and biological activities of BSGPHs are also emphasized. The purpose of this review is to provide an up-to-date summary of BSGP research, and to broaden the market potential of this emerging protein in food industry. Besides, this review provides a reference to study the use of BSGP or hydrolysates for a variety of purposes in-depth, including pharmaceutical, food, and industrial applications.

Aeration challenge in high BSG suspended fermentation: Impact of stirred-tank bioreactor scale

The high loading of lignocellulosic substrates could merge the advantages of solid-state and submerged fermentations. However, high solid loading in bioreactors could result in oxygen mass transfer complications and caused extra waste of inlet air. In this work, the effects of Brewer's Spent Grain (BSG) loading on enzyme production, oxygen transfer rate (OTR) and carbon dioxide evolution rate (CER) were investigated at 50, 75 and 100 g L−1 BSG in a 2.5-L stirred tank bioreactor. However, in small-scale bioreactor, the short contact time and inadequate mixing of bubbles in liquids affected the OTR and gas holdup negatively. Therefore, xylanase production in a 14-L vessel with 100 g L−1 BSG has been studied. In a larger bioreactor, a remarkable improvement in OTR and a significant reduction in total air consumption were recorded. Furthermore, the enzyme production per 1 L of consumed air was four times greater than 2.5-L vessels. As a result, the energy consumption for aeration was less in the larger bioreactor with high solid loading. Additionally, the residual xylan content monitoring during enzyme production has revealed that the BSG's xylan content decreased in the first 12 h of cultivation and then it remained approximately constant that probably means further xylanase induction is influenced by the concentration of BSG's hydrolysis products. Concisely, it seems that initial higher solid loading could be used as a practical alternative to solid substrate feeding during the fermentation. These findings would be useful for the fermentation of high loading lignocellulosic material in the industrial-scale bioreactor.

Development of Novel Added-Value Products, Using Brewers Spent Grain as Ingredient

In recent years many studies have shown that brewers spent grain (BSG), the major by-product of the brewing industry, is no longer regarded as waste but rather as a rich source of bioactive compounds. With a hypothesis that this by-product could be efficiently valorized in developing new added-value food products this study evaluates the content of BSG in several bioactive compounds and assessed their influence on enhancing the nutritional quality of a basic snack composition. The substitution of wheat flour with 10%, 20% and 30% ground BSG led to development of three breadsticks formulations with increased nutritional value (protein, fiber, lipid and minerals) and enhanced antioxidant properties, in a dose dependent manner. Also, the sensorial analysis revealed that, compare with a control sample, the prototype with 10% and 20% BSG had good organoleptic attributes and overall acceptability. The obtained results emphasize the great opportunity to reuse this by-product in developing innovative added-value food products.

Biosourced Disposable Trays Made of Brewer's Spent Grain and Potato Starch.

Single-use plastic items made of non-biodegradable and fossil-based materials have been identified as a major environmental problem in modern society. Food packaging materials represent an important fraction of these, and replacement with biosourced, sustainable and low-cost alternatives, is a key priority. In the present work, and for the first time, trays suitable for some food packaging applications were produced by the hot-pressing of brewer’s spent grains (BSG, a low added-value byproduct of the beer industry), bound with potato starch. Expanded polystyrene (EPS) trays were used as reference, since this material has been widely used in food packaging trays. The results demonstrated that all trays produced with varying proportions of BSG and potato starch have appropriate flexural strength, with values ranging between 1.51 ± 0.32 MPa, for 80% BSG content, and 2.62 ± 0.46 MPa, for 40% BSG content, which is higher than for EPS, 0.64 ± 0.50 MPa. Regardless of BSG content, flexural strength and modulus decreased significantly after contact with water, due to starch plasticization, attaining values below EPS. Trays produced with 60% BSG, and also with the addition of chitosan and glyoxal presented the highest flexural strength, both before and after contact with water, 3.75 ± 0.52 MPa and 0.44 ± 0.11 MPa, respectively. The latter is reasonably close to the reference value obtained for EPS.

Spent brewer's yeast as a replacement for fishmeal in diets for giant freshwater prawn (Macrobrachium rosenbergii), reared in either clear water or a biofloc environment

A 90‐day feeding experiment was conducted in order to test spent brewer's yeast as a replacement for fishmeal in diets for giant freshwater prawn (Macrobrachium rosenbergii) reared in either a recirculating aquaculture system (RAS) or a biofloc system. Triplicate groups, each of 20 prawn (6.7 ± 0.03 g), were randomly assigned to 24 identical tanks. Twelve tanks were connected to the RAS, and the other 12 tanks were connected to the biofloc system which were initially supplemented with Bacillus subtilis, molasses and blood meal to achieve a C:N ratio of 20:1. Four iso‐nitrogenous (350 g/kg) and iso‐energetic (19 MJ/kg) diets where 0%, 20%, 40% and 60% of fishmeal protein was replaced by spent brewer's yeast. Neither growth nor survival was affected (p > 0.05) by increasing levels of brewer's yeast. The exception, being fish given 60% replacement with brewer's yeast, reared in biofloc, which displayed a higher (p < 0.05) growth than fish given 40% replacement, reared in clear water. The feed conversion ratio of prawn reared in the biofloc environment was lower than in the clear water. We concluded that spent brewer's yeast represents a possible 60% substitute for fishmeal in giant freshwater prawn diets, especially for prawn reared in a biofloc environment.

Natural Red Pigment Production by Monascus Purpureus in Submerged Fermentation Systems Using a Food Industry Waste: Brewer's Spent Grain.

This paper studies the production of natural red pigments by Monascus purpureus CMU001 in the submerged fermentation system using a brewery waste hydrolysate, brewer’s spent grain (BSG). The chemical, structural and elemental characterization of the BSG was performed with Van-Soest method, Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), respectively. The lignocellulosic structure of BSG was hydrolyzed with a dilute sulfuric acid solution (2% (w/v)) followed by detoxification with Ca(OH)2. Maximum red pigment production (22.25 UA500) was achieved with the following conditions: 350 rpm shake speed, 50 mL fermentation volume, initial pH of 6.5, inoculation ratio of 2% (v/v), and monosodium glutamate (MSG) as the most effective nitrogen source. Plackett–Burman design was used to assess the significance of the fermentation medium components, and MSG and ZnSO4·7H2O were found to be the significant medium variables. This study is the first study showing the compatibility of BSG hydrolysate to red pigment production by Monascus purpureus in a submerged fermentation system.

Yeast extract production using spent yeast from beer manufacture: influence of industrially applicable disruption methods on selected substance groups with biotechnological relevance

Spent brewer’s yeast is an excellent source of a variety of bioactive substances. In this study, for the first time, the focus was solely on investigating the influence of three industrially applicable cell disruption methods (cell mill, sonotrode, and autolysis) on selected substance groups relevant for physiology and process technology. A consistent spent yeast (Saccharomyces cerevisiae TUM 68) produced in a standardized industrial pilot top-fermenting process was used as a raw material. Using mechanical methods, i.e., cell mill and sonotrode, the protein content (as not hydrolyzed in free amino acids), the trehalose and the total fat content in the yeast extract were increased compared with those produced in the autolytic method. The analyzed B vitamin levels were also higher, the biologically active 5-CH3-H4folate in particular had the greatest proportion in the folate vitamer distribution of the mechanically produced yeast extracts. An increased level of non-fragmented genomic and mitochondrial DNA could also be found in the yeast extract produced via the mechanical methods. The antioxidative and reduction potential was decreased by the degradation of polyphenols and glutathione in the yeast extract following autolysis. The mineral, RNA, glycogen, glucose, fructose and ash contents did not differ significantly. Therefore, the cell mill and sonotrode offered a good alternative method to conventional autolytic procedures, especially to transfer physiologically relevant substance groups in higher concentrations to the yeast extract.

Hypocholesterolemic Effect of the Lignin-Rich Insoluble Residue of Brewer's Spent Grain in Mice Fed a High-Fat Diet.

Insoluble residue (INS) is a lignin-rich fraction of brewer's spent grain (BSG) that also contains β-glucan and arabinoxylan, the major constituents of dietary fiber. We investigated the effects of INS in diet-induced obese mice in terms of lipid metabolism and metabolic diseases. Male mice (C57bl6) were fed a high-fat diet (HFD), a HFD + 20% INS, a HFD + 20% cellulose (CEL), a HFD with a combination of 20% INS-CEL (1:1), or a control diet for 14 weeks. Insulin and glucose tolerance tests were performed after 12 weeks. Fasting plasma lipids, bile acid, and fecal bile acid were measured after 14 weeks of feeding, and tissues were collected for gene expression analysis. Body weight gain was significantly reduced with all fibers, but only INS and INS-CEL decreased fasting plasma low-density lipoprotein cholesterol and total cholesterol compared to HFD. CEL and INS-CEL significantly improved insulin resistance. Fecal bile acids were significantly increased by all fibers, but there was no change in plasma bile acid. Clostridium leptum was increased with all fibers, but universal bacterial diversity was only with INS and INS-CEL. In addition, INS significantly increased the abundance of Bacteriodes, while CEL decreased Atopobium and Lactobacillus. INS feeding significantly upregulated various genes of cholesterol and bile acid metabolism, such as Srebp2, Hmgcr, Ldlr, Cyp7a1, Pparα, Fxr, and Pxr, in the liver. INS, INS-CEL, and CEL significantly attenuated liver steatosis. Our results suggest that INS from BSG induced beneficial systemic changes in mice via gut microbiota, bile acids, and gene expression in the liver.

Antihypertensive effect of spent brewer yeast peptide

Abstract Numerous studies have investigated dietary approaches to prevent chronic lifestyle-related diseases, including hypertension. Spent brewer’s yeast is the second largest byproduct originated by the brewing industry and it deserves considerable attention because of its high nutritional value, ca. 40% of its dry mass is rich in protein which can be hydrolyzed into biologically active peptides. To upgrade this byproduct, the aim of this study was initially in vitro assessment of biological properties, e.g. ACE inhibition and antioxidant activity, and then, the in vivo effect in short-term oral antihypertensive effect of hydrolyzed yeast fractions on a well characterized model to study hypertension - Spontaneously Hypertensive Rats (SHR). Here, it was demonstrated that the fraction with molecular weight below 3 kDa containing tri and tetra- peptides with hydrophobic amino acid residues – SPQW, PWW and RYW, causes the most noticeable decrease in systolic, diastolic and mean blood pressure of SHR and shows highest antioxidant effect. These properties highlight the potential use of yeast extract as nutraceutical or functional food ingredient for the management and treatment of hypertension with antioxidant effect.

Combined Utilization of Agro-Industrial Wastewaters for Non-lignocellulosic Second-Generation Bioethanol Production

Bioethanol is one of the most important renewable fuels, and its production from biomass is a potential substitute for fossil fuels. Second-generation technologies cover a wide range of biomass resources, from agriculture to forestry and waste materials. Although lignocellulosic residues represent an attractive feedstock for ethanol production, their processing is not economical due to problems arising from the recalcitrant nature of the biomass and the need for pretreatment. The main purpose of this work was to evaluate the feasibility of the direct use of three agro-industrial wastes as low-cost feedstock for ethanol production: wastewaters of the sugar-sweetened beverage industry as carbon source, purges of fermentation tanks of the brewery industry as inoculum and corn steep water from the corn starch processing industry as nitrogen source. Fermentations were performed in batch mode under anaerobic conditions, and the concentrations of sugar, biomass and ethanol were monitored over time. The process was optimized using surface-response methodology. Spent brewer’s yeast and corn steep water supplementation at ratios of 12.4 and 8.4% v/v, respectively, were optimal for ethanol production. In these conditions, the sugar available in the soft-drink wastewater was completely depleted in less than 8 h, with an average ethanol yield of 0.45 gethanol/gsugar. The process developed could become an alternative bioprocess for production of non-lignocellulosic bioethanol.