By-product Of Brewing Research Articles

More than just a beer – Brewers' spent grain, spent hops, and spent yeast as potential functional fillers for polymer composites

Beer is among the most popular beverages in the world, with the production distributed uniformly between the biggest continents, so the utilization of brewing by-products is essential on a global scale. Among their potential recipients, the plastics industry offers extensive range of potential products. Herein, the presented study investigated the application of currently underutilized solid brewing by-products (brewers' spent grain, spent hops, spent yeast) as fillers for highly-filled poly(ε-caprolactone)-based composites, providing the first direct connection between spent hops or spent yeast and the polymer composites. Comprehensive by-product characterization revealed differences in chemical composition. The elemental C:O ratio, protein content, and Trolox equivalent antioxidant capacity varied from 1.40 to 1.89, 12.9 to 32.4 wt%, and 2.41 to 10.24 mg/g, respectively, which was mirrored in the composites' structure and performance. Morphological analysis pointed to the composition-driven hydrophilicity gap limiting interfacial adhesion for high shares of brewers' spent grain and spent hops, due to high hydrophilicity induced by carbohydrate content. Phytochemicals and other components of applied by-products stimulated composites' oxidative resistance, shifting oxidation onset temperature from 261 °C for matrix over 360 °C for high spent yeast shares. Simultaneously, spent yeast also provided compatibilizing effects for poly(ε-caprolactone)-based composites, reducing complex viscosity compared to other fillers and indicating its highest affinity to poly(ε-caprolactone)due to the lowest hydrophilicity gap. The presented results indicate that the proper selection of brewing by-products and adjustment of their shares creates an exciting possibility of engineering composites' structure and performance, which can be transferred to other polymers differing with hydrophilicity.

New record of reusing brewing by-product for biosynthesis of prodigiosin and its novel anti-pathogen fungi via in vitro tests and molecular docking study

New record of reusing brewing by-product for biosynthesis of prodigiosin and its novel anti-pathogen fungi via in vitro tests and molecular docking study

Fermentation of brewer's spent grain liquids to increase shelf life and give an organic acid enhanced ingredient.

Brewer's spent grain (BSG) is an abundant brewing by-product, but a short shelf life limits its use. A rotary drum press can separate BSG into a solid and a liquid fraction (BSG liquid) that contains sugars. Propionic acid producing bacteria (PAB) strains from the family Propionibacteriaceae (DSM 20270, 20272, 20274, 106790) were screened for organic acids formation from BSG liquid in three fermentation setups: A single-step fermentation, a two-step fermentation with Lactiplantibacillus plantarum (NFICC 27) followed by PAB, and a co-culture of PAB with L. plantarum. The two-step fermentation produced 9.5 g/L propionic acid and 5.4 g/L acetic acid. GC-MS analysis of the fermented BSG liquid showed a decrease in off-flavours and an increase in compounds with fruity, chocolate and caramel notes. The fermented BSG liquid also had antimicrobial activity. Fermentation of BSG liquid may therefore be a suitable means of creating a clean label food ingredient with long shelf life.

Bitter substances recovery from hot trub: A study of polymeric membranes performance in a sequential mode with fouling investigation

Crossflow membrane technologies were used to clarify and concentrate the raw extract of bitter substances from hot trub, a brewing by-product, seeking to produce an alternative route for hop products via a study performance and fouling investigation. Microfiltration was performed in concentration (MF/CO) and diafiltration (MF/DF) operation modes, feeding with extract composed of lupulone/analogs (∼6 mg/g), iso-α-acid (∼4 mg/g), and humulones/analogs (∼2 mg/g). The MF/CO had ∼69 % bitter substances permeation, while the MF/DF exhibited an increase of about 22 % in relation to MF/CO only (achieving 81–92 % the bitter substances permeation), being colupulone and n-+adlupulone presenting minor retention (<16 %). Adding the diafiltration step had not modified the profile of permeate fluxes curves, which was close to the exhibited by MF/CO. Concerning the sequential nanofiltration approach, six commercial membranes with different thin-film features and nominal molecular weight cut-offs ranging from 1000 to 150 g/mol (NP010 ≥ UA60 > NP030 > XN45 > NF9 > HL) were tested, operating with a clarified extract from MF/DF. XN45 and HL membranes presented higher bitter substance retention with less flux decay (∼42 %) than others. Membrane surfaces were altered after filtrations in relation to chemical profiles, morphology, and hydrophobicity, indicating a foulant layer formation. Different compositions and morphology of foulant layer were observed, being proteins the principal fouling agent for microfiltration while bitter substances were the main agent for nanofiltrations.

Durum Wheat Fresh Pasta Fortification with Trub, a Beer Industry By-Product.

Trub is a brewing by-product rich in proteins and fibers. We used trub, after a debittering step, at 5, 10, and 15 g/100 g (PT5, PT10, and PT15, respectively) to fortify durum wheat fresh pasta. Technological and physical–chemical properties, in vitro digestibility, and sensorial characteristics of fortified pasta were determined. The technological aspects of the products were peculiar, suggesting the existence of complex interactions between the gluten network and starch with debittered trub powder. The fortified pasta samples showed a lower glucose release than the control at the end of in vitro starch hydrolysis. Furthermore, in vitro protein digestion rose only in PT15. PT5 and PT10 samples overcame the sensory acceptability threshold of 5, while PT15 showed the lowest acceptability. Debittered trub represents a suitable ingredient in fortified fresh pasta formulation with an up to 10% substitution level without compromising the quality and sensory characteristics of the final product.

Aqueous ethanol organosolv process for the valorization of Brewer’s spent grain (BSG)

Brewers spent grain (BSG), the main solid byproduct of brewing, is annually generated by ca 37 million tons worldwide, which due to limited application, mostly ends up in landfills. This study aims to separate BSG’s fractions (lignin, cellulose, and hemicellulose) by ethanol organosolv pretreatment. Lignin-rich fractions were recovered using a two-step separation technique. The effects of temperature, retention time, and ethanol concentration on the quantity and quality of fractions were studied. The temperature considerably impacted the quality and quantity of obtained fractions, while other parameter effects greatly depended on the temperature. Substantial hemicellulose removal (90 %) along with lignin removal (56 %) and recovery (57 %) were obtained at 180 °C. The highest lignin purity (95 %) was obtained at the pretreatment conditions of 180 °C, 120 min, and 50 % ethanol concentration. This work provides an alternative route for BSG utilization, mitigating its environmental impact while enhancing the economy of a brewery.

Brewing by-product valorisation: trub debittered for nutritional and quality improvement of pasta

Trub, a brewing by-product, can be used as alternative ingredient for foods nutritional enrichment after its bitter compounds extraction. Study presents the optimisation of bitter compounds extraction from trub by Box-Behnken design, and use of debittered trub (DT) as new ingredient to enrich pasta. Bitterness extraction process was evaluated at different pH levels, time and extraction steps, and physical-chemical properties of DT (obtained under optimal conditions) were evaluated. Pasta was enriched with DT (5%, 10% and 15%) and its physical-chemical and quality properties were evaluated. Protein structure and chemical composition of trub were altered after process, also modifying its technological properties. Pasta with 10% DT increased in 33.51% protein content. Interaction of DT and wheat proteins resulted in a more compact structure, and DT water absorption capacity provided pasta texture changes. DT use improved pasta nutritional and quality properties, enabling trub valorisation and its use as vegetable proteins alternative source.

Nutritional properties of bread with the addition of brewing spent grains

Waste brewing grain, also called spent grain, is a cheap by-product of brewing, and at the same time a valuable source of dietary fiber, protein and essential amino acids, minerals, polyphenols, vitamins and lipids. Taking into account the valuable nitrionic properties of spent grain, a rational approach is to include it in bread and evaluate its contribution to the nutritional composition, profile of volatiles, and also its effect on the sensory properties of fortified bread. Replacing bread flour with 5%, 10%, 15% and 20% grain flour has resulted in bread formulations with increased nutritional value (higher fiber, protein, fat and minerals) and flavoring qualities that impart characteristic volatile compounds. Sensory analysis has shown that, compared to bread made with 100% flour, bread formulations with up to 10% grains have good organoleptic characteristics, which indicates the possibility of using this by-product as an enrichment ingredient in baked goods.

Microbial and chemical dynamics of brewers' spent grain during a low-input pre-vermicomposting treatment

The eco-sustainability of industrial processes relies on the proper exploitation of by-products and wastes. Recently, brewers' spent grain (BSG), the main by-product of brewing, was successfully recycled through vermicomposting to produce an organic soil conditioner. However, the pre-processing step there applied (oven-drying) resulted in high costs and the suppression of microbial species beneficial for soil fertility. To overcome these limitations, a low-input pre-processing step was here applied to better exploit BSG microbiota and to make BSG suitable for vermicomposting. During 51 days of pre-treatment, the bacterial and fungal communities of BSG were monitored by denaturing gradient gel electrophoresis (DGGE). Chemical (carbon, nitrogen, ammonium, nitrate content, dissolved organic carbon) and biochemical (dehydrogenase activity) parameters were also evaluated. Mature vermicompost obtained from pre-processed BSG was characterized considering its legal requirements (e.g., absence of pathogens and mycotoxins, lack of phytotoxicity on seeds), microbiota composition, and chemical properties. Results obtained showed that throughout the pre-process, the BSG microbiota was enriched in bacterial and fungal species of significant biotechnological and agronomic potential, including lactic acid bacteria (Weissella, Pediococcus), plant growth-promoting bacteria (Bacillus, Pseudomonas, Pseudoxhantomonas), and biostimulant yeasts (Pichia fermentans, Trichoderma reesei, Beauveria bassiana). Pre-processing increased the suitability of BSG for earthworms' activity to produce high-quality mature vermicompost.

Bioprocessed Brewers' Spent Grain Improves Nutritional and Antioxidant Properties of Pasta.

Brewers’ spent grain (BSG), the by-product of brewing, was subjected to a xylanase treatment followed by fermentation with Lactiplantibacillus plantarum PU1. Bioprocessed BSG has been used as ingredient to obtain a fortified semolina pasta which can be labeled as “high fiber” and “source of protein” according to the European Community Regulation No. 1924/2006. Compared to native BSG, the use of bioprocessed BSG led to higher protein digestibility and quality indices (essential amino acid index, biological value, protein efficiency ratio, nutritional index), as well as lower predicted glycemic index. Bioprocessing also improved the technological properties of fortified pasta. Indeed, brightfield and confocal laser scanning microscopy revealed the formation of a more homogeneous protein network, resulting from the degradation of the arabinoxylan structure of BSG, and the release of the components entrapped into the cellular compartments. The extensive cell wall disruption contributed to the release of phenols, and conferred enhanced antioxidant activity to the fortified pasta. The persistence of the activity was demonstrated after in vitro-mimicked digestion, evaluating the protective effects of the digested pasta towards induced oxidative stress in Caco-2 cells cultures. The fortified pasta showed a peculiar sensory profile, markedly improved by the pre-treatment, thus confirming the great potential of bioprocessed BSG as health-promoting food ingredient.

Flash hydrolysis of yeast (Saccharomyces cerevisiae) for protein recovery

Protein-rich spent yeast is a waste by-product of brewing and other fermentation industry. A continuous-flow hydrothermal treatment called ‘flash hydrolysis’ was deployed for protein recovery and yeast disposal. A feed slurry with 1–15 wt% yeast was hydrolyzed at temperatures ranging between 160 and 280 °C for a very short residence time of 10 ± 2 s. Using 10 wt% yeast at 240 °C, 66.5% carbon, 70.4% nitrogen and 61.0% overall yeast biomass was solubilized in liquid hydrolysate. The liquid hydrolysate in which 63.1% of analyzed amino acids in yeast feed were solubilized, was tested as nutrient for cultivation of E. coli in a continuous bioreactor. The steady-state E. coli concentration was 1.18 g L−1 and 0.93 g L−1 using liquid hydrolysate and commercial yeast extract, respectively. Finally, the kinetic parameters for yeast solubilization (reaction order, activation energy and pre-exponential factor) were found to be 0.86, 21.3 kJ mol−1 and 19.36 [L g−1]n−1 s−1, respectively.

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.

Mechanism of high folate accumulation in a sake yeast other than Kyokai yeasts

Folates are important vitamins in human nutrition. Pressed sake cake, a brewing by-product of sake, is a rich dietary source of folates derived from sake yeast (Saccharomyces cerevisiae). The National Research Institute of Brewing investigated 106 samples of pressed sake cake and revealed that three samples containing large amounts of folates were produced by Km67 yeast derived from the house sake yeast strain of Kiku-Masamune sake brewery. In this study, we performed sake brewing tests using Km67 and Kyokai no. 7 group strains and confirmed that Km67 yeast contributed to the production of pressed sake cake containing large amounts of folates. To elucidate the mechanisms of high folate accumulation in Km67, we performed whole-genome sequence analysis in Km67 and then screened 10 folate-metabolizing genes showing different sequences in Km67 and K7 strains. By folate analysis of each gene-disrupted strain derived from strain BY4743, we also selected four genes having significant effects on folate content in yeast from 10 candidate genes. Folate analysis of gene-disrupted yeast strains complemented with either Km67-type genes or K7-type genes revealed that the Km67-type HMT1 gene was related to high folate accumulation not only in laboratory yeast but also in sake yeast. In this gene, Leu63Phe was present in the methyltransferase motif I of Hmt1p, which was essential for the methyltransferase activity of Hmt1p. Our results and previous reports suggested that the methyltransferase activity of Km67-Hmt1p was higher than that of K7-Hmt1p, leading to enhanced production and high accumulation of folates in Km67 yeast.

Comparative analysis of vermicompost quality produced from brewers’ spent grain and cow manure by the red earthworm Eisenia fetida

Brewers’ spent grain (BSG) is a by-product of brewing that is usually used as low-value animal feed, although it can be better exploited in biotechnological processes, such as vermicomposting. Here, the chemical, biochemical and microbiological qualities of vermicomposts produced by the earthworm Eisenia fetida were evaluated using three substrates: BSG; cow manure (CM); BSG plus cow manure (1:1; BSG/CM). Over after 5 months of bioconversion by earthworms and microorganisms (thereafter vermicomposting), BSG and BSG/CM showed reduced total organic carbon, and increased total nitrogen and total humic substances like (HSl), suggesting enhanced mineralisation and stabilisation. Suitability of BSG as substrate for earthworms was confirmed by the earthworm fatty acid profile, characterised by prevalence of C:17, C18:1, C18:2 and C18:3 fatty acids. Higher fungi and yeast abundance in BSG vermicompost was accompanied by higher dehydrogenase activity. E. coli, Salmonella spp. and Ochratoxin A levels were below the legal limits.

Antioxidant properties of high molecular weight compounds from coffee roasting and brewing byproducts

Background: Coffee is one of the main sources of dietary melanoidins. Coffee melanoidins have antioxidant properties and are associated with protective effects against oxidative damage. The aim of this research was to study the potential of melanoidins obtained from coffee byproducts as functional ingredients to improve gastrointestinal health using normal human colon cells. Melanoidins were extracted from two coffee byproducts: coffee silverskin (CSE) and spent coffee grounds (SCG). Extraction was carried out by ultrafiltration using a 10 kDa molecular cut membrane. Safety of raw materials and isolated fractions was studied by microbiological analysis and determination of acrylamide, respectively. Characterization of coffee isolates was assessed by UV-Vis absorption spectroscopy, infrared spectroscopy, and determination of browning, protein content and antioxidant capacity measured by ABTS and formation of intracellular ROS in human intestinal cells (CCD18 cell line). The high molecular weight (HMW) enriched fraction showed antioxidant capacity and protected intestinal cells against induced oxidative stress. Coffee byproducts generated after the roasting process are a sustainable source of melanoidins that may act as antioxidants and therefore, may have the potential to be used as a functional novel ingredient for the prevention of gastrointestinal diseases caused by oxidative stress.Keywords: Coffee byproducts, gastrointestinal health, melanoidins, sustainable health.

Characterization of a Potential Bioactive Food Ingredient from Inner Cellular Content of Brewer’s Spent Yeast

Yeast harvesting and re-pitching is a common practice in most breweries. The reuse of four to six generations before yeast disposal is frequent. Nevertheless, Brewer’s spent yeast (BSY) is the second major brewing by-product, mostly used for animal feed. Despite its underutilization it can be a valuable source of bioactive compounds. In this work, a bioactive food ingredient was obtained from the inner cell content of BSY by mechanical disruption of yeast cell wall. Proximate composition, biological activities [proteolytic, antioxidant and angiotensin converting enzyme-inhibitory (ACE-I) activity] and amino acid profile of freeze-dried BSY extracts with different number of brewing reuses were assessed. Additionally, the stability of the biological properties during 6 months of extract storage at − 25 °C was also evaluated. Proteins were the major components of BSY extracts and yeast re-pitching increased their content. The antioxidant activities of the BSY extracts were not influenced by the serial reuse of yeast biomass in brewing, neither by extracts storage. However, BSY extracts prepared from yeast with lower number of brewing reuses presented the highest proteolytic activity and maximum ACE-I activity. BSY extracts are promising as a protein rich bioactive ingredient for food industry, presenting an amino acid profile well balanced for human consumption.

Characterization of Hop Acids in Spent Brewer's Yeast from Craft and Multinational Sources

Spent brewer's yeast, a significant byproduct of brewing, presents a disposal issue for craft breweries. To understand value-added opportunities for its use, we measured hop acid profiles of spent yeast from three beer styles produced by a craft brewery and spent yeast from three multinational breweries using high-performance liquid chromatography with photodiode array detection/mass spectrometry. The average α-acid content of craft yeast (2,074 ± 531 μg/g) was 12-fold higher than multinational brewery samples (167 ± 89 μg/g), and the average total hop acid content of craft yeast samples (2,557 ± 622 μg/g) was fivefold higher than the multinational brewery yeast samples (487 ± 136 μg/g). Centrifuged craft yeast slurry from both light and dark ales had 7-to 10-fold, 150- to 158-fold, and >200-fold higher content of iso-α-, α-, and ß-acids, respectively, than that in the corresponding beer, demonstrating a high affinity of brewer's yeast for hop acids. Ongoing research has shown that hop acids have antioxidant, anti-inflammatory, anticancer, and antibacterial activities. The elevated content found in spent craft brewer's yeast suggests consideration for use as a high-value functional food ingredient.

Physical properties of bacterial cellulose composites for wound dressings

To test various formulas and techniques for manufacturing dry-fabricated bio-film (DFBF) that exhibits physical properties advantageous to the use of the DFBF in wound dressings, a DFBF was fabricated by adding chitosan (Chi) and alginate (Alg) to homogenized bacterial cellulose (BC) obtained from vinegar pellicles in vinegar brewing byproducts in this study. The results revealed that the degree of oxidation in DFBF manufactured using hydrogen peroxide oxidized BC (HOBC), with 0.092% carboxyl group content, was lower than that in DFBF manufactured using periodic acid oxidized BC (POBC), but DFBF made using HOBC exhibited higher elongation, rehydration, swelling ratios, and water vapor transmission than that fabricated using POBC. A DFBF composite gel with 98.5% water content possessed appropriate fluidity for molding. After 10 min of rinsing cross-linked HOBC, 72 ppm of calcium remained in the final DFBF, which not only prevented cell toxicity but also demonstrated desirable mechanical and rehydration properties. Overall, the modified DFBF possessed a high rehydration ratio of 51.69% and could absorb and gradually release naringin by up to 80% within 24 h. This modified DFBF has the potential for exudate absorption and the controlled release of medicinal substances at the initial stage of healing when used in wound dressings.

Production of Aspergillus niger biomass from aqueous extract of brewer's spent grain

Suitability of brewer`s spent grain (BSG) liquor for Aspergillus niger biomass (single cell protein) production was investigated. Aspergillus niger was grown in unsupplemented and supplemented (glucose or nitrogen sources [(NH 4 ) 2 SO 4 , NaNO 3 , NH 4 Cl, NH 4 NO 3 and KNO 3 ]) BSG liquor by submerge fermentation on rotary shaker (120 rpm) at 28 o C for eight days. A. niger cell biomass was harvested daily, pasteurized, centrifuged and dried (80 o C). Glucose supplemented medium gave the highest biomass (1.64g dry wt. /L) and protein content (0.86g/L) at the 4 th day of fermentation. (NH 4 ) 2 SO 4 was the best N 2 supplement with a biomass yield of 1.43g dry wt. /L and protein content of 0.81 g /L. This study demonstrated that the production of Aspergillus niger biomass is a way of utilizing BSG (a low cost readily available by-product of brewing) to ensure a sustainable reuse of its bioresources. It also established that Aspergillus niger biomass production can be enhanced by supplementation of BSG liquor with glucose or (NH 4 ) 2 SO 4 with a maximum fermentation period of four days. Keywords : Biomass, Brewer`s spent grain, Aspergillus niger , Protein, Fermentation.

Recycling and Refining of Alcohol Derived from Waste Beer Separated from Spent Yeast

Spent yeast slush is a by-product of brewing, the yield of which is approx. 1.5% of total beer production. The yeast is separated from the spent yeast slush, which can be utilized generally, while the rest of the waste beer can be used as raw material to produce alcohol. A technique was proposed to recycle and refine alcohol from the waste beer separated from spent yeast. The rough alcohol was recycled from spent yeast after distillation by a continuous column consisting of 28 plates. The flow rate of the waste beer was 11.1 kg/min. The still pressure was 0.12 MPa, and the temperature at the top of the column was 85°C. The rough alcohol obtained was bitter and astringent and was refined using a 50-L batch column. Some parameters were optimized during the refining process of batch distillation. The initial alcohol content was 60%, and the reflux ratio was 3. The foreshot recovery was 3%, while the feints recovery was 14%. The refined alcohol was treated with 0.4% (wt/wt) activated carbon for 24 hr and then analyzed based on Chinese national standard GBT394.2–2008.