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[Display omitted] • Utilization of brewers' spent grain (BSG), spent hops (SH) and spent yeast (SY). • BSG, SH, and SY applied as fillers for poly(ε-caprolactone) (PCL)-based composites. • The first direct connection between SH or SY and the polymer technology. • Composites' oxidative resistance enhanced by SY incorporation. • Compatibility of PCL-based composites enhanced by SY application. 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. [ABSTRACT FROM AUTHOR]

Brewing generates large amounts of residues including barley malt rootlets, spent hops, and spent yeast. These residues are sustainable and rich sources of compounds with valuable nutritional and functional properties such as proteins, polyphenols, and polysaccharides. The growing scarcity of natural resources and the increasing unsustainability of waste management, in the context of a rising global population, stress the need for reusing these wastes. This requires the development of suitable methodologies to recover interesting compounds. This work reviews the characteristics of brewery residues, the methodologies employed for the recovery of their valuable compounds, their functionalities, and their potential applications. A special consideration was focused to those methods employing innovative and sustainable approaches such as the use of deep eutectic solvents, microwave-assisted extraction, pulsed electric fields, high intensity focused ultrasounds, pressurized liquids, and supercritical fluids. Key findings and conclusions : Despite the general use of conventional solid-liquid extraction, works using emerging techniques are becoming more usual. While the benefits of these techniques in relation to sustainability are clear, yields are not always as high as expected. Polyphenols and proteins were mostly extracted from barley malt rootlets, while spent hops are more appreciated for their polyphenols, especially xantohumol and essential oils, and spent yeast is rich in polysaccharides, especially β-glucan, proteins, fatty acids, and flavour enhancers nucleotides. Some of these compounds exert significant antioxidant, antiproliferative, and immunoactivity and are potentially interesting for the food, cosmetic or pharmaceutical industries. [Display omitted] • Malt rootlets, spent hops, and spent yeast from brewery are sources of valuable compounds. • They have been mainly recovered by conventional solid-liquid extraction. • Great efforts are recently performed to use emergent and more sustainable techniques. • Some compounds show antioxidant, antiproliferative, antiinflammatoty or immune activity. • β-glucan, proteins, polyphenols, and nucleotides show potential industrial applicability. [ABSTRACT FROM AUTHOR]

[Display omitted] • Xanthohumol has several pharmacological properties of interest for human health. • Female inflorescences of Humulus lupulus (Hops) are the natural source of xanthohumol. • Emerging technologies have been investigated to increase xanthohumol extraction yield. • Hot trub and spent hops, by-products from beer brewing, can be sources of xanthohumol. Xanthohumol, a chalcone unique to hops, has attracted attention from researchers due to its several pharmacological effects on humans. In industry, hops are almost exclusively used in beer production, generating tons of solid waste – hot trub from the boiling step and spent hops from the dry hopping – rich in biocompounds, among them xanthohumol, that could be recovered and used for several nutritional purposes. The literature is extensive on extraction processes of xanthohumol directly from hops, but only a few studies present its recovery from brewery solid waste. We focus on presenting the xanthohumol characteristics and benefits for human consumption, and discuss the main extraction techniques, their advantages and limitations, to prospect strategies to recover this high-value compound from brewing solid waste. Recent extraction processes represent promising approaches to overcome the limitations of conventional methods, but further studies are still needed to understand xanthohumol extraction and purification and induce industrial upscaling. [ABSTRACT FROM AUTHOR]

Spent hop extract (SHE) is hypothesized to possess multifaceted anticoagulant effect and to reduce platelet reactivity in a direct manner and to improve the antiplatelet action of endothelium. The results demonstrated that SHE, rich in flavanols (50% of total phenolic compounds), hydroxycinnamic acids, proanthocyanidin oligomers, flavan-3-ol monomers, and flavonol glycosides, inhibited ADP-induced platelet aggregation up to 11% for 7.5 µg/ml or up to 23% for 15 µg/ml, P  <   0.05. Additionally, SHE ameliorated anticoagulant activity of human endothelial cells to significantly reduce platelet reactivity. This effect could be related to the increased expression/activity of the ecto-ADPase (CD39). ADP-induced platelet reactivity was reduced in the case of platelets incubated with the extract-treated endothelial cells compared to the untreated cells. Diabetic rats fed with SHE demonstrated longer survival time than the group treated with placebo. In conclusion, our study provided evidence for a potential beneficial role of SHE in the regulation of platelet and endothelial function. [ABSTRACT FROM AUTHOR]

Abstract: The biotransformation of xanthohumol (1), a prenylated chalcone isolated from hops by selected fungi, was investigated. Microbial regioselective glycosylation at the C-4′ position led to xanthohumol 4′-O-β-d-glucopyranoside (2) and xanthohumol 4′-O-β-d-(4′′′-O-methyl)-glucopyranoside (3). The subsequent cyclization of 2 resulted in isoxanthohumol 7-O-β-glucopyranoside (4). The structures of the products were identified based on spectroscopic methods. The biological activity of isolated metabolites has been evaluated. Compared to xanthohumol (1), metabolite 2 is a better 2,2′-diphenyl-1-picrylhydrazyl (DPPH) radical scavenger, while 2 and 3 have stronger antiproliferative activity against the human HT-29 colon cancer cell line. [Copyright &y& Elsevier]

Abstract: The effect of enzymatic pretreatment of sugar beet pulp and spent hops prior to methane fermentation was determined in this study. These industrial residues were subjected to enzymatic digestion before anaerobic fermentation because of high fiber content (of 85.1% dry matter (DM) and 57.7% DM in sugar beet pulp and spent hops, respectively). Their 24h hydrolysis with a mix of enzymatic preparations Celustar XL and Agropect pomace (3:1, v/v), with endoglucanase, xylanase and pectinase activities, was most effective. Reducing sugars concentrations in hydrolysates of sugar beet pulp and spent hops were by 88.9% and 59.4% higher compared to undigested materials. The highest yield of biogas was obtained from the enzymatic hydrolysate of sugar beet pulp (183.39mL/d from 1g COD at fermenter loading with organic matter of 5.43g COD/L×d). Fermentation of sugar beet pulp gave 19% less biogas. Methane fermentation of spent hops hydrolysate yielded 121.47mL/d biogas from 1g COD (at 6.02g COD/L×d, 13% more than from spent hops). These results provide evidence that suitable enzymatic pretreatment of lignocellulosic wastes improve biogas yield from anaerobic fermentation. [Copyright &y& Elsevier]

Abstract: The research on degradation of hop bitter acids by Candida parapsilosis culture under various conditions is described. The effects of temperature and age of precultures were investigated. Supernatant of the precultures, growing cells and resting cells of the cultures were used for the tests. The highest levels of degradation were obtained in experiments performed in the light, at 40°C, using a 3-day-old preculture of the yeast. Efficiency of the degradation was determined by concentration of riboflavin in the C. parapsilosis culture. Commercial hop extract and spent hops were used in the experiments. [Copyright &y& Elsevier]

Hop pectins were extracted from spent hops using acid extraction conditions and were characterized chemically. The acid extraction of spent hops resulted in a yield of 2%, containing 59% of polysaccharides. The hop pectins under investigation had a relatively high molecular weight and an intrinsic viscosity comparable to that of commercially available apple and citrus pectins. The low degree of methyl esterification of these pectins implicates that they are mainly suitable for use in calcium gels. The degree of acetylation and the neutral sugar content were relatively high.A high molecular weight fraction which contained arabinogalactan-proteins was shown to be present in the hop pectin extract after preparative size-exclusion chromatography. Additionally, a fraction with a lower molecular weight was present containing mainly homogalacturonans. The arabinogalactans in the high molecular weight population consisted of (1→3)- and (1→3,6)-linked galactans highly branched with arabinose and galactose side-chains. The protein part of the arabinogalactan-protein (13%) was found to be rich in cystein, threonin, serinin, alanin, and hydroxyprolin. The molecular weight distribution of the hop pectin after degradation with the enzymes endopolygalacturonase plus pectin methyl esterase suggested that the arabinogalactan-protein present in the hop pectin extract was linked to the pectin and that the arabinogalactan-protein itself had a fairly low molecular weight. [Copyright &y& Elsevier]

• The use of choline chloride-based DESs allows extraction of xanthohumol from spent hops. • Xanthohumol–rich precipitates are obtained by adding water (antisolvent) to the DES extract. • The highest xanthohumol extraction yield was obtained using a DES composed of choline chloride and propylene glycol. • Optimization of the extraction conditions improved the xanthohumol extraction efficiency 3-fold. • DES could be recovered and reused at least three times without compromising the xanthohumol extraction yield. Spent hops (SH) are a rich source of the prenylated chalcone, xanthohumol (XN), which has a broad spectrum of biological activity. In this study, four choline chloride-based deep eutectic solvents (DESs), which contained glycerol, ethylene glycol, propylene glycol, or lactic acid as a hydrogen bond donor, were tested for the extraction of XN from SH. XN-rich precipitates were obtained by the addition of water (as an antisolvent) to the DES extracts. To determine the XN contents, the precipitates were extracted with methanol and then analyzed by HPLC. The highest XN extraction yield (2.30 mg/g SH) was obtained using a DES composed of choline chloride and propylene glycol (1:2 mol/mol) with 5 wt% water, 1:50 SH/DES (w/w), and 3:1 antisolvent/DES (v/w) at 60 °C for 1 h. This DES could be recovered and reused at least three times without significantly decreasing the XN extraction yield. Our results therefore demonstrated that DESs can be considered green, efficient, and promising solvents for the extraction of XN from SH. Moreover, the proposed simple DES-based method appears to be an effective alternative to conventional XN extraction methods. [ABSTRACT FROM AUTHOR]