The brewing sector is a significant part of the global food industry. Breweries produce large quantities of wastes, including wastewater and brewer’s spent grains. Currently, upcycling of food industry by-products is one of the principles of the circular economy. The aim of this review is to present possible ways to utilize common solid by-product from the brewing sector. Brewer’s spent grains (BSG) is a good material for sorption and processing into activated carbon. Another way to utilize spent grains is to use them as a fuel in raw form, after hydrothermal carbonization or as a feedstock for anaerobic digestion. The mentioned by-products may also be utilized in animal and human nutrition. Moreover, BSG is a waste rich in various substances that may be extracted for further utilization. It is likely that, in upcoming years, brewer’s spent grains will not be considered as a by-product, but as a desirable raw material for various branches of industry.

To make a beer there are four essential ingredients needed: water, malt, hops, and yeast. After brewing process, the main wastes are spent grains. These are often used as additions to fodders in animal husbandry. This study presents preliminary results of an investigation aiming to determine the feasibility of an alternative use of spent grains as a potential source of solid fuel. This source of energy could make breweries partly sustainable in terms of their energy supply. Such an approach may be feasible especially in large scale industrial breweries. This preliminary study presents encouraging results, showing improvements in terms of the fuel properties of the spent grain after its valorization through hydrothermal carbonization. Moreover, qualitative GC-MS analysis also indicates potential feasibility of the liquid byproduct of the hydrothermal carbonization of spent grain for biogas production. Results of proximate, ultimate, and DTG analyses show that hydrothermal carbonization of spent grain could improve its fuel properties and make it an especially suitable feedstock for fast pyrolysis and gasification. Improvement of HHV is also an improvement in terms of combustion.

A series of hydrazide-hydrazones 1–3, the imine derivatives of hydrazides and aldehydes bearing benzene rings, were screened as inhibitors of laccase from Trametes versicolor. Laccase is a copper-containing enzyme which inhibition might prevent or reduce the activity of the plant pathogens that produce it in various biochemical processes. The kinetic and molecular modeling studies were performed and for selected compounds, the docking results were discussed. Seven 4-hydroxybenzhydrazide (4-HBAH) derivatives exhibited micromolar activity Ki = 24–674 µM with the predicted and desirable competitive type of inhibition. The structure–activity relationship (SAR) analysis revealed that a slim salicylic aldehyde framework had a pivotal role in stabilization of the molecules near the substrate docking site. Furthermore, the presence of phenyl and bulky tert-butyl substituents in position 3 in salicylic aldehyde fragment favored strong interaction with the substrate-binding pocket in laccase. Both 3- and 4-HBAH derivatives containing larger 3-tert-butyl-5-methyl- or 3,5-di-tert-butyl-2-hydroxy-benzylidene unit, did not bind to the active site of laccase and, interestingly, acted as non-competitive (Ki = 32.0 µM) or uncompetitive (Ki = 17.9 µM) inhibitors, respectively. From the easily available laccase inhibitors only sodium azide, harmful to environment and non-specific, was over 6 times more active than the above compounds.

Steady consumption of beer results in a steady output of residues, i.e., brewer's spent grain (BSG). Its valorization, using hydrothermal carbonization (HTC) seems sensible. However, a significant knowledge gap regarding the variability of this residue and its influence on the valorization process and its potential use in biorefineries exists. This study attempted to fill this gap by characterization of BSG in conjunction with the main product (beer), taking into accounts details of the brewing process. Moreover, different methods to assess the performance of HTC were investigated. Overall, the differences in terms of the fuel properties of both types of spent grain were much less stark, in comparison to the differences between the respective beers. The use of HTC as a pretreatment of BSG for subsequent use as a biorefinery feedstock can be considered beneficial. HTC was helpful in uniformization and improvement of the fuel properties. A significant decrease in the oxygen content and O/C ratio and improved grindability was achieved. The Weber method proved to be feasible for HTC productivity assessment for commercial installations, giving satisfactory results for most of the cases, contrary to traditional ash tracer method, which resulted in significant overestimations of the mass yield.However, for craft breweries located in big cities, disposal becomes more problematic [3]. There are also attempts to enrich food products with spent grains. Thus far, there have been trials with sausages [4] and bread [5]. However, consumers reported that such products represent a fiber aftertaste [6]. However, this is limited only to the relatively close vicinity of a brewery, due to relatively high moisture content, that could range between 70% up to 78% 70% [7][8][9]. Biological activity of these residues makes long term storage difficult. The literature reports ongoing work on various new ways of using BSG, including extraction of polyphenols [10,11], other anti-oxidants [12,13], functional cardioprotective lipids for pharmaceutic use [14], proteins [15], fodder for edible insects [16], material for disposable trays [17], natural rubber modifier [18], as well as feedstock for production of pigments [19] and biochar, for subsequent use as soil amendment [20] or sustainable material for electrodes [21].The potential use of this residue as a fuel has been suggested by several authors so far [7][8][9]22,23]. The relatively high initial moisture content of spent grain makes hydrothermal valorization techniques the most sensible choice [8,9]. Hydrothermal carbonization (HTC), also known as wet torrefaction, is a valorization process suitable for a range of low-quality solid biomass, especially with high initial moisture content [24,25]. Process temperature, reported in the literature, usually ranges between 180 • C and 260 • C [25][26][27][28][29][30]. As the process takes place in subcritical water, pressure has to be higher than saturation pressure of water for specific temperature [25][26][27][28][29][30]. In these conditions wa...

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Physical, enzymatic and chemical methods were used to develop an efficient procedure for preparing gelatine hydrogels of appropriate strength and elastic properties for applications as enzyme carriers. The concentrations of the crosslinking enzyme (transglutaminase), the initial amount of gelatine, the production time and the effect of additional crosslinking with glutaraldehyde were examined. As a result, the following conditions were selected: 0.1 g cm

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