Abstract

Introduction. Brewery mash, or brewer’s spent grain (BSG), is a by-product of brewing industry. It is known to contain valuable biologically active substances. However, their extraction is complicated by the presence of various polymers. The research featured various physicochemical methods for obtaining valuable biological compounds from brewery waste. The new method modified complex non-starch polysaccharides, lignin, arabinoxylans, and other high-molecular compounds associated with phenolic compounds. The research objective was to solve the problem of recycling industrial by-products that accumulate in large quantities and require expensive processing or disposal. The paper introduces new technological approaches for deep processing of BSG as a source of secondary raw materials in order to obtain extracts fortified with polyphenolic compounds. Study objects and methods. The research featured BSG from malt subjected to treatment with ECA-activated water (catholyte with pH 9.6 ± 0.1), followed by enzymatic hydrolysis of cellulolytic enzyme preparations and extraction with a polar solvent of the resulting free polyphenolic substances. The experiments were based on standard methods for assessing the content of various biologically active substances. Results and discussion. A 70% water-ethanol solution proved to be optimal at the BSG:extractant ratio of 2:1, process temperature = 50 ± 2°C, and extraction time = 60 ± 5 min. Under the same conditions, 70 %vol. of beer distillate made it possible to extract phenolic acids, flavonoid rutin, irreplaceable and nonessential amino acids, and non-starch polysaccharide β-glucan from the BSG matrix. The BSG treatment with 1M NaOH solution delivered viscous hydrolysates fortified with flavonoids rutin and quercetin, which did not happen when acid hydrolysis was used. The combined use of ECA-treated water (catholyte with pH 9.6 ± 0.1) for 24 ± 0.05 h, combined with biocatalysis with the enzyme preparation Viskoflo MG for 2 ± 0.05 h, made it possible to obtain BSG extracts with a high content of phenolic acids and aldehydes, as well as flavonoid rutin. Conclusion. The study revealed the mechanism of hydrolytic decomposition of BSG non-starch polysaccharides, considering the compounds contained in the extracts. The BSG hydrolysates fortified with various phenolic compounds can be used in various food technologies, e.g., in fermented drinks.

Keywords

Beer, grain, ECA-water, biocatalysis, extraction, phenolic compounds

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