Brewery Wastes Reuse for Protease Production by Lactic Acid Bacteria Fermentation

Abstract

SummaryThis study evaluated the use of three solid brewery wastes: brewer's spent grain, hot trub and residual brewer's yeast, as alternative media for the cultivation of lactic acid bacteria to evaluate their potential for proteolytic enzyme production. Initially, a mixture experimental design was used to evaluate the effect of each residue, as well as different mixtures (with the protein content set at 4 %) in the enzyme production. At predetermined intervals, the solid and liquid fractions were separated and the extracellular proteolytic activity was determined. After selecting the best experimental conditions, a second experiment, factorial experimental design, was developed in order to evaluate the protein content in the media (1 to 7 %) and the addition of fermentable sugar (glucose, 1 to 7 %). Among the wastes, residual yeast showed the highest potential for the production of extracellular enzymes, generating a proteolytic extract with 2.6 U/mL in 3 h. However, due to the low content of the fermentable sugars in the medium, the addition of glucose also had a positive effect, increasing the proteolytic activity to 4.9 U/mL. The best experimental conditions of each experimental design were reproduced for comparison, and the enzyme content was separated by ethanol precipitation. The best medium produced a precipitated protein with proteolytic activity of 145.5 U/g.

Influence of Mashing Profile Curve and Addition of Proteases on the Composition of the Wort and Beer

“…The following raw materials, additives and fermentation agents were used to obtain worts and beers: water filtered on activated charcoal, Pilsen malt (Agromalte®), hops (Hallertau Perle, HGV®, 9.7% α-acids), proteolytic extract of microbial origin, obtained in previous work (Mathias et al, 2017) and bottom fermenting yeastSaccharomyces cerevisiae (W-34/70, Fermentis®).…”

“…The profile of the mash curve has a great influence on the composition of the wort and beer, affecting the nitrogen content and the type of nitrogen compounds present, with effect on several characteristics of the drink, such as the flavor (products and byproducts of the fermentation and permanence of nonhydrolyzed insoluble substances); the color (mainly by the release of soluble nitrogen and reducing sugars that will undergo subsequent parallel reactions); the texture (by the presence of proteins and dextrins); foam stability and beer turbidity (also influenced by the protein profile present); caloric power; the alcohol content; and the beverage carbonation. [4][5][6] The reduction of mashing time usually promotes problems for the wort and beer, and it is common supplementing the wort with the addition of exogenous enzymes to avoid it. Mainly microbial amylase and proteases are added to improve the hydrolytic process.…”

Utilization of brewery wastes in food industry

“…This by-product contains many valuable and bioactive substances that are important for human nutrition ( Ferreira et al., 2010 ). The use of this residue is limited by its strong bitter taste resulting from the presence of hops in boiled wort, although there are methods for removal of the taste ( Mathias et al., 2017 ). Given its high mineral content, BSY can bring beneficial effects in other branches of the food industry, including confectionery, dairy industry, and production of beverages, such as juices and mead.…”

Jamaican Domestic Ethanol Fuel Feasibility and Benefits Analysis

“…The dried yeast is sold to the pet food industry, where it is used as a nutritional supplement and flavor enhancer (Sims 2007). Between 1.5 and 3 kg of spent yeast are generated for every 100 liters of beer produced (Mathias et al 2017). There are two breweries in Jamaica: the major one is Desnoes and Geddes Ltd. (best known for its Red Stripe and Dragon brands of beer) and Razz Brewery (a small-scale local producer), both located in Kingston (Leonard 2018).…”