doi: 10.17113/ftb.55.02.17.4378

Brewery Waste Reuse for Protease Production by Lactic Acid Fermentation

Thiago Rocha dos Santos Mathias¹*, Paula Fernandes de Aguiar², Joao Batista de Almeida e Silva³, Pedro Paulo Moretzsohn de Mello⁴ and Eliana Flávia Camporese Sérvulo⁵

¹Laboratory of Fermentation Technology, Federal Institute of Education, Science and Technology of Rio de Janeiro, Senador Furtado Street 121, BR-20270-021 Rio de Janeiro, RJ, Brazil
²Institute of Chemistry, Federal University of Rio de Janeiro, Athos da Silveira Ramos 149, BR-21941-909 Rio de Janeiro, RJ, Brazil
³Pilot Plant of Beverages, Department of Biotechnology, Engineering School of Lorena, University of Sao Paulo, BR-12602-810 Lorena, Sao Paulo, Brazil
⁴Technology Center of Food and Beverage – SENAI, Nilo Peçanha Street 85, BR-27700-000 Vassouras, RJ, Brazil
⁵Laboratory of Industrial Microbiology, Department of Biochemical Engineering, School of Chemistry, Federal University of Rio de Janeiro, Athos da Silveira Ramos 149, BR-21941-909 Rio de Janeiro, RJ, Brazil

Article history:
Received July 29, 2015
Accepted December 9, 2016

Key words:
brewery waste, waste reuse, lactic fermentation, proteolytic enzymes

Summary:
This 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.

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