Irina Kristof, Nancy Roxana Vera, and Pedro Aredes Fernandez*
*Facultad de Bioquímica Química y Farmacia – Instituto de Biotecnología – UNT, Ayacucho 471, 4000, Argentina (pedroaredes@hotmail.com)

During cider production, malolactic fermentation (MLF) is usually carried out by Oenococcus oeni. Proteolytic activity from O. oeni during MLF releases peptides and amino acids with an important nutritional role for bacterial viability. These released peptides may also benefit human health. The objective of this study was to evaluate the proteolytic activity of three strains of O. oeni against the proteins present in apple juice and the “in vitro” antihypertensive activity of the released peptides. Pasteurized apple juice was fermented with a commercial strain of Saccharomyces cerevisiae. The fermented juice was homogenized and divided into two batches. One batch was centrifuged, filtered, and pasteurized, the other with yeast cells was reserved without pasteurization. Both fractions, with and without yeast lees, were used to perform the MLF with three different strains of O. oeni. Strains RAM10 and RAM11 were isolated from Malbec wine from Tucumán. The VP41 strain was obtained from Lallemand (commercial strain). The strains were separately inoculated at a cell concentration of 106 cfu/mL into each fraction of fermented juice. Proteolytic activity and the concentration of peptides and amino acids were determined in supernatants. The ability of supernatants to inhibit the angiotensin-converting enzyme (ECA) was evaluated by the Cushman and Cheung method. The maximum proteolytic activity of the studied strains was detected in the supernatants after 24 hours of FML, with or without lees. In general, the proteolytic activity was greater in the absence of lees and greatest in the RAM11 and VP41 supernatants. The greatest inhibitory activity on ECA was detected in supernatant without lees fermented by RAM11 and the supernatant with lees fermented by strain VP41. The supernatant of the strain RAM10 fermentation had less inhibitory activity against ECA.

Funding Support: Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)