Acidification rate, carbohydrate metabolism and enzyme active peptide production in rice bran medium by newly lactic acid bacteria

Abstract

Rice bran contains various nutrients such as protein, fat, carbohydrate, minerals, and vitamins, making it a very useful food source. Whole rice grains can also be modified to improve their nutritional value or to promote their functional properties. For centuries fermentation with lactic acid microorganisms has been a simple and inexpensive method to improve the functional and nutritional value of foods. The aim of this study was to characterize the lactic acid bacteria previously isolated from a different spontaneously fermented cereal based media. Lactobacilli such as L. plantarum, L. brevis, L. paracasei, L. uvarum and Pediococci such as P. acidilctici and P. pentosaceus, were characterized by their growth and acidification rate, carbohydrate metabolism, and xylanase and protease activity production during fermentation of rice bran. The rice bran fermentations were carried out in a single step without growth supplementation at solid state (SSF) conditions. The P. acidilactici and P. pentosaceus showed very good properties of acidification, the pH in fermentation medium ranged from 3.92 to 3.16. Among the tested strains, the L. plantarum and L. brevis and P. acidilactici and P. pentosaceus strains were able to ferment L-arabinose and D-xylose, also hexoses D-galactose, D-glucose, and N-acetylglucosamine. All tested strains differed in the L- and D- lactic acid production rate.