Isolation, Identification, and Biochemical Characterization of Lactic Acid Bacteria from Okara

Abstract

During the process of making soymilk, soybean pulp (okara) is produced as a solid waste product. However, this waste product is rich in nutrient contents such as essential fatty acids, proteins, carbohydrates, vitamins, and minerals. Hence okara is favorable for the growth of microorganisms such as lactic acid bacteria (LAB). The purpose of this study was to isolate, identify and characterize LAB from fermented okara. Isolation of LAB was carried out on MRS agar media supplemented with CaCO_3. LAB was selectively screened based on their morphological, biochemical, and physiological characterizations. A total of 133 different colonies were selected from fermented okara, of which 20 colonies were confirmed as LAB. The entire LAB isolates were catalase negative, indicating that all the identified isolates did not produce the enzyme catalase. Out of 20 LAB, 14 isolates were whitish and six isolates were found to be creamy in colony appearance. The entire LAB isolates were circular in colony shape and found to be rod in cell shape. Based on the cell shape of LAB; isolates were belongs to the genera Lactobacillus. Out of 20 isolates; SL-3, SL-7, SL-10, SL-14, and SL-19 were hetero-fermentative; and the remaining fifteen (15) isolates were found to be homo fermentative. Further studies on the properties of LAB isolate was conducted through a growth test at different temperature (15⁰C, 37⁰C, and 45⁰C) and in different NaCl concentrations. The result of the present study will contribute to the future applications and utilization of LAB as starter cultures for the production of soybean yoghurt and its use in food preservation.

Keywords: Lactic acid bacteria, Soybean, Okara

DOI: 10.7176/FSQM/117-03

Publication date:July 31^st 2022