CHANGES IN ENZYMATIC ACTIVITIES, BIOCHEMICAL PROPERTIES AND ANTIOXIDANT ACTIVITY DURING KINEMA FERMENTATION

Abstract

Kinema, a soybean fermented food is traditionally consumed by the Limbu and Rai, Nepalese inhabiting Nepal, India, some parts of Bhutan and Manmyar. This study was carried out with an aim to determine the changes in enzymatic activity, biochemical parameter and antioxidant activity during the 3 days kinema fermentation. For the kinema preparation, brown soybeans were cleaned, washed and soaked in water overnight at ambient temperature. During the fermentation process, the samples of every 12 h difference was collected for 3 days which was then taken for the study. Analytical procedures were done where enzymatic activity (Protease and amylase), physicochemical changes (Reducing sugar, Trichloro acetic acid soluble Nitrogen, protein, total phenolic content) and antioxidant activity were determined and compared between the samples. Similarly, pH values were also observed during each 12 hour fermentation time. The data were analyzed by using one way ANOVA using Genstat at 5% level of significance level. The highest protease activity was found to be 0.190 ± 0.001 U/ml at 60 h of kinema fermentation which initially showed negative activity at 0 h (-0.008 U/ml). The pH value increased from 6.8 to 8.5 from 0 h to 72hrs of fermentation. Similarly, protein content was increased on the progressive interval of fermentation time with highest value of 2.758 ± 0.097 mg/ml at 72hrs of fermentation. Furthermore, Trichloro acetic acid soluble Nitrogen showed increasing trend till it reached 60 h of fermentation time with 101.382 ± 1.786 µg tyrosine equivalent/ml. Bioactive constituents like Antioxidant activity and Total phenolic activity was observed highest at 60h and 72h respectively. The higher level of the activity in kinema could be attributed to the extensive hydrolysis of proteins and an increase in the content of phytosterols. The study indicated that the Protease activity, protein, Trichloro acetic acid soluble Nitrogen along with release of bioactive constituents were higher during the third day of fermentation, while the amylase activity and the value of reduction sugar inclined during the first day of fermentation.