Antioxidant Activity of Goat Milk Kefir Using Bioautography Method

Abstract

Antioxidants are compounds that can prevent and improve degenerative diseases caused by free radicals. One source of antioxidants that can be used to ward off free radicals is goat milk kefir. Goat milk kefir is a fermented milk product made by fermenting lactose in milk by the bacteria, Lactobacillus and Saccharomyces naturally found in kefir grains. This study aims to determine the antioxidant activity of goat milk kefir by biotographic analysis combined with densitometry. Testing the antioxidant activity of goat milk kefir using a positive control of water (p1), kefir 1ppm (p2); kefir 3ppm (p3); kefir 5ppm (p4); kefir 7ppm (p5); kefir 9ppm (p6); and a positive control for gallic acid (p7). The results of qualitative data analysis showed a change in purple color to yellow, while the results of quantitative data were in the form of AUC values ​​to determine the optimal % inhibition of antioxidant activity. The data were analyzed using SPSS statistical analysis with a 95% confidence level (p=0.05).The result of the study showed that goat's milk kefir has antioxidant activity. The result of qualitative data with biotographic analysis showed antioxidant activity which was indicated by a yellow color change of p2-p6 was the same as p7 of positive control for gallic acid. Meanwhile, quantitative data using densitometry analysis showed there was antioxidant activity of p2(7,4±24,8); p3 (16.6±46.9); p4 (12.7±55.5); p5(8.5±66.9);p6(14.3±69,9); and p7 (11.3±67,1). Based on statistical analysis using One Way Annova method, it showed antioxidant activity in all treatments. There was no significant difference between the concentrations of 3 ppm and 5 ppm, while the concentrations of 1 ppm, 7 ppm and 9 ppm had significant differences