Microbiological Quality, Fatty Acid and Amino Acid Profiles of Kefir Produced from Combination of Goat and Soy Milk

Abstract

3 Abstract: The microbiological quality, fatty acid and amino acid profiles were studied in kefir prepared from combination of goat and soy milk (100:0), (50:50) and (0:100). Total counts, total of lactic acid bacteria (LAB) and total yeast of kefir were counted with Standard Plate Count (SPC). Fatty acids composition was analyzed by gas chromatography (GC), whereas amino acids composition was analyzed by high performance liquid chromatography (HPLC). The results showed that there were no significant difference in total counts, LAB and yeast of all kefir. The acidity of kefir made from soy milk only was lower (p<0.05) than kefir made from goat milk or combination of goat and soy milk, whereas there were no significant difference in pH. Caproic (C6:0), heptadecanoic (C17:0), behenic (C22:0) and pentadecanoic (C15:1) acid of kefir made from 50% goat milk and 50% soy milk mixture (50:50) were lower (p<0.05) than goat milk kefir (100:0), but the oleic acid (C18:1) of kefir made from combination of 50:50 was higher (p<0.05) than 100:0. The amino acids composition of kefir made from goat milk only (100:0) and combination 50:50 was not significantly different. Therefore, this study suggests that soy milk can substitute 50% of goat milk to produce kefir without changing the microbiological quality, acidity, pH value, amino acids profile and even increase the oleic acid.