2019 年 25 巻 2 号 p. 303-312
Kefir is an ancient beverage obtained from sugar solution fermentation of kefir grains with lactic and acetic-acid bacteria and yeasts with different probiotic properties. The aim of this work was to study the microbial composition of kefir grown in three different substrates; brown sugar, purified molasses, and high-test molasses. Antioxidant activity, angiotensin converting enzyme-inhibitory (ACE-inhibitory) activity, and antibacterial activity were also evaluated. Counts of lactic acid and acetic acid bacteria and yeasts did not change significantly in the tests; however, the microbial diversity changed depending on the media and fermentation periods used. Some of the species identified were isolated for the first time in kefir beverage (Acetobacter indonesiensis, Acetobacter tropicalis, Gluconobacter oxydans, Lactobacillus farraginis, Oenococcus kitaharae, and Pichia occidentalis). In addition, three media showed ACE-inhibitory activity, which increased after fermentation. Antioxidant and ion-chelating activities decreased after the fermentation of sugar solutions. Three fermentation solutions showed antibacterial activity against Escherichia coli, Salmonella enterica serovar Typhimurium, and Staphylococcus aureus.
