Influence of adjunct cultures on angiotensin-converting enzyme (ACE)-inhibitory activity, organic acid content and peptide profile of kefir

The angiotensin-converting enzyme (ACE)-inhibitory activities, peptide profiles and organic acid contents in kefir produced by kefir grains plus lactic acid bacteria as adjunct cultures were determined. All the kefir samples showed almost similar peptide profiles as detected by RP-HPLC, but quantitative differences were observed during storage. The ACE-inhibitory activities of different lactic cultures did not exhibit a linear tendency during storage period. After 7days of storage, there was a significant increase in ACE-inhibitory activity of the sample fermented with Lactobacillus helveticus. However, a kefir sample containing Streptococcus thermophilus, Lactobacillus acidophilus and Bifidobacterium animalis subsp. lactis exhibited a higher ACE-inhibitory activity (92.23%) compared to the other samples.