Goat milk Kefir with ACE inhibitory activity: Preparation and storage stability evaluation

In this study, the Box–Behnken response surface method was used to optimize the conditions of Kefir grain fermented goat milk, and the angiotensin-converting enzyme (ACE, EC 3.4.15.1) inhibitory activity and sensory evaluation were improved. The results showed that the optimum fermentation conditions were 23 hr fermentation at 24°C, and the inoculum size was 2.5%. Under optimal conditions, the ACE inhibition rate increased significantly from 73.34 ± 0.37% to 85.97 ± 0.62% (p < .05), and the sensory evaluation increased significantly from 75.83 ± 0.46 to 84.65 ± 0.76 (p < .05), close to the predicted values of 86.54% and 85.20%. The storage stability of Kefir goat milk was studied. The results showed that there was a post-acidification process during the 14-day preservation of Kefir goat milk, with the acidity increasing, the pH value decreasing, and the sensory evaluation value increasing. This study can provide a good reference for the preparation and storage of goat milk Kefir. Practical applications In recent years, Kefir's health function has been found by more and more researchers, so it has gained the favor of the majority of consumers. In this study, response surface method was used to optimize the technological parameters of Kefir grain fermented goat milk and to explore the stability of Kefir milk during storage. The storage stability of Kefir is better.