Kefir properties prepared with goat milk and black rice (Oryza sativa L.) Extract and its influence on the improvement of pancreatic β-cells in diabetic rats

Abstract

This study were to evaluate the properties of kefir prepared with a combination of goat milk and black rice extract and its influence on the improvement of β-cells in streptozotocin-nicotinamide (STZ-NA) -induced diabetic rats. Kefir was divided into four groups using the following materials: goat milk (GM), goat milk+inulin (GM+IN), goat milk+black rice extract (1:1)(GM+BRE), and goat milk+black rice extract+ inulin (GM+BRE+IN). After fermentation, all kefir were stored at 4°C for 1 and 7 d, and then were analyzed for microbial, chemical properties and antioxidant activity. Furthermore, three kinds doses of kefir combination from goat milk and black rice extract (GM+BRE) were administered to rats. Thirty male rats 8-12 weeks old were divided into 6 groups: 1) negative control (normal rats); 2) positive control (untreated diabetic rats); 3) diabetic rats fed kefir (1.0 ml); 4) diabetic rats fed kefir (2.0 ml); 5) diabetic rats fed kefir (4.0 ml), and 6) diabetic rats received glibenclamide. After 28 d experiment, the rats were sacrificed for sampling pancreatic tissues. Subtitution of goat milk with black rice extract in kefir fermentation could decrease their pH and increase in radical-scavenging activity. Inulin addition able to increase (p<0.05) in radical-scavenging activity of kefir. Alcohol and total phenolic contents of kefir increased (p<0.05) after 7 d of storage, while the pH decreased. To improve insulin-producing pancreatic β-cells in diabetic rats, it was required at least 2.0 ml dose of kefir combination from goat milk and black rice extract to achieve similar effect to glibenclamide as antidiabetic agent.