A functional yogurt was prepared with Ligustrum robustum (Rxob.) Blume extract (LRE), while its antioxidant and hypoglycemic activities were evaluated and its action mechanism was further explored. With the cofermentation of LRE, the yogurt showed the fine quality characteristics, including pH, titratable acidity, texture, syneresis susceptibility, color, microbiological content, and chemical composition. Meanwhile, the yogurt exhibited the remarkable antioxidant capability to enhance the activities of antioxidant enzymes and reduce the malondialdehyde level in animal serums. In addition, the yogurt showed the obvious hypoglycemic activity to inhibit the decrease of glucose tolerance and the increase of postprandial hyperglycemia of diabetes mice. Furthermore, using the analysis of molecular docking, the main compounds of LRE could combine tightly with α-amylase and α-glucosidase by hydrogen bond and hydrophobic interaction, so as to change their spatial structure and inhibit their biocatalytic activity in glucose metabolism. All present results suggested that LRE showed the potential value to be used as supplement to enhance the quality and functions of yogurt in food industry. Practical Application The hypoglycemic and antioxidant activities of a functional yogurt cofermented with LRE were found and its relative action mechanism was also explored. This work provide the experimental and theoretical basis for the application of this yogurt as nutraceuticals to protect human health in food industry.
The potential uses of Ligustrum robustum (Rxob.) Blume extract as a natural antioxidant to protect the quality of different oils during storage and frying process were studied. The results showed that L. robustum extract has been shown to retard the decline in the quality of both oils based on the tests of acid value, peroxide value, p -anisidine value, color, volatile flavor, and fatty acid compositions, and the protective effect of L. robustum extract on the quality of peanut oil was better than that of palm oil. By the component analysis, L. robustum extract was found to have a total phenols content of 140.75 ± 1.52 mg/g, and ligurobustoside C was identified as the main phenolic compound. The thermogravimetric and differential scanning calorimetry results showed that L. robustum extract enhanced the oxidative stability of peanut and palm oils. In addition, Fourier transform infrared results indicated that L. robustum extract had protective effects on the C=C bond and ester bond of oil molecule. Moreover, by using electron spin resonance technique, L. robustum extract showed the ability to inhibit and scavenge alkyl-free radicals in both oils. The present results suggested that L. robustum extract may protect the quality of oils during the storage and frying process by inhibiting the oxidation of unsaturated fatty acids and might be a potential natural antioxidant in the food industry. Practical Applications The excellent antioxidant ability of Ligustrum robustum (Rxob.) Blume extract on the oxidation of different oils and its low price indicated that it could be used as a new low-cost natural antioxidant in oil processing.