山药山楂酸奶的贮藏品质及胃肠液环境下的抗氧化性

以山药、山楂及鲜牛乳为原料研制山药山楂酸奶，通过测定其低温（4 ℃）贮藏期间（1 d、7 d、14 d、21 d）乳酸菌活菌数、滴定酸度、黏度、持水性、色差等指标，分析山药山楂酸奶贮藏期间品质的变化；同时测定山药山楂酸奶在胃、肠液的模拟环境条件下对DPPH、ABTS自由基的清除能力。结果表明，低温（4 ℃）贮藏期间的山药山楂酸奶在活菌数、酸度以及抗氧化能力方面均优于对照酸奶，持水力低于对照酸奶。在低温（4 ℃）贮藏1 d时，山药山楂酸奶的DPPH和ABTS自由基清除率分别为94.57%、83.11%，对照酸奶为72.27%、72.87%。低温（4 ℃）贮藏期间，冷藏时间延长以及经过胃肠液环境下均会导致两种酸奶自由基清除率的下降，但山药山楂酸奶在总体上仍然优于对照酸奶。

Storage quality of yam and hawthorn yogurt and its antioxidation in simulated gastrointestinal fluid

Using yam, hawthorn and fresh milk as raw materials, the yam and hawthorn yogurt was developed. In order to analyze the quality changes of yam and hawthorn yogurt during its storage period, the number of viable lactic acid bacteria, titer acidity, viscosity, water holding capacity, color difference and other indicators were measured in the storage period (4 ℃) of 1 d, 7 d, 14 d, 21 d. The scavenging ability of yam and hawthorn yogurt on DPPH and ABTS free radicals under the simulated environmental conditions of gastric and intestinal juice was determined. The results showed that the yam and hawthorn yogurt during storage period (4 ℃) was better than the control yogurt in terms of viable counts, acidity and antioxidant capacity, and its water holding capacity was lower than that of the control yogurt. When stored at 4 ℃ for 1 d, the free radical scavenging rates of DPPH and ABTS of yam and hawthorn yogurt were 94.57% and 83.11%, respectively, while those of the control yogurt were 72.27% and 72.87%. During 4 ℃ storage period, the prolonged refrigeration time and the environment of gastrointestinal juice would lead to the decrease of free radical scavenging rate of the two kinds of yogurt, but the yam and hawthorn yogurt was still better than the control yogurt in general.