肉苁蓉红枣复合酸奶制备工艺的响应面优化及其抗氧化活性的生物传感器评价

以肉苁蓉、红枣及酸奶为原料，以口感、组织状态、气味及色泽为评价指标，借助单因素实验和响应面曲线分析法对肉苁蓉红枣复合酸奶的制备工艺进行了优化，并利用DPPH 自由基清除体系和电化学生物传感器对复合酸奶的抗氧化活性进行了快速评价。由单因素实验和响应面分析法的结果可知，当红枣汁、肉苁蓉汁和蜂蜜的添加量为18%、8%和5%时，复合酸奶的品质最优，这时感官评分为92.2分，与预测值92.5分接近一致。在同等优化条件下，DNA、壳聚糖、氮掺杂石墨烯层层修饰玻碳电极所制备的DNA/CS-N-G/GCE生物传感器用于抗氧化活性评价时，L-抗坏血酸、复合酸奶和原味酸奶的电化学响应峰电流值依次为6.5×10?5、8.5×10?5、1.05×10?4 A，其活性大小依次为L-抗坏血酸>复合酸奶>原味酸奶。DPPH 自由基清除实验进一步验证显示，L-抗坏血酸、复合酸奶和原味酸奶的IC₅₀ 值依次为4.54、15.65和22.94 mg/mL，该结果与生物传感器的评价结果一致，且两种方法无显著性差异。上述结果表明原味酸奶中添加肉苁蓉、红枣提取物后显著增强了抑制自由基损伤DNA的作用，增加了复合酸奶的抗氧化性，构建的传感器可用于复合酸奶抗氧化活性的快速评价。

Response Surface Optimization of the Preparation Process of Compound Yogurt with Cistanche deserticola and Jujube and Evaluation of the Antioxidant Activity of Compound Yogurt with Biosensors

The preparation process of compound yogurt with added cistanche and jujube was optimized using single-factor experiments and response surface curve analysis by applying evaluation indicators including taste, texture, odor, and color. Besides, a rapid evaluation of the antioxidant activity of the compound yogurt was performed by employing the DPPH free radical scavenging system and electrochemical biosensors. Results of the single-factor experiments and response surface analysis indicated that the quality of the compound yogurt was optimal when the percentages of jujube juice, cistanche juice, and honey were 18%, 8%, and 5%, respectively. This composition achieved a sensory score of 92.2, which was close to the predicted score of 92.5. Under the same optimized conditions, the evaluation of the antioxidant activity with the preparation of DNA/CS-N-G/GCE biosensor obtained through the layer-by-layer modified glassy carbon electrode assembly of DNA, chitosan, and nitrogen-doped graphene indicated that L-ascorbic acid, compound yogurt, and plain yogurt present peak current values of 6.5×10?5、8.5×10?5 and 1.05×10?4 A, respectively. This represented a decreasing trend in antioxidant activity. Further validation of DPPH free radical scavenging experiments showed that the IC₅₀ value of L-ascorbic acid, compound yogurt and plain yogurt were 4.54, 15.65 and 22.94 mg/mL, respectively. This was consistent with the results of the evaluation of the compound yogurt using the biosensor, and there was no significant difference between the two methods. Therefore, the addition of cistanche and jujube extracts into plain yogurt significantly enhanced the inhibition of damage to DNA by free radicals, thus improving the antioxidant activity in the compound yogurt. The constructed sensor could be used for the rapid evaluation of antioxidant activity of compound yogurt.