不同加工条件下桑椹膏在熬制过程中的糖分含量及体外抗氧化活性变化

Changes of Sugar Content and Antioxidant Activity in Mulberry Fruit Jam During Cooking Under Different Processing Conditions

以桑椹原浆为原料熬制桑椹膏,设置电磁炉加热功率为400 W、800 W,桑椹原浆与水的体积比为1∶1和1∶2,并组合为4组加工条件,检测分析不同加工条件下桑椹膏在熬制过程中的总糖、葡萄糖、果糖、蔗糖含量及体外抗氧化活性变化。4组条件下桑椹膏熬制过程中的总糖含量变化较小,葡萄糖含量不断升高,果糖含量则逐渐下降,除桑椹原浆与水的体积比为1∶1、加热功率800 W条件下熬制桑椹膏的葡萄糖和果糖含量较高外,其余3组条件下熬制桑椹膏中的葡萄糖和果糖含量差异较小;桑椹膏的体外总抗氧化能力以及对超氧阴离子自由基和羟自由基的清除活性随着熬制时间的延长逐步下降。试验结果提示,在桑椹膏熬制过程中果糖要先于葡萄糖参与美拉德反应,过长的熬制时间会影响桑椹膏产品的抗氧化活性,加工条件以桑椹原浆与水体积比为1∶1、加热功率为400 W较佳,能较好地保持桑椹膏的营养与保健品质。

Mulberry fruit puree was used as raw material to prepare mulberry fruit jam by setting the heating power of electromagnetic oven at 400 W and 800 W and the volume ratio of mulberry fruit puree to water at 1 ： 1 and 1：2, which were combined to form 4 processing conditions. The changes of total sugar, glucose, fructose and sucrose contents and in vitro antioxidant activity of mulberry fruit jam during cooking under different processing conditions were measured and analyzed. The results showed that, during cooking at 4 different processing conditions, total sugar content changed very little, glu- cose content increased continuously, while fructose content decreased gradually. At 1 ： 1 volume ratio of mulberry fruit pu- ree to water and heating power of 800 W, the obtained mulberry fruit jam had relatively high glucose and fructose contents. Under the rest 3 processing conditions, glucose and fructose contents in mulberry fruit jam had very little difference. The in vitro total antioxidant capacity, anti-superoxide anion capacity and hydroxyl radical scavenging capacity of mulberry fruit jam all decreased gradually with cooking time. These data demonstrate that, during cooking of mulberry fruit jam, fructoseparticipates in Maillard reaction earlier than glucose, and too long cooking time will reduce the antioxidant activity of mulberry fruit jam. 1 ： 1 volume ratio of mulberry puree to water and 400 W of heating power constitute a good pro- cessing condition for maintaining high nutrition and health- care quality of mulberry fruit jam.