以昆仑十四号青稞苗为原料，探究超高压处理对青稞苗汁中多酚氧化酶（PPO）的影响，以保压压力、保压时间及pH为单因素，采用响应面法优化工艺过程，并确定多酚氧化酶最佳钝化条件为：保压压力为500 MPa、保压时间为25 min、pH为4.0，此时PPO残留酶活性为18.88%。通过对比超高压处理前后青稞苗汁理化指标变化，探究了保压压力和保压时间对青稞苗汁品质的影响。结果表明，随着压力增大和保压时间延长，微生物含量显著降低，达到国家要求的果蔬汁卫生标准；pH变化不显著；总花色苷、总黄酮、总酚含量比未超高压组含量增加显著，说明超高压处理能更好地保持青稞苗汁的品质。

Kunlun No.14 highland barley seedlings are used as raw materials to explore the effects of ultra-high pressure treatment on polyphenol oxidase in highland barley seedling juice.Response surface methodology is utilized to optimize the process by taking the holding pressure,holding time and pH as single factors.The optimal passivation conditions for polyphenol oxidase are determined as follows:the activity of polyphenol oxidase residual enzyme is 18.88% when the holding pressure is 500 MPa,the holding time is 25 min,and pH is 4.0.Through comparing the changes of physical and chemical indexes of highland barley seedling juice before and after ultra-high pressure treatment,the effects of holding pressure and holding time on the quality of highland barley seedling juice are explored.It is found that the content of microbials in the juice decreases significantly with the higher pressure and the prolonging holding time,which reaches China's health standard for fruit and vegetable juice.pH changes are not significant.The contents of total anthocyanins,total flavonoids and total phenols increases significantly compared with those in the non ultra-high pressure group,indicating that ultra-high pressure treatment can better maintain the quality of highland barley seedling juice.

甘文梅(1992-),女,硕士研究生,研究方向为天然产物分离与提取,912518@163.com