Effects Of Non-thermal Technology On The Quality Of Fresh Apple Juice

This paper studied the effects of UV-C,ultrasonic(US)and ultrahigh pressure(UHP)processing on color,physiochemical properties,total phenol and flavonoids content,antioxidant capacity and enzyme activity in fresh apple juice.Based on the above results,we compared the effect of three non-thermal technologies on color,total phenol,flavonoids content and the antioxidant capacity in short-term storage of apple juice.The major research contents and conclusions were as follows:(1)UV-C treatment about 244-731 mJ/cm~2 significantly reduced the Browning Index(BI)and POD activity,color change was slightly noticeable(?E<2);all treatments had no significant effect on pH and titratable acid(TA),but the soluble solids(TSS),total flavonoids content and antioxidant capacity increased significantly(P<0.05).UV-C treatment at 487 mJ/cm~2 showed the best results.(2)US(20-60 min)markedly reduced the BI,turbidity and POD activity(P<0.05),and the color change was slightly noticeable(?E<2);all treatments had no significant effect on pH and TA,but significantly raised the content of TSS(P<0.05);the total phenol,flavonoids content and ABTS radical scavenging rate increased more by 40 and 60 min US processing than 20 min treatment.40 min ultrasonic treatment was the best.(3)UHP(100-400 MPa)significantly reduced the BI,pH,turbidity,and POD activity(P<0.05),the color change was slightly noticeable(?E<2);all treatments had no significant effect of TA and PPO activity;the total phenol and flavonoids content and antioxidant capacity treated by 300 and 400 MPa ultra-high pressure had no significant difference with control(P>0.05),however,the content of total phenol treated by 300 MPa UHP was the most,up to 945.42 GAE ?g/mL.(4)The quality of apple juice respectively treated with 487 mJ/cm~2 UV-C,40 min US,and 300 MPa UHP during 12 days storage were studied.As the storage time prolonged,L* value,total phenol and flavonoids and antioxidant activity showed lower trend of all treatments,but a *,b *,?E and BI were significantly increased(P<0.05);total phenol and flavonoids content and antioxidant activity treated by UV-C,US and UHP were significantly higher than that of control during storage period(P<0.05);among them,40 min US was the best.