Study on the Regulation of Browning of Concentrated Orange Juice by Ultrasonic-Vacuum Combined with High-Pressure CO2 During Storage

Orange juice shows browning issue during storage which seriously affects its quality. Based on our previous study demonstrating the inhibition of browning of concentrated orange juice (COJ) by epigallocatechin gallate (EGCG) and L-cysteine (L-cys), this study evaluated the effect of ultrasonic-vacuum combined with high-pressure CO2 on browning. Ultrasonic-vacuum can reduce the dissolved oxygen content in COJ more effectively than ultrasonic and also minimize the loss of ascorbic acid. The lowest dissolved oxygen content and ascorbic acid loss in COJ were achieved by ultrasonic-vacuum at 900 W and 15.6 min for COJ sample of 50.0 g. Ultrasonic-vacuum effectively removes most of the dissolved oxygen from COJ, and high-pressure CO2 reduces oxygen in the headspace of the container. This reduction in oxygen content effectively reduces aerobic acid degradation and inhibits browning caused by ascorbic acid degradation. In addition, the results showed that although ultrasonic-vacuum combined with high-pressure CO2 had a significant effect on delaying ascorbic acid degradation and reduced the loss by 35.01%, it has little effect on browning caused by Maillard reaction. Finally, it is concluded that ultrasonic-vacuum combined with high-pressure CO2 based on EGCG and L-cys has the best inhibitory effect on browning of COJ during storage, inhibiting 69.8% of the increase in BI values.