Effect of CO₂ Stress Pretreatment and Electron Beam Irradiation on the Quality of NFC Apple Juice

The single processing technology is difficult to meet the multiple requirements of the NFC juice, such as maintaining the nutrition and flavor, reducing browning and sterilization. In order to explore the combined effect of stress pretreatment and sterilization technologies on NFC fruit juice, 50% CO₂ stress pretreatment was used before apple juice squeezed to study the influence of different stress intensity on sensory quality and nutritional quality of apple juice. The effects of electron beam irradiation and pasteurization on sensory and nutritional quality and bacteriologic effect of apple juice were also studied. The results showed that: 50% CO₂ stress pretreatment could significantly increase the total phenolic content, antioxidant activity and V_C content of the NFC apple juice (P<0.05). Stored for 48 h, the total phenolic content and total antioxidant capacity of the 60 min stressed apple juice group were 118.7% and 104% of the control, respectively. Moreover, the CO₂ stress treatment significantly decreased the browning degree of NFC juice (P<0.05). Compared with the control and pasteurized groups, the browning degree of 2 kGy irradiation group and 4 kGy irradiation group were significantly lower (P<0.05), the total phenolic content and aroma were also better maintained, among which the 4 kGy irradiation was more effective. In the same time, compared with the control group, the 2 kGy and 4 kGy electron beam irradiation groups had a significant antibacterial effect (P<0.05), which all met the requirements of the national standards. 50% CO₂ stress pre-treatment combined with 4 kGy electron beam irradiation sterilization can be used as a new NFC apple juice processing technique.