Abstract:
To investigate the effects of different sterilization methods and storage temperatures on the quality changes of grape juice, this study examined four grape varieties characteristic of Xinjiang (Kyoho, Summer Black, Red Globe, and Thompson Seedless) as subjects. We compared two sterilization methods: pasteurization (90 °C/10 min) and ultra-high pressure sterilization (400 MPa/16 min). The study analyzed changes in microbial, physicochemical, and nutritional indicators of grape juice treated with these methods during storage at 4 °C and 25 °C. The results showed that both pasteurization treatment and ultra-high pressure sterilization treatment could effectively inhibit the microbial growth of the juice during the 35-day storage period, maintaining the juice in a commercially sterile state throughout. Simultaneously, combining both sterilization methods with low-temperature storage better preserved the sensory and nutritional qualities of grape juice. The pH levels of grape juice treated with different sterilization methods remained stable during the initial storage period but showed a declining trend in the later stages (
P<0.05). Compared to other treatment groups, pasteurization combined with 4 °C storage was more effective in maintaining the color of all four grape juice samples. Compared to pasteurization, ultra-high pressure sterilization combined with low-temperature storage could delay the degradation of reducing sugar and total acidity, thereby better preserving phenolic compounds and flavonoids. Ultra-high pressure sterilization combined with 4 °C storage resulted in the following reducing sugar retention rates for four grape juices: Kyoho (91.56%), Summer Black (91.41%), Thompson Seedless (93.17%), and Red Globe (86.48%); Total acid retention rates were 97.17%, 96.28%, 92.88%, and 97.74%, respectively; Total phenolic retention rates were 80.44%, 93.98%, 90.12%, and 89.11%, respectively; Flavonoid retention rates were 84.21%, 91.55%, 85.47%, and 83.16%, respectively. In conclusion, both pasteurization and ultra-high pressure sterilization demonstrated effective sterilization results for all four grape juice samples. However, ultra-high pressure sterilization showed superior advantages in preserving the nutritional quality of grape juice. When combined with cold storage, it helped delay quality deterioration and facilitated the retention of nutrients. This provided a theoretical basis and technical reference for grape juice processing, storage, preservation techniques, and extending shelf life.