中国农业大学赵靓副教授等|超高压和高温短时杀菌对 NFC 橙汁品质的影响

Orange juice is one of the most consumed juice in the world. However, it is mainly sterilized by conventional heat treatment, which will cause some of the heat-sensitive flavor and nutrients lost. High pressure processing (HPP) is a novel non-thermal processing technology, which could achieve effective pasteurization and regulation of enzyme activity at room temperature, and maintain the fresh quality of the food. In this study, the effects of HPP (600 MPa, 1 min) and high temperature short time (HTST, 110 ℃, 8.6 s) on microorganisms, basic physical and chemical indicators, color, stability, biologically active ingredients, antioxidant activity and other qualities of not from concentrate (NFC) orange juice were analyzed before and after treatment, and during 25 days of storage at 4 ℃. The results showed that after HPP and HTST treatment, the total number of total plate count, yeast & molds, lactic acid bacteria, and psychrotrophic bacteria of orange juice decreased below the detection limit (<10 CFU/mL). After 25 days of storage. All the microorganisms of HPP-treated orange juice were still not detected, while the total plate count and yeast & molds of HTST-treated orange juice began to grow. The total color difference (ΔE) of HPP-treated juice was lower than that of HTST-treated juice, and the color difference between HPP and untreated juice was small. Compared with the control, HPP treatment significantly increased the total phenol contents of orange juice by 13.50% (P<0.05), but showed no significant effect on vitamin C content, DPPH scavenging ability, FRAP iron ion reduction ability, and comprehensive sensory evaluation, while these indexes were significantly decreased after HTST treatment (P<0.05). After HPP and HTST treatment, the residual enzyme activities of pectin methylesterase (PME ) in orange juice were 92.31% and 14.42%, respectively, and at the end of storage, there were 30.77% and 0.03% residue activity still left, respectively. Because of the residual enzyme activity of PME, the suspension stability of HPP orange juice decreased by 95.45% during storage. In summary, HPP maintain the nutrition, sensory quality and fresh flavor of orange juice better than HTST treatment, however the inactivation of PME should be improved. The study provides a reference for the application of HPP in NFC orange juice.