Food Science Department, Faculty of Agriculture, Cairo University, Giza, Egypt.
Food Technology Department, Food Industries and Nutrition Institute, National Research Centre, Cairo, Egypt.
Food Sci Technol Int. 2023 Oct;29(7):757-764. doi: 10.1177/10820132221117750. Epub 2022 Aug 4.
The effect of the UV-C treatment on the physico-chemical characteristics, pectin methylesterase activity (PME) as well as microbial quality of orange juice, compared to fresh juice, was studied. The juice samples were UV-C (254 nm) irradiated for different exposure times (15, 30, 45 and 60 min) and stored at 4 ± 1 °C for 30 days. UV-C treatment didn't significantly ( ≤ 0.05) affect pH values, titratable acidity, TSS (%), ascorbic acid content and PME activity in both fresh and stored samples. Increasing the exposure time from 5 to 60 min. showed no significant effect ( ≤ 0.05) on L* and a* values for both the fresh and the stored samples. On the contrary, negative relationship was observed between UV-C exposure time and b* values. Total bacterial counts were significantly ( ≤ 0.05) reduced from 2.69 to 0.93 log CFU/mL when the exposure time was increased from 0 to 60 min. The UV-C treatment showed similar trend on yeast and mold counts but to a lesser extend due to their resistance to UV. The sensory characteristics, i.e. odour, colour, taste, consistency and overall acceptability didn't change ( ≤ 0.05) as a result of UV-C treatment at any tested exposure times.
研究了与新鲜橙汁相比，紫外线-C（UV-C）处理对橙汁理化特性、果胶甲酯酶活性（PME）以及微生物质量的影响。将橙汁样品用不同的紫外线-C（254nm）照射时间（15、30、45 和 60 分钟）进行照射，并在 4±1°C下储存 30 天。紫外线-C 处理对新鲜和储存样品的 pH 值、可滴定酸度、总可溶性固体（TSS）（%）、抗坏血酸含量和 PME 活性没有显著影响（≤0.05）。增加暴露时间从 5 分钟增加到 60 分钟，对新鲜和储存样品的 L和 a值均无显著影响（≤0.05）。相反，紫外线-C 暴露时间与 b*值呈负相关。当暴露时间从 0 分钟增加到 60 分钟时，总细菌计数从 2.69 减少到 0.93 log CFU/mL，差异有统计学意义（≤0.05）。紫外线-C 处理对酵母和霉菌计数也表现出相似的趋势，但由于其对紫外线的抵抗力，效果较小。感官特性，即气味、颜色、味道、稠度和总体可接受性，在任何测试的暴露时间下均未因紫外线-C 处理而发生变化（≤0.05）。
