超高压处理对鲜切冬瓜保鲜效果的影响

【目的】研究超高压处理对鲜切冬瓜的保鲜效果,为鲜切冬瓜的保鲜提供新途径。【方法】在25℃下将鲜切冬瓜分别采用200、400和600 MPa加压处理10 min,再于4℃下贮藏9 d,以未经超高压处理为对照,每3 d测定1次鲜切冬瓜的细菌菌落总数、多酚氧化酶(PPO)活性、过氧化物酶(POD)活性、硬度和亮度。【结果】随贮藏时间的延长,鲜切冬瓜的细菌菌落总数、PPO和POD活性逐渐升高,硬度和亮度逐渐下降;贮藏至第9 d,对照冬瓜的细菌菌落总数、PPO活性、POD活性、硬度和亮度L*分别为7.17±0.13 logCFU、(120.3±1.2)%、(136.5±0.8)%、1210±69 g和32.5±0.9,而400 MPa处理的鲜切冬瓜分别为1.20±0.06 logCFU、(12.8±0.6)%、(9.2±0.5)%、2295±68 g和67.5±1.1,各项指标与对照存相比均在显著差异(P<0.05);200 MPa处理的鲜切冬瓜各项指标与对照间无显著差异(P>0.05,下同),600 MPa处理的鲜切冬瓜各项指标与400 MPa处理间也无显著差异。【结论】400 MPa以上超高压处理可杀灭鲜切冬瓜的微生物、抑制PPO和POD活性,有效保持硬度和亮度,保鲜期延长至9 d。

Effects of ultra high pressure on preservation of fresh-cut wax gourd slices

Objective]The present study was conducted to research the effects of ultra high pressure(UHP) treatment on preservation of fresh-cut wax gourd slices in order to provide new preservation method for fresh-cut wax gourd slices.[Method]Fresh-cut wax gourd slices were treated with 200, 400 and 600 MPa for 10 min at 25℃, and stored at 4℃for nine days. The fresh-cut wax gourd slices without UHP treatment were taken as control. Total bacterial colonies, polyphe-noloxidases(PPO) activity, peroxidase(POD) activity,hardness and lightness of the fresh-cut wax gourd slices were deter-mined every three days.[Result]As storage time expanded, total bacterial colonies, PPO activity and POD activity increased gradually but hardness and lightness declined. On the ninth day of storage, the control’s total bacterial colonies were 7.17±0.13 logCFU, PPO activity(120.3±1.2)%, POD activity(136.5±0.8)%, hardness 1210±69 g, lightness L* 32.5± 0.9. While the indexes of fresh-cut wax gourd slices which were treated with 400 MPa were as follows: total bacterial colonies 1.20±0.06 logCFU,PPO activity(12.8±0.6)%,POD activity(9.2±0.5)%,hardness 2295±68 g,lightness L* 67.5± 1.1. There were significant differences between the indexes and those of control(P<0.05). The indexes of fresh-cut wax gourd slices which were treated with 200 MPa had no significant differences with those of control(P>0.05, the same below). The indexes of fresh-cut wax gourd slices which were treated with 600 MPa had no significant difference with those of 400 MPa.[Conclusion]UHP over 400 MPa can kill the microorganisms in fresh-cut wax gourd slices, inhibit PPO and POD activi-ties,maintain hardness and lightness. The preservation period of fresh-cut wax gourd slices can be extended to nine days.