Liu Qian, Zhang Min, Fang Zhong-xiang, Rong Xiao-hong
State Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, 214122, Wuxi, Jiangsu, China.
J Sci Food Agric. 2014 Sep;94(12):2547-54. doi: 10.1002/jsfa.6594. Epub 2014 Mar 18.
The sterilization of vacuum-packaged Caixin (Brassica chinensis L.), which is a green-leafy vegetable and also a low-acid food, remains a difficult problem. In this study, effects of ZnO nanoparticles and microwave heating on the sterilization and product quality of vacuum-packaged Caixin were investigated.
Addition of ZnO nanoparticle suspension at 0.01-0.02 g kg(-1) reduced the number of bacterial colonies. The antibacterial activity was enhanced with the increased amount of ZnO nanoparticles. Microwave heating (915 and 2450 MHz) was used to sterilize Caixin samples. Samples had good product quality (better greenness, chroma and hue angle values, lower browning index and acceptable texture) and the lowest total colony number under the microwave heating condition of 400 W 150 s (2450 MHz).
The best sterilization condition was observed under 2450 MHz microwave (400 W 150 s) heating combined with 0.02 g kg(-1) ZnO nanoparticle addition, which led to a total colony number of <1 log CFU g(-1) in Caixin samples within 7 days.
绿叶蔬菜小白菜属于低酸性食品，其真空包装后的杀菌仍是一个难题。本研究考察了氧化锌纳米颗粒和微波加热对真空包装小白菜杀菌及产品品质的影响。
添加0.01 - 0.02 g·kg⁻¹的氧化锌纳米颗粒悬浮液可减少菌落数。随着氧化锌纳米颗粒用量的增加，抗菌活性增强。采用微波加热（915和2450 MHz）对小白菜样品进行杀菌。在400 W 150 s（2450 MHz）的微波加热条件下，样品具有良好的产品品质（较好的绿色度、色度和色相角值，较低的褐变指数和可接受的质地）且菌落总数最低。
观察到最佳杀菌条件为2450 MHz微波（400 W 150 s）加热并添加0.02 g·kg⁻¹氧化锌纳米颗粒，此条件下小白菜样品在7天内的菌落总数<1 log CFU·g⁻¹。
