Effects of ZnO nanoparticles and microwave heating on the sterilization and product quality of vacuum-packaged Caixin.
BACKGROUND
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.


RESULTS
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).


CONCLUSIONS
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.
State Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, 214122, Wuxi, Jiangsu, China.
Qian
Q
Liu
Min
M
Zhang
Zhong-xiang
ZX
Fang
Xiao-hong
XH
Rong
D000900:Anti-Bacterial Agents; D001419:Bacteria; D001937:Brassica / Q000382:microbiology; D015169:Colony Count, Microbial; D003116:Color; D003296:Cooking; D004032:Diet; D005516:Food Microbiology; D018857:Food Packaging / Q000379:methods*; D005519:Food Preservation; D063427:Food Quality; D006361:Heating / Q000379:methods; D006358:Hot Temperature; D006801:Humans; D008872:Microwaves; D053758:Nanoparticles; D018515:Plant Leaves; D013242:Sterilization; D014618:Vacuum; D014675:Vegetables; D015034:Zinc Oxide
D000900:Anti-Bacterial Agents; D015034:Zinc Oxide
ZnO nanoparticles; microwave heating; product quality; total colony number; vacuum-packaged Caixin