菠菜毒死蜱消解动态及采后清洗对菠菜安全的影响

对春季露地菠菜生产中常用农药毒死蜱的消解动态,以及采后清洗对菠菜毒死蜱残留及微生物数量的影响进行了研究。结果表明:春季露地菠菜毒死蜱(48%乳油)750倍液喷施,其一级消解动力学模型为C=9.5422e-0.361t,半衰期1.92d,达到GB2763—2005中叶菜类毒死蜱最大残留限量0.1mg·kg-1的理论安全间隔期为12.6d;采后用自来水、ClO25mg·kg-1、ClO210mg·kg-1、NaClO100mg·kg-1和超声波(26kHz、450W)分别清洗1min,均可减少1log的细菌总数,但ClO210mg·kg-1处理后发现仍存在270cfu·g-1大肠菌群,表明生产中即使采用消毒剂清洗菠菜,其微生物安全性仍存在不确定性;研究中还发现,生产中常用的NaClO具有减少毒死蜱残留量的作用;此外,超声波是一种很好的辅助清洗技术,有助于减少菠菜毒死蜱残留量及微生物数量。鉴于单一清洗消毒方式在保证菠菜采后食用安全方面的不确定性,今后采用两种或两种以上的联合清洗消毒技术将有助于进一步改善菠菜乃至果蔬产品的采后安全。

Vanish Dynamics of Chlorpyrifos in Spinach and Effect of Post-harvest Washing on Spinach Safety

The residue vanish dynamics of chlorpyrifos in spring open-field spinach（Spinacia oleracea L.）after sprayed with 750 fold dosage（48 % emulsion）, and the effect of post-harvest washing on microbe and chlorpyrifos of spinach were investigated to direct the safety management of spinach from field to market. The results showed that the first class degradation dynamic model of chlorpyrifos in spinach was C＝9.542 2e^{-0.361 t}，which predicted the half-life period of chlorpyrifos was 1.92 d, and the safe interval time for spring open-field spinach was 12.6 days when met the standard of GB 2763—2005, which required maximum residue limit of chlorpyrifos was 0.1 mg·kg^-1. Postharvest washing for 1 minute by tap water, 5 mg·kg^-1 chlorine dioxide（ClO₂）, 10 mg·kg^-1 ClO₂, 100 mg·kg^-1 hypochlorite（NaClO）and ultrasonic（26 kHz and 450 W）respectively reduced 1 log total bacterial counts, but there still existed 270 cfu·g^-1 coliform after treated by 10 mg·kg^-1 ClO₂, which meant the microbe safety was still a problem, even if some disinfectants were used for commercial washing. NaClO was found to help reducing the residue of chlorpyrifos and ultrasonic was a good washing assistant technology for reducing the residue of chlorpyrifos and microbe counts. The single washing and disinfecting technology could not entirely assure the safety of spinach, so the combined technologies including two or more technologies were suggested to improve the safety of spinach and postharvest fruits and vegetables.