Effects of Ozonated Water on Microbial Growth, Quality Retention and Pesticide Residue Removal of Fresh-cut Onions

The native microflora survival and quality retention of fresh-cut onions treated by ozonated water (OW) with ozone concentration of 1.4 mg L−1, for 1, 3, and 5 min during storage at 4°C for 14 days were investigated. The pesticide residue removal effect of OW treatment for 5 min was also determined. The results show that all OW treatments significantly inhibited the growth of aerobic bacteria, coliforms, and yeasts during storage, with the OW treatment for 5 min allowing the lowest growth rates. OW treatment for 1 min significantly reduced the weight loss of fresh-cut onions during a longer storage time (8–14 d). All OW treatments reduced the respiration rate and the softening of fresh-cut onions, exhibiting better overall quality retention than the control samples. In addition, OW treatment for 5 min significantly reduced the residual levels of five tested pesticides (dimethyl dichlorovinyl phosphate, cypermethrin, chlorpyrifos, methomyl, and omethoate) compared with water treatment. These results indicate that treatment with OW is a promising strategy to control the microbial growth, preserve the quality and reduce pesticide residual of fresh-cut onions.Abbreviations OW: ozonated water; PCA: plate count agar; VRBA: violet red bile agar; PDA: potato dextrose agar; DDVP: dimethyl dichlorovinyl phosphate