Abstract:  In this study, slightly electrolyzed oxidizing water (SEOW) was used to treat fresh spinach. The bactericidal effect of SEOW and its factors were explored through the comparison among different antiseptics. Meanwhile, the effects of soaking time, treatment mode and pretreatment of strong alkali electrolyzed water on bactericidal activity were investigated. Moreover, the changes in available chlorine of concentration (ACC), pH and oxidation-reduction potential (ORP) during the treatment process were also analyzed. The results showed that the bactericidal effect of SEOW with ACC 31.73 mg/L, pH 5.92 and ORP 836.5 mV was obviously higher than sodium hypochlorite solution with the same concentration of ACC. In addition, increasing ACC could gradually improve the bactericidal effect of SEOW. The number of microorganisms on spinach surface was decreased by 1.69 (lg(CFU/g))when the concentration of ACC was increased to 31.37 mg/L; however, no obviously enhanced bactericidal effect was observed when the concentration of ACC was increased to 67.96 mg/L. Similarly, the bactericidal effect of SEOW did not reveal a significant difference among the soaking times of 1, 3, 5min and 10 min, respectively. But both ACC and ORP exhibited a significant declination during the extension of soaking time although the pH still remained stable. Furthermore, the pre-treatment of strong alkali electrolyzed water and ultrasonic-assisted treatment could result in the enhancement of sterilization rate by 0.5(lg(CFU/g)) and 1.0 (lg(CFU/g)), respectively. Therefore, better bactericidal effect was observed for fresh spinach by soaking in SEOW than flushing with SEOW.

Key words: slightly electrolyzed oxidizing water, spinach, sterilization