Investigation Of Slightly Acidic Electrolyzed Water And Ultrasonic Treatment On Surface Decontamination And Preservation Of Fresh Fruits And Vegetables

At a pH of5.0-6.5, slightly acidic electrolyzed water (SAEW) is recognized as a novel antimicrobial agent. Ultrasonic treatment is capable of inactivating some microorganisms, and it has been recommended as an alternative sanitization step in the fresh produce industry. The investigations of acidic electrolyzed water and ultrasound treatment used as pre-treatment methods, have gained much attention in recent years. Based on the bactericidal property of SAEW, the effect of ultrasonic treatment on the physicochemical properties (pH, ACC, ORP, spectrophotometric characteristics) of SAEW was studied. Experiments were also performed to investigate the possibility of ultrasound and SAEW applied in the preservation of cherry tomatoes and immature strawberries. The main research results were presented as follows:1. SAEW is effective in reducing microorganisms on the surface of fruits and vegetables and no cells of any of the microorganisms studied were detected in SAEW solution after the treatment, which suggested that SAEW could prevent cross-contamination of fresh produce in the cleaning process.2. SAEW at60℃showed the best bactericidal activity, leading to a reduction of2.62,2.88,3.661g CFU/g for total aerobic bacteria, yeast and mold, Salmonella Typhimurium, respectively. Moreover, all quality parameters of cherry tomatoes didn’t suffer any alterations. It was also observed that the pH、 ORP of SAEW didn’t change and the ACC decreased a bit at60℃after the treatment.3. Ultrasonic treatment had no effect on properties of SAEW. Ultrasound could enhance the germicidal efficiency of SAEW and the combination treatment provided greater microbial reduction. It is inferred that SAEW in combination with appropriate ultrasound treatment could be a promising sanitization treatment to improve the germicidal efficiency on fresh produce without compromising the quality.4. Cherry tomatoes used as the sample, ultrasound treatment significantly removed about0.96and0.681g CFU/g for total aerobic bacteria and yeast and mold, respectively. SAEW reduced about1.451g CFU/g for total aerobic bacteria and1.001g CFU/g for yeast and mold. And the treated samples also maintained relatively low microbial loads during storage. It was also observed that ultrasound or SAEW treatment also decreased the decay incidence and respiration rate of cherry tomatoes. The two treatments inhibited the decrease in soluble solids content without any effect on hardness, titratable acidity and vitamin C content. Results showed that both ultrasound and SAEW have potential to ensure the microbial safety and decrease the decay incidence of cherry tomatoes.5. Immature strawberries used as the sample, ultrasound and SAEW alone or combined significantly removed about0.52,1.07,1.291g CFU/g for total aerobic bacteria and0.30,0.93,1.181g CFU/g for yeast and mold, respectively. And the treated samples also maintained relatively low microbial loads during storage. It was also observed that the three treatments increased the respiration rate of strawberry. The treatments increased the content of soluble solids, vitamin C and anthocyanin during storage. It was also found that ultrasound inhibited the decrease of firmness. Results showed that both ultrasound and SAEW have potential to ensure the microbial safety as well as improve the quality of immature strawberry.