Use of Acetic Acid to Partially Replace Lactic Acid for Decontamination against Escherichia coli O157:H7 in Fresh Produce and Mechanism of Action

Abstract

Escherichia coli O157:H7 is frequently detected in ready-to-eat produce and causes serious food-borne diseases. The decontamination efficacy of lactic acid (LA) is clearly established. In this study, LA was mixed with acetic acid (AA) to reduce costs while achieving consistent or better inhibitory effects. Time-kill curves and inoculation experiments using fresh-cut spinach and arugula indicated that 0.8%LA+0.2%AA shows similar antibacterial effects to those of 1%LA. To determine whether 1%LA and 0.8%LA+0.2%AA exert antibacterial effects by similar mechanisms, proteomics analysis was used. The proteins related to macromolecule localization, cellular localization, and protein unfolding were uniquely altered after the treatment with 1%LA, and the proteins related to taxis, response to stress, catabolic process, and the regulation of molecular function were uniquely altered after the treatment with 0.8%LA+0.2%AA. Based on these findings, combined with the results of a network clustering analysis, we speculate that cell membrane damage is greater in response to LA than to 0.8%LA+0.2%AA. This prediction was supported by cell membrane permeability experiments (analyses of protein, nucleotide, ATP, and alkaline phosphatase leakage), which showed that LA causes greater membrane damage than 0.8%LA+0.2%AA. These results provide a theoretical basis for the application of an acid mixture to replace LA for produce decontamination.

Effects of ultrasound-assisted low-concentration chlorine washing on ready-to-eat winter jujube (Zizyphus jujuba Mill. cv. Dongzao): Cross-contamination prevention, decontamination efficacy, and fruit quality

“…However, ultrasonic-induced mechanical damage may deteriorate the quality of produce, leading to browning, and weight and nutrition loss. Such deterioration cannot be observed immediately after treatment; thus, quality analysis was performed at the end of storage (day 7), which is consistent with findings of previous studies [4] , [29] , [42] . The weight loss was not significantly different between the treatment and control groups ( Fig.…”

Use of aqueous ozone rinsing to improve the disinfection efficacy and shorten the processing time of ultrasound-assisted washing of fresh produce

“…Among these combinations, the US–chlorine + 1.0 ppm AO treatment resulted in the lowest counts of E. coli O157:H7 and S. Typhimurium considering the two COD conditions; thus, the US–chlorine + 1.0 ppm AO treatment was selected for comparison with the AO-only and US–chlorine + TW treatments in terms of their abilities to damage pathogen membranes. When the cell membrane is broken, ATP, AKP, proteins, and nucleotides leak out, and the extent of this leakage reflects the degree of change in the cell membrane integrity [ [29] , [48] ]. Thus, our results indicated significantly higher ATP, AKP, proteins, and nucleotides leakage levels after US–chlorine + 1.0 ppm AO treatment than after the US–chlorine + TW treatment ( Fig.…”

“…Cell membrane integrity was analyzed according to the method reported by Wang et al [ 29 ]. Sterilized TW (120 s) alone was included as a control treatment, and 1 ppm AO (120 s), US–chlorine (60 s) + TW (60 s), and US–chlorine (40 s) + 1 ppm AO (60 s) were the experimental treatments.…”

Antimicrobial Activity of a Vaginal Gel Formulation: Considerations Related to Vaginal Infection and Dysbiosis

“…In this time-based experiment (Figure 3), rapid intrusion of propidium iodide into Gardnerella was observed but occurred more slowly with E. coli. Although the literature on lactic acid in compromising microbial membrane integrity is limited, a study on E. coli 0157:H7 showed 1% lactic acid to be effective in causing solute leakage from membranes [28]. However, based on the estimated concentration of lactic acid in a forty-fold dilution, the lactic acid would probably be insufficient by itself to induce membrane damage.…”