Red cabbage washing with acidic electrolysed water: Effects on microbial quality and physicochemical properties
Chen, X., Xue, S.J., Shi, J., Kostrzynska, M., Tang, J., Guévremont, E., Villeneuve, S., Mondor, M. (2018). Red cabbage washing with acidic electrolysed water: Effects on microbial quality and physicochemical properties. Food Quality and Safety, [online] 2(4), 229-237. http://dx.doi.org/10.1093/fqsafe/fyy023
Plain language summary
Red cabbage is one of the world’s most widely consumed fresh-cut vegetables with high nutritional values relating to the antioxidants and anti-inflammatory activity of anthocyanins, vitamins, and minerals. However, frequent incidence of food disease outbreaks associated with the consumption of fresh-cut vegetables and fruits have also been a major concern. It is well known that anthocyanins are very unstable and easily degradable since they are sensitive to factors like oxygen, temperature, pH, light, etc. Poor cleaning and sanitizing processes may increase the risk of foodborne outbreaks leading to public health concerns. In addition,
economic losses may occur to the food industry due to product recalls, legal, and customer claims. Electrolysed water (EW) as ‘green’ process and technology is a relatively novel disinfecting solution that has been shown to effectively reduce pathogenic bacteria on fresh produces
without any chemical residues. The acidic electrolysed water (AEW) contains hypochlorous acid, a weak acid. It has strong oxidation potential,
and a shortage of electrons giving it the ability to oxidize and destroy microbes as well as toxins. Therefore, AEW can be used as a disinfectant
and an antimicrobial agent. It is well known that the treatments with AEW have many advantages in the decontamination of vegetables and
fruits including without impact on the tissue pH, surface colour, general appearance, customer acceptance, and no off-odour or off-flavour
production. In recent years, AEW as ‘green’ process and technology has gained interest as a bactericide against a variety of microorganisms, to remove pesticide residues, and to reduce mycotoxin attributes on the applications of agriculture harvest, supermarket, and food industry.
Salmonella is the most frequently reported cause of foodborne illness and morbidity in humans. It is one of the serious pathogens that have been responsible for food outbreaks in meats, ready-to-eat products, minimally processed foods, fresh produce, and fresh-cut products. The fresh produces (vegetables and fruits) can be contaminated with Salmonella from environmental sources, distribution/storage, food preparation, and food handling processes. Salmonella must be killed on food before consumption. The AEW treatment has advantages associated with its low cost, ease of operation, and ability to remove dirt and inactivate microbes simultaneously. However, the available chlorine concentration (ACC) of AEW and treatment time may greatly influence its antimicrobial activity and bioactivity of phenolic compounds present in fresh-cut produces. Therefore, the aim of the present study was to evaluate the effects of ACC of AEW and treatment time on the inactivation efficacy of native microflora and artificially inoculated S. typhimurium DT104 on the red cabbage. The contamination of processing water that were collected after treatments have also been determined in order to know whether those washing water required post-decontamination treatment before they discharged or released from fresh-cut produce industry. In addition, the influences of AEW on the physicochemical properties, colour, pH, total phenolic contents, anthocyanins, and antioxidants were investigated.
The effects of acidic electrolysed water (AEW) as 'green' technology on the microbiological and physicochemical properties of fresh-cut red cabbages were studied. Fresh-cut red cabbages and artificially inoculated red cabbages with Salmonella typhimurium DT104 were washed with distilled water (DW) and different available chlorine concentrations (ACC) of AEW for different times. AEW treatments significantly reduced the populations of native aerobic bacteria, molds, and yeasts, and artificially inoculated S. typhimurium DT104 compared with the DW-treated and untreated red cabbage samples. The effectiveness of AEW treatments was greatly enhanced with increasing ACC and treatment times. S. typhimurium DT104 were not detected in the washing water that were collected after the red cabbages treated by AEW. The surface colour, pH, and total phenolic contents did not significantly change when the red cabbages were washed with DW and AEW containing 100 mg/L available chlorine for 3 min. The anthocyanin contents and antioxidant activities of red cabbage were significantly reduced by 18.5 per cent for cyanidin, 22.1 per cent for pelargonidin, and 11.2 per cent for 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, however, the impacts on the nutritional benefits of red cabbage were considered as limited and acceptable. The optimal process condition of AEW for washing red cabbage was 100 mg/L ACC for 3 min. In these conditions, most of the native microflora were inactivated, and artificially inoculated S. typhimurium DT104 on the red cabbage were reduced by 40.2 per cent [3.67 log CFU/g (log10 colony-forming units per gram)] and with minimal losses of nutrients and antioxidant activity, as well as no requirement of decontamination treatment on the washing water after AEW treatment.