Evaluation of vegetable washing chemicals
Vegetables, including leafy vegetables, are an important component of a healthy diet; they contain nutrients that are now known to be beneficial for the health of consumers. These nutrients are often referred to as phytochemicals or phytonutrients. They have a range of actions on the human body through their interaction at the cellular level. There is sufficient information in the literature to show that they protect consumers from heart disease, inflammation, cancer formation and many other chronic diseases. The anti cancer properties of phytonutrients can be due to a number of interactions, including the induction of phase I or II detoxification enzymes, modulation of phase I and other enzyme activities, antioxidant activity, electrophile scavenging activity, inhibition of nitrosation, and/or modulation of oncogene or protooncogene expression or function. Health authorities are actively encouraging the consumption of vegetables through their 5 a day or 7 a day campaigns. This is having an effect on the consumption patterns in developed countries with consumers being more aware of the importance of vegetables in their diets. There is however a perception that vegetables, and in particular leafy vegetables, can be the source of food poisoning outbreaks. This has in fact been an issue overseas in recent years, with severe outbreaks reported in the USA and Germany due to human pathogen contamination of vegetables. In Australia this has not been an issue, due mostly to the successful implementation of on-farm QA plans that growers must follow before they can sell their products to consumers through markets and supermarkets. Part of the requirements of a good on-farm QA plan is the sanitary washing of vegetables, especially leafy vegetables, in water containing a sanitiser chemical. This sanitation step will reduce the levels of bacteria, including any contaminating human pathogens, and prevent cross contamination of produce during the washing stage. In Australia there have been many chemicals available to growers, however growers do not have much independent information available regarding these chemicals. This project has evaluated a number of chemicals and compared them in terms of efficacy, ease of use, cost and effects on the postharvest shelf life of leafy vegetables. The results show that Chlorine, as used currently by growers, is still an efficient way to achieve the aims of the sanitation step. An emerging technology using electrified oxidizing water has however shown excellent results and could become a very useful tool for the sanitary washing of vegetables at on-farm level in the near future. The process would fulfil a chemical free washing claim and also be user friendly for the grower; it can be easily adapted to an automatic system with record of efficacy available for review by auditors of on-farm QA systems.