Control of apple surface microflora for fresh-cut produce by post-harvest hot-water treatment

Growing interest in a healthy and convenient diet causes a strong increase in the consumption of packaged fruit salads. Frequently, apple slices are a microbial problematic component. Apples are processed with their peel, which increases the consumers health risk and decreases the shelf life of fruit salads. Consequently, specific preprocessing sanitizing efforts directly during fresh fruit salad production are indispensable. Therefore, the study focused on the effective reduction of the microbial load of apples, particularly concentrating on human pathogens. Short-term hot-water treatment (HWT) actually controlled the microflora of apple surface if applied directly before processing. A HWT of 55 °C for 0.5 - 2 min efficiently reduced the natural microflora and artificial inoculated microbes on the apple peel for 2 - 3 log steps (i.e. 100 - 1000-fold) and yielded the best balance between preservation of the fruit and sanitation effect. Simply washing off the microorganisms (MOs) could be excluded as mechanism of hot-water disinfection. Due to complete waiving of any chemicals, short-term HWT is not only an efficient but also very gentle method to improve safety and shelf-life of fresh fruit salads. In addition, the proposed system could be easily and cost-effective integrated in existing production lines.