Operating conditions for microwave application throughout production process to reduce microbial load of fresh-cut apples

Consumers increasingly demand for convenient and healthy products such as fresh-cut fruits and vegetables. An important issue is the product safety, conventionally controlled using chemical sanitizing agents. High power/short time microwave-assisted heating could be used to improve quality and safety of high-convenience fresh produce by delaying quality losses and reducing microbial load, the use of sanitizing agents. Microwave as a postharvest treatment has not yet been largely studied. Application of mild-heat treatments is used in this work at different stages of the production process in order to prolong the shelf-life and improve quality and safety of fresh-cut apples. Two power/time combinations were applied before and after washing the apple slices (35 s/300 Watt of output power and 10 s (100 W)-1). Physico-chemical, organoleptic and microbiological analysis were carried out on representative samples after treatment and during storage time. Results showed that the treatment 300 W (35 s)-1after washing, gave a greater microbial reduction compared to control samples washed with 30 ppm NaClO, without adverse effect on nutritional aspects. Microwaving was applied before and after packaging and it was observed that apple slices treated after packaging reached 1.4 log CFU g-1reduction of microbial load during 14 days storage. However, the samples treated and packaged showed a slight decrease of visual quality. Additional treatment with calcium ascorbate or natural anti-browning agents may be considered in order to maintain product quality. From the results obtained it is possible to conclude that microwave treatment, eventually together with anti-browning treatment, could represent a good, effective and sustainable alternative to NaClO in terms of reduction of chemicals and water consumption.