Shelf-life extension of ready to use fresh apple slices using different combined techniques

The objective of the investigation was to study the effect of different modified atmosphere (MA) packaging, eventually combined with ethanol pre-treatments, on microbial growth, enzymatic browning and firmness changes of refrigerated apple slices. As respect to the air packaging, all the MAs studied were suitable in preventing enzymatic browning, but they differently influenced the microbial growth. Firmness was scarcely affected by MAs. Although enzymatic browning was successfully inhibited by the sole MA packaging, the combination of a dipping in a dilute ethanol solution with MA packaging was effective in slowing down darkening of the stored product even after pack opening to rate values similar to those found for a fresh product. Introduction Minimally processed fruit and vegetables are an important developing class of food products for their attractive attributes such as commodity and fresh-like quality. Nevertheless these products are generally more perishable than the original raw materials due to microbial spoilage and various enzymatic degradation reactions. In fact, operations such as peeling, cutting, shredding, slicing etc. greatly increase tissue respiration and lead to various biochemical damage such as browning, off-flavour development and texture breakdown. Moreover, the minimal processing can enhance microbial spoilage even through transfer of skin microflora to fruit tissue (1, 2, 3, 4). Besides refrigeration, an improvement of the shelf-life of the ready-to-use fresh fruit and vegetables may be achieved combining many of the classic preservation procedures such as chemicals (antioxidants and antimicrobials), modified atmospheres packaging, pH reduction and, to a lesser extent, water activity reduction (1, 4). Nevertheless, the choice of the suitable preservation procedures may result difficult considering the various and complex biochemical and microbiological changes that should be inhibited or slowed down. Most of the studies 3