Development of innovative technologies for fruit products processing

This PhD thesis project dealt with the development of innovative technologies for processing of different type of plant-based products in order to maintain and/or increase their quality and stability. In particular, the technologies studied during PhD project were: pulsed electric field (PEF), ohmic heating (OH), high pressure of homogenization (HPH) and innovative edible coating (EC). Different experimental procedures were set up by performing the following independent case of studies: i) PEF pre-treatment on osmo-dehydrated strawberries; ii) PEF pre-treatment (with or without osmotic dehydration - OD) on kiwifruit slices before air-drying; iii) PEF and OH treatments on carrot and apple mash; iv) HPH application on mandarin and organic kiwifruit juice; v) application of innovative EC on blueberry fruits. Based on the obtained results, the application of PEF treatment at low field strength and the use of trehalose for the osmo-dehydration process seems to be an optimal combination for obtaining a semi-dried strawberry product with quality characteristics similar to the fresh one. Thermal treatment followed by PEF or conducted by OH improve the cell disintegration and juice yield; a controlled application of high temperature may contribute to the inactivation of enzymes, reflected by improved colour and the release of polyphenols. The application of HPH on fruit juice production contributes to guarantee the protecting effect of trehalose on mandarin juice structure during storage and allows obtaining stable kiwifruit juice for more than 40 days under refrigerated storage. For what concern the innovative packaging solutions, the use of different EC showed positive effects on firmness, colour retention and contributed to the increase of antioxidant activity of blueberry fruits. The results of this PhD research work can greatly contribute to obtain high quality fruit/vegetable processed products in an efficient and environmentally sustainable way, thus determining an added value for food companies.