Isothermal calorimetry studies on the stability of fresh-cut fruit

ROCCULI, PIETRO; PANARESE, VALENTINA; TYLEWICZ, URSZULA; SANTAGAPITA, PATRICIO R.; COCCI, EMILIANO; GÓMEZ GALINDO, FEDERICO; ROMANI, SANTINA; DALLA ROSA, MARCO

Avignon

Simposio; Euro-mediterranean Symposium for Fruit & Vegetable Processing; 2011

INRA/ University of Avignon

The aim of this research is to show the potentiality of isothermal calorimetry to study the metabolic response of different fresh-cut fruit tissue (kiwifruit, strawberry and cantaloupe) subjected to different processing (osmotic treatment) and storage conditions (modified atmosphere - MA - exposure or storage in syrup). This has been investigated in terms of heat production of endogenous (tissue metabolism during 12 h of analysis at 10 °C for kiwifruit and strawberry) and exogenous (microbial growth during 18 d of analysis at 10 °C for cantaloupe) biological processes. After osmotic dehydration in sucrose solution (61.5% w/v) at different treatment times (30, 60 and 180 min), kiwifruit pericarp tissue showed lower metabolic heat production compared with the fresh tissue, corroborating previous findings about the progressive cell death induced by osmotic dehydration. Isothermal calorimetry analysis on strawberry slices, performed under two different atmospheric conditions (synthetic air and MA: 79% N2O + 21% O2), seemed to validate, also for this fruit species, the inhibitory effect on metabolic activity of N2O. The analyses carried out on cantaloupe samples immersed in three different syrups with an increasing stabilizing effect (SS: sucrose syrup (20 °Brix); SS1: SS + 0.5% ascorbic acid + 0.5% citric acid (w/v); SS2: SS1+ 0.1% potassium sorbate (w/v)) revealed the potentiality of this technique, for the optimization of syrup formulation in order to increase the microbiological stability of fresh-cut fruit. These findings confirm that isothermal calorimetry provides a versatile tool for conducting fundamental metabolic studies on the effect of different processing operations on the quality and shelf life of fresh-cut fruit and vegetables, contributing to the necessary knowledge base for process development and optimisation in the industry as well as for predicting and ensuring quality and shelflife of this kind of products.