Influence of ripening stage on quality parameters and metabolic behaviour of fresh-cut kiwifruit slices during accelerated storage

The aim of this work was to evaluate the influence of the ripening stage on fresh-cut kiwifruit tissues in terms of quality and tissue metabolism, during accelerated storage (AS) in controlled conditions. For this purpose three different ripening stages were selected, corresponding to about 11, 13 and 15 °Brix. For each ripening stage the fruits were peeled and cut into 1 cm thick slices and stored in climatic chambers at 10 °C, 90% RH, for 3 days. During storage, quality indices as soluble solid contents, titrable acidity, colour and texture were monitored. Metabolic assessment was carried out evaluating the endogenous metabolic heat using isothermal calorimetry, and monitoring O2 consumption and CO2 production simultaneously. Differences were found in the evolution of the quality indexes during storage; in particular kiwifruit at the lowest ripening stage showed the slowest quality degradation, both in terms of softening and visual quality modifications. Metabolic heat production results were different at the different ripening levels investigated, evidencing a strict connection between the physiological state of the tissue and the entity of its wounding response.