KINETIC MODELLING OF MICROBIAL SUPPRESSION, TRANSPIRATION AND SHELF LIFE OF SWEET CHERRY TREATED WITH COMBINED UV-C RADIATION AND ULTRASOUND

Combined ultraviolet-C (UV-C) radiation and ultrasound (US) is a promising non-thermal postharvest treatment, but quantitative descriptions of how the treatment dose translates into shelf life are scarce. This study reviews the individual and combined use of both technologies on fresh produce and presents a secondary kinetic analysis of a storage experiment in which sweet cherries (Prunus avium L.) received 0, 1, 3 or 5 kJ m-2 UV-C followed by 35 kHz ultrasound and were stored at 4 °C for 20 days. Five competing models of total viable count (TVC) were ranked by the corrected Akaike information criterion. The best model (Akaike weight 0.95) combined a first-order decline of the viable population with linear regrowth and a suppression amplitude that rose by 0.67 log per kJ m-2 plus a dose-independent step of 0.52 log shared by all treated groups. Leave-one-group-out validation predicted withheld groups with errors of 0.08–0.17 log CFU g-1. Each additional kJ m-2 delayed regrowth by about 5.0 days, independent of the reference level chosen. The apparent transpiration coefficient fell from 932 to 274 mg kg-1 s-1 MPa-1, and a dry-matter balance showed that water loss explains only 23–68% of the higher soluble-solids content of control fruit. A desirability analysis indicated that the preferred dose scales with lamp irradiance and is limited by exposure time rather than by microbial response.