Bacterial inactivation and quality changes in fresh-cut avocado treated with intense light pulses

摘要

This study investigated the impact of intense light pulses (ILP) on inactivation of Listeria innocua and Escherichia coli as well as quality changes in fresh-cut avocado. Cylinders of avocado inoculated with L. innocua or E. coli were placed in plastic trays, which were sealed with a 64-μm-thick polypropylene film (oxygen permeability of 110 cm3 O2 m−2 bar−1 day−1 at 23 °C and 0% RH) and subjected to 15 or 30 pulses at fluencies of 0.4 J/cm2 per pulse and then stored for 15 days at 5 °C. In addition to L. innocua and E. coli counts, the headspace atmosphere, pH, colour and firmness were measured. The growth of E. coli and L. innocua was more effectively inhibited when increasing treatment intensity. Hence, significant inactivation was obtained in samples treated with 15 and 30 pulses for L. innocua (2.61 and 2.97 log CFU/g, respectively) and E. coli (2.90 and 3.33 log CFU/g, respectively) just after processing. Oxygen concentrations were significantly reduced, whereas CO2 and ethanol concentrations increased due to product respiration; however, ethylene production was decreased by the effect of ILP treatments. The use of 30 pulses affected the colour and firmness of fresh-cut avocado, causing browning and softening.