Influence of storage period and shelf-life on the incidence of chilling injury and microbial load in "Angeleno" and "Larry Ann" plums

Abstract

Refrigeration is the most widely used post-harvest technology for increasing commercial life (shelf-life) of plums after harvest. Nevertheless, low-temperature conservation is limited by chilling injury (CI), leading to rejection by consumers. The objective of the present work was to characterize biotic and non-biotic chilling injures that lead to quality loss in plums during post-harvest storage. Larry Ann and Angeleno plums were stored at 1.0±0.5°C and 90.0±2.0% RH for 4 and 8 weeks and after this period the plums were stored either 3 or 6 days at 20ºC for evaluating changes in their shelf-life. Pulp firmness, post-harvest losses, presence of chilling injuries and the count of mesophilic microorganisms, molds and yeasts were determined after harvest and after storage plus shelf-life. In general, a drastic decrease in the growth of bacteria, mold and yeast during post-harvest storage at 1ºC was observed, following an increased microbial growth during shelf-life storage. Sensitivity to low temperature was cultivar-dependent. Larry Ann plums showed higher pulp firmness reduction and lower impact of CI than Angeleno, with an increased microbial spoilage. Plums that presented cold-damaged or physiologically compromised tissues suffered from faster decomposition and provided a better substrate for microbial growth than non-damaged plums.