Yeasts and bacteria associated with pineapple fruit during postharvest handling

Abstract

Fungi are common microorganisms causing peduncle moulds in pineapple fruits, but there is a lack of information about other microorganisms colonizing pineapples. Yeasts and bacteria are among the main microorganisms recovered from different fruits, but there is not enough information about their role in pineapple fruit. The objective of this research was to determine and quantify the frequency and populations of yeasts and bacteria associated with 'MD-2' (“Gold Extra Sweet”) pineapple fruits in postharvest. Twelve monthly samplings were performed in two packing houses in Costa Rica. The colony forming units (CFU log10) of yeasts and bacteria (Y+B) were determined in fruit peel and peduncle, before (WP) and after commercial processing (P), and in both WP and P fruits stored 19 days at 7°C + 3 days at 18°C. Molecular characterization analysing ITS1 and ITS2 regions and frequency of the main recovered yeast was carried out. Populations of Y+B were greater in WP than in P fruits throughout the year in both packing houses, with values between 0.5 and 4.6 CFU mL-1 in WP peduncles, and between 0 and 2.7 CFU mL-1 in P peduncles. In peels, populations were similar between P and WP fruits with values between 0.7 and 5.6 CFU mL-1. At the end of storage, populations of Y+B reached a maximum of 6.8 CFU mL-1 in WP peduncles and of 5.8 CFU mL-1 in P peels. Wickerhamomyces anomalus was the most frequent yeast isolated with a range of 20-100%, and it has been reported as a potential biocontrol microorganism in different crops. More research is needed to identify the role of yeasts and bacteria in pineapple fruits, especially the potential of W. anomalus as a biocontrol agent that could be introduced as part of an integrated program for management of pineapple peduncle moulds.