Populations and identification of fungi causing postharvest molds, on pineapple peduncles in two regions in Costa Rica

Pineapple peduncle mold is an important postharvest problem in Costa Rica and it causes fruit rejection. The objective of this study was to identify and quantify the most important fungi in different postharvest phases. Monthly samplings were performed during one production year in 2 regions of Costa Rica. The main genera of fungi were identified and characterized at the molecular level. The colony forming units (CFU) were determined in disinfection water, wax, cooling rooms air and in the peel and peduncle of fruits before (NP) and after (P) processing with the common postharvest treatments of the farms. Fruits were stored in cooling rooms during 22 days and at the end incidence and severity of peduncle molds were evaluated. During the year, changes in fungi populations were observed in all postharvest phases and in the fruits, with higher populations in wax than in disinfection water. Fungi population and molds were higher in the peduncle of NP fruits as compared with P fruits, coincident with larger mold populations at the end of storage. Fungi recovered in the cooling rooms air could also be a source for peduncle molds development. Penicillium purpureogenum, P. diversum and Penicllium sp., were the main fungi identified, with an in vitro high sporulation rate and growing in the peduncle. Moreover, different commercial practices, such as waxing and cooling, where spores were captured, can enhance the peduncle molds development, so it is considered important the cleaning of cooling rooms, as well as developing mechanisms to avoid accumulation in wax of important populations of microorganisms.