Effects of spray programs in vineyard and different type of sun-drying system on formation of ochratoxin A on raisins

摘要

Turkey is the biggest raisin producer and exporter country in the world. One of the major problems on raisins is the mycotoxin formation, especially ochratoxin A (OTA), produced by two main genera of fungi {Aspergillus and PenicilHum). In this study, effects of preharvest spray programs in vineyards and different types of sun-drying systems were examined on formation of OTA on raisins in Manisa, Sangol, Turkey. Considering the Aspergillus spp. contamination on grapes, a spraying program was established.In the same vineyard a non-spraying parcel was kept as a control. The spraying program, farmer's program and control were compared in three separate parcels. The spraying program was started after the last fungicide applications for powdery mildew in the vineyard. Before harvest the disease development was evaluated in bunches in vineyard. After harvest, grapes were sun dried on concrete surface and soil ground. Raisins were packed into the commercial sacks and polyethylene bags. Later they were separated in two parts and stored at room temperature and 2.5°C for 8 months. OTA analyses were carried out on fresh berries and after drying on raisins. It was also repeated after two months of storage of raisins at different storage conditions. The microbial load was tested on raisins during storage. The greatest microbial loads by Aspergillus spp. was found on raisin dried on soil ground, while the lowest microbial load was obtained from raisins dried on concrete surface and kept in cold storage. Preharvest fungicides applications reduced the growth of Aspergillus spp. population. After two months of storage OTA in raisins was not detected in all applications.