Molds Associated with Olive Fruits Infested with Olive Fruit Fly (Bactrocera oleae) and their Effects on Oil Quality

Olive is the most widely grown fruit tree in Jordan; it is annually attacked by the olive fruit fly, Bactrocera oleae (Rossi), whose larvae usually cause great economic losses in fruit yield. Alternaria solani, Aspergillus niger, Cladosporium herbarum, Fusarium solani, Penicillium digitatum, P. italicum and Rhizopus stolonifer were found associated with the fly infestation with a sample frequency ranging from 6.7-33.3%. Penicillium digitatum was the most dominant species. All molds were vulnerable for a hot water treatment at 50 and 70°C as indicated by their low spore germination and colonyforming unit except for P. digitatum and P. italicum which were the most heat-tolerant. When the olive oil was inoculated with pure cultures of these molds, the mold fungi were able to colonize olive oil. Rhizopus stolonifer was the greatest colonizer and besides Alternaria solani, both had obviously reduced the oil peroxide value over the control without greatly affecting the oil free fatty acid content.