Psychrophilic and Mesophilic Fungi in Fruit-Filled Pastries

Abstract

Surveys of the mold flora of frozen blueberry and cherry pastries were undertaken. Molds were enumerated by preparing pour plates of the blended product and incubating the plates at 0, 5, 10, and 20 C. In this manner, the total fungal content of the product could be ascertained from the 10 and 20 C plates, and the psychrophilic fungal population was represented by those fungi which grew at 0 and 5 C. The pastry portion, or crust, of the blueberry material was sampled separately from the filling portion. Certain differences in fungal flora were apparent. Aureobasidium pullulans was the dominant fungus in crust at all temperatures of isolation. However, Penicillium thomii proved to be the most common mesophilic fungus in the filling portion, and A. pullulans was the most common psychrophile in the filling. Aspergilli were quite common in the crust, but, in general, were absent from the fruit filling. Cherry pastries had a much smaller total fungal flora than did the blueberry product. However, A. pullulans again was the most prevalent fungus in cherry pastries at all temperatures of isolation. Certain differences in fungal flora were apparent in the two fruit products. Phoma spp. were almost completely absent in blueberries, but represented the second most common fungus in cherry pastries. Blueberry filling had 440 psychrophilic fungi per gram of sample (at 0 C), blueberry crust had 65 per gram, and cherry pastries had 77 per gram.