Direct plating: A method for detecting fungal contamination in paperboard cartons

Contamination of refrigerated juice products in gable-top cartons can occur by filamentous fungi that are present in the paperboard. A method was deve loped to assay the mycoflora of paperboard carton material used in beverage packaging. This method involved direct plating on an agar surface of 1 cm( 2) carton pieces rather than disintegration of carton material in a blender prior to plating. When compared to the standard disintegration method trad itionally used for monitoring contamination of paperboard, the new method i s less cumbersome, more efficient, and reduces opportunities for contaminat ion. The number of colonies produced by the direct plating method was great er than or equal to the modified standard disintegration method. Direct pla ting also resulted in a larger number of different genera isolated.