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During the 1938 blueberry season the attention of the Research Laboratory of the National Canners Association was called to the occurrence of small plaques of mold in No. 10 cans of blueberries. These occurred only on the surface and in enamel-lined cans. Mold could not be found below the surface layer, nor did it occur in plain cans. The vacuum of both plain and enamel-lined cans was in the range of 12 to 15 inches.Because of the protection against spoilage by spore-forming bacteria afforded by the high acidity of blueberries ( p H 3.4 t o 3.7) it is only necessary to heat this product sufficiently to destroy yeasts, molds, and non-sporing, acid-tolerant bacteria. I n the factory in which this occurrence was noted the blueberries were filled into the cans at a temperature approaching 93.3"C. (ZOOOF.) j the cans were sealed, inverted, and air cooled. This procedure results in a good vacunm in the can after cooling and is adequate to destroy organisms of low heat resistance. The presence of growth indicated therefore a mold of more than usual resistance to heat. I n plain cans the small amount of oxygen remaining in the can after sealing is quickly taken up through oxidation of the exposed metal surface. I n enamel-lined cans oxidation is delayed by the protective coating on the metal. The small amount of growth occurring only in enamel-lined cans suggested, therefore, that the mold was a facultatively anaerobic type which through its metabolic activity soon reduced the oxygen level to a limiting concedtration.Because of the apparent resistance to heat and capability of growth in low oxygen concentration it was felt that the organism was of sufficient importance and interest t o justify investigation.Isolations were readily made on plates of Difco Wort agar and on blueberry juice agar. Two strains were isolated, one of which produced ascospores, the other sclerotia. These were submitted to Dr. Charles Thom, of the United States Department of Agriculture, and we are informed by him that they appear to be strains of a single undescribed species of Penicillium. 69

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