Abstract
To estimate the risk of microbial hazard in foods packaged in hermetically sealed containers, forty-nine such foods, purchased at markets in Fukuoka, were tested for pH and water activity. The pH and water activity of eighteen foods were in excess of 4.6 and 0.94, respectively. For five out of the eighteen foods the sterilizing or heating method was not indicated. Bacterial contamination of food packaged in hermetically sealed containers produced in Fukuoka was examined from the perspective of food hygiene. Five types of foods designated A to E, each type consisting of 15 samples (3lots×5samples), were produced in Fukuoka. In each sample, aerobic bacteria, aerobic spore-formers, growth of clostridia organisms, mouse lethality with botulinum toxin, water activity and pH were examined. Bacteria grown on standard agar medium were used for homologous search for 16S rDNA base sequence by blast research. The pH and water activity of four food types (A, B, C and D) were in excess of 4.6 and 0.94, respectively. In food A, all 15 samples demonstrated growth of bacteria on standard agar plates, and 8 samples on clostridia medium. Bacteria detected on standard agar medium were identified as aerobic spore-forming bacteria (Bacillus, Paenibacillus, Virgibacillus, Brevibacillus), Pseudomonas, Staphylococcus, Kocuria, Methylobacterium, and Microbacterium. In food C, each sample in three lots was contaminated with the organisms of Genus Bacillus (B. subtilis, B. firmus, or B. subtilis), respectively. In food E, the water activity of all 15 samples was below 0.85. All of them, however, were also contaminated with the bacteria of Genus Bacillus (B. subtilis, B. simplex, or Bacillus spp.).
A label saying that “the contents were heated under pressure to sterilize the food after packaging in a hermetically sealed container” was put on two types of foods, but one of them was contaminated with bacteria. No sterilization methods were described in the labels of the other three food types, and two of them demonstrated bacterial contamination. In order to prevent food poisoning, the makers of these foods should describe the proper conditions for sterilization. In cases of insufficient sterilization, the foods must be kept under cool conditions and the period of safe consumption should be shown in a label under the Food Hygiene Act.
