Microbiological and chemical changes during the industrial soft-drying process of 'Migaki-Nishin' herring [Clupea pallasii]
2007
Nakagawa, R.(Hokkaido. Food Processing Research Center, Ebetsu (Japan)) | Noto, H. | Yasokawa, D. | Kamatani, T.
It has been noted that soft-dried 'Migaki-Nishin' herring does not rot despite containing large numbers of bacteria. Microbiological and chemical changes during the industrial drying process were investigated. The number of bacteria increased during drying, reaching 1.3 x 10E8 cfu/g on the final day, which was four days from the start of drying. The enterobacteria count obtained after drying was 2.3 x 10E7 cfu/g. Thirty colonies on standard plate count agar medium at five different stages were identified on the basis of the nucleotide sequence of the 16S rRNA gene. Identification showed that before drying the majority of bacteria belonged to the genera Streptococcus, Acinetobacter and Dermabacter, but after drying, the majority were Staphylococcus (about 70%). Specific multiplex PCR assays were used to determine the species of Staphylococcus isolated; the predominant species was found to be S. saprophyticus. Next, the amounts of amino acids and acetic acid present were measured to clarify the effect of microbes such as Staphylococcus in drying. The individual amounts differed among samples, but a slight effect on the formation of these chemicals was observed. It is thought that Staphylococcus may contribute to the quality of soft-dried 'Migaki-Nishin' by controlling microorganism growth and preventing rot.
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