BACTERIOLOGY OF SPOILAGE OF FISH MUSCLE. I. STERILE PRESS JUICE AS A SUITABLE EXPERIMENTAL MEDIUM.

A sterile raw fish muscle press juice, diluted 1:4 with saline, has been prepared. This dilution greatly facilitated Seitz filtration and affected the spoilage properties of the medium only negligibly. At 5.5 C, the spoilage pattern of naturally contaminated diluted juice was almost identical to that of naturally contaminated fillets. This was shown by comparing the quantitative and qualitative aspects of the bacterial flora on the two substrates and by measuring the production of volatile reducing substances (VRS) and of trimethylamine (TMA). With the sterile raw muscle press juice, some preliminary data showed that individual members of the genera Achromobacter and Pseudomonas differ markedly in their spoilage capabilities: some grew but did not produce spoilage detectable either organoleptically or chemically; others gave rise to strong off odors and to high levels of VRS and TMA.