Inhibition of Microbial Growth in English Sole ( Parophrys retulus ) ¹

The influence of potassium sorbate on growth of microorganisms in seafood was tested by treating English sole ( Parophrys retulus ) homogenate with 0, 0.1 and 1.0% potassium sorbate. Viable counts during 1.1-C storage revealed that 0.1% potassium sorbate delayed the onset of logarithmic growth of bacteria for 1 day compared to no delay for the untreated control. The generation time of 1.7 days and a maximum growth level of 10⁹ cells per g were unchanged by the presence of 0.1% potassium sorbate. The 1.0% sorbate treatment extended the lag period to 6 days. The generation time was increased to 2.1 days and the maximum level of growth reached was 10⁷ cells per g on the 14th day. Tests of the microbial flora of the fish revealed that Pseudomonas spp., which comprised 17.1 %of the total at 0 day, increased to 96.0% of the microbial population in 14 days at 1.1 C for the untreated sample. During the same period the Pseudomonas population reached 100% for the 0.1% sorbate-treated sample, and to 98.2% for the 1.0% sorbate-treated sample. Potassium sorbate at the concentrations employed, therefore, did not seem to alter the typical microbial spoilage pattern.