Effect of temperature on the microbial flora of herring fillets stored in air or carbon dioxide

Molin, G. & Sxenstrom, I-M. 1984. Effect of temperature on the microbial flora of herring fillets stored in air or carbon dioxide. Journal of Applied Bacteriology56, 275–282. The microbial development on fillets of herring from the Baltic Sea was studied at temperatures from 0–15dC in air or 100% carbon dioxide (96–100% CO2). The shelf-life of the fillets, defined as the time for the ‘total aerobic count’ to reach 1 times 107 c.f.u./g increased with decreased temperature from 1 d at 15dC to 7 d at 0dC (air). The corresponding values in CO2 were 3 d and 33 d, respectively. The initial flora of the herring fillets was dominated by Alteromonas putrefaciens and Pseudo-monus spp. and so was the spoilage flora after storage in air (together 62–95% of the flora; ail temperatures). Alteromonas putrefaciens predominated slightly at 2dC to 15 C. while Pseudomonas spp. dominated at 0dC. The Pseudomonas flora was mainly split between Ps. fragi, Ps. fluorescens and a heterogenous group of unidentified Pseudomonas spp. The proportions were not influenced by temperature. In 100% CO2 at the time of spoilage the flora consisted of a significant number of Lactobacillus spp. Below 4dC the domination was almost complete while at 10dC and 15dC Enterobacteriaceae, Vibrionaceae and Alt. putrefaciens were also found. It was concluded that the microbiological shelf-life of herring fillets is improved by refrigeration storage in 100% CO2 but for good results the temperature should not exceed 2dC.