Effect of carbon dioxide(CO2) atmosphere on bacterial counts and total volatile basic-nitrogen(TVB-N) of the unfrozen and frozen(-20℃, 7days)-thawed pink shrimps Pandalus borealis and hardback shrimps Trachypenaeus curviostris during 3 days strage at 10℃ were examined. CO2 suppressed the growth of aerobic bacteria in unfrozen shrimps. However, the lactic-acid bacteria were promoted and the number of anaerobic bacteria was not affected. In the case of frozen thawed shrimps, the anti-bacterial effect was more significant. Furthermore, CO2 suppressed the growth of anaerobic bacteria and lactic-acid bacteria in the thawed shrimps. Increasing of TVB-N in the shrimps was suppressed by both of the CO2 and freezing treatment. These results indicate that the useful preservative aspects of CO2 atomosphere packaging are affected significantly by the freezing.

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