In the present study, changes in the microbiological quality of caviar produced from the eggs of Rainbow trout (Oncorhynchus mykiss Walbaum, 1792) was investigated during vacuum packaged storage at 4 + 1 ºC. Microbiological analysis of the samples were carried out during production, and on days 0, 7, 14, 21, 28, 42, 56, 70, 84 and in every 30 days until day 324.

The average numbers of aerobic mesophilic bacteria of the eggs was 2.05 log10 cfu/g. This level exhibited changes during storage and was found as 2.78 log10 cfu/g by the end of storage (day 324). These changes were statistically significant (P<0.05). The level of coliform bacteria was less than 0.48 log₁₀ MPN/g on all days. E. coli was not detected in any samples. The numbers of Staphylococcus-Micrococcus was 1.25 log₁₀ cfu/g at the beginning of the study and continuously increased as the storage period progressed. However, such increases were not significant (P>0.05). Staphylococcus aureus was not detected in any samples analyzed. The numbers of the yeast-mold were 0.97 log10 cfu/g in eggs and showed some changes that were not significant (P>0.05) until day 56. After day 56, the numbers of the yeast-mold dropped below detectable level (<1 log₁₀ cfu/g).

As a result, no statistically significant differences in the microbiological quality of vacuum packaged caviar were observed during the 324 day storage.