Organoleptic, physicochemical and microbiological properties of caviar at retail trade

To investigate the organoleptic, physicochemical and microbiological quality of caviar, fifty caviar samples from various fresh- and seawater fish species were obtained from retail markets and tested. Only 36 % of the samples were without organoleptic deviations. 46 % of the samples showed cell counts of mesophilic aerobic bacteria of >2 log(10) CFU/g. Of these, the majority (n = 12) showed cell counts of 3-4 log(10) CFU/g. Two samples exhibited high cell counts of >6 log(10) CFU/g. Lactic acid bacteria were found in 20 % of the samples, reaching up to 5.8 log(10) CFU/g. Yeasts were detected in 10 % of the samples and moulds were present in one sample. For coliforms, 4 % of the samples showed growth with counts of 2.3 log(10) CFU/g and 3.4 log(10) CFU/g respectively. However, E. coli was not detectable. One sample contained 3.43 log(10) CFU/g coagulase positive staphylococci and 5 log(10) CFU/g pseudomonads. Mycobacterium aubagnense, a potential zoonotic pathogen, was detected within four samples. Neither lower pH, lower water activity, higher salt concentrations nor pasteurization influenced the microbiological quality of these products significantly. Taken together, microbiological quality of most caviar samples was acceptable. Nonetheless, single samples showed high microbiological loads. Many caviar samples exhibited organoleptic deviations. To limit microbiological growth and subsequent changes in organoleptic properties, a continuous cooling of these products is necessary. The importance of potentially pathogenic Mycobacterium spp. (incl. Mycobacterium aubagnense) in caviar must be evaluated in future studies.