Quality Changes Of Sturgeon Caviar During Low Temperature Storage And Source Of Microorganism Contamination In Processing

Sturgeon caviar, as a kind of instant sea food, is rich in both nutritional and economic value. However, caviar is perishable due to the lack of heat treatment, sterilization process or additives. Spoilage of caviar brought great loss to industry. Thus the quality changes and source of contamination are of critical role for shelf life elongation and spoilage reduction.In this paper, the changes of microb and some physi-chemical indicators of sturgeon caviar during storage and processing process were systematically investigated, also the main type of microbe in caviar was determined. First, changes of microorganism number and physi-chemical properties of sturgeon caviar was evaluated during a storage of 0-9 months at-3℃. Results showed that the numbers of total plate counting(TPC) and Pseudomonas displayed a significant upward trend with storage time, with a significant increase after 3 months. Lactic acid bacteria and yeast could be detected after storage for 6 and 9 months. The total volatile basic nitrogen(TVB-N) and acidity value also showed a significant increase after storage for 1 and 3 months, respectively. Moreover, the content of polyunsaturated fatty acid decreased significantly, but the monounsaturated fatty acid increased obviously. Pseudomonas might not be the dominant bacteria, by comparing with the number of TPC. Further microbe detection showed that Psychrobacter might be the dominant bacteria in caviar. Microbe detection in spoilage samples showed that yeast is likely to play a great impact on the quality of sturgeon caviar during low temperture storage. The main dominant bacterial type, characterized by 23and16s-rRNA sequence analysis, was Debaryomyces hansenii and Psychrobacter.During processing, draining(rubbing and washing egg) could effectively reduce the microbe number in cavia. And the salting process was contaminated seriously. The hands of people who was in charge of salting, electronic scale, and scraper blade were found contaminated by microbe seriously. So, washing and sterizing hands, sterilization of tools and equipment, reinforcing the aseptic technique and awareness of workers might be key to reduce the initial microbial biomass in caviar.Above all, the above results might provide new data for quality control during processing and storage of caviar, and so for shelf life extension of caviar.