| Sturgeon caviar as one of the world delicacies, is the main product in sturgeon aquaculture industry. With the fast development of sturgeon aquaculture in china,investigation on storage quality of farmed sturgeon caviar has great significance for the caviar aquaculture. The effects during 0℃cold storage of sturgeon caviar,sturgeon caviar with potassium and sturgeon caviar with borax were respectively investigated by analyzing the changes in Volatile components, amino acid composition, volatile basic nitrogen values, TBA values and total bacterial count. In addition, the microorganisms make great influence to storage quality and taste of sturgeon caviar.In order to find the best preservative and condition of storage,the changes of microflora on vacuum packing sturgeon caviar were studied during storage, which also provide reference and basis in the study of functional bacteria adding to sturgeon sauce for greater flavor fermentation.The results obtained in this paper are as follows:(1) The most content of amino acid in sturgeon caviar were glutamic acid and asparic acid,which have umami characteristics.Adding potassium sorbate and borax reduced these two kinds of amino acids and total amino acids in different degree,and contrary to the phenomenon that at the early stage the effect was more obvious in potassium potassium group, it was more obvious in borax group during anaphase storage.During 0℃ storage, the TVB-N value and TBA value of sturgeon caviar increased gradually with the extension of time.The TVB-N results showed the single preservative had a great effect in inhibiting protein hydrolysis and keep the protein nutrition. The TBA value results showed that sturgeon caviar could keep 4 months without odor-causing at 0℃ temperature, while potassium sorbate and borax groupcould keep 7 months, and the inhibitory effects on lipid oxidation of borax is better than potassium sorbate.The volatile compounds of sturgeon caviar was mainly aldehydes, ketones, alcohols, acids, esters and hydrocarbons, among which aldehydes made the most contribution to the sturgeon caviar flavour. Borax reduced the production of aldehydes because of the inhibition to lipid oxidation, therefore,adding borax could weakened the smell of fat oxidation and fishy in sturgeon caviar.The total bacterial counts showed borax and potassium sorbate had a great bacteriostatic effect on caviar and the effect of borax is more significant than potassium sorbate.(2) The change of bacterial flora on vacuum packing sturgeon caviar was studied during 0℃storage. The bacterial diversity showed a trend of first increasing and then decreasing, and the bacterial species were most abundant in the second month.Microflora of sturgeon caviar was relatively single, and the dominant bacterias mainly included Pseudomonas, Shewanella, bacillus and Psychrobacter. These bacterias were often reported as the common dominant bacteria and spoilage bacteria in aquatic products,which had great impact in quality of sturgeon caviar during storage. Bacillus cereus were identified as the dominant bacteria,which not only was a kind of pathogenic bacteria in food, but also made the fermentation food spoilage. In addition,a comparison of the group without any preservative,the group of adding potassium sorbate group and the group of adding borax indicated that the inhibitory effect of potassium sorbate and borax on Pseudomonas was extremely sligh.Potassium sorbate and borax had significant inhibition on Shewanella and bacillus.(3) The staphylococcus and yeast in the fermentation period of sturgeon caviar have been isolated and dentified as S.xylosus, S. Saprophyticus, S. Equorum,D.hansenii,R.mucilaginosa, C. Zeylanoides and Y. Lipolytica. The result showed S.xylosus and D.hansenii were the dominant staphylococcus and yeast, which were commonly used as ferment in the production of fermented food. Therefore, it can been considered to add Staphylococcus.xylosus and Debaryomyces.hanseniin in the processing of sturgeon caviar in order to improve the sensory quality. |
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