Biochemical composition of caviar as a tool to discriminate between aquaculture and wild origin

Abstract

Summary The over-exploitation of sturgeons for caviar production has led to drastic decreases of the commercially harvested sturgeon stocks. As a consequence, all sturgeon species were world-wide listed in Annex II or I of the CITES regulations. Since caviar trade needs to be controlled precise source (farmed vs wild) and species identification of the caviar are essential. Species discrimination is successfully performed by molecular genetic techniques. Whereas the origin of caviar either from wild stocks or from aquaculture cannot yet be differentiated using these techniques. As a consequence, the lack of an applicable technique for source identification complicates the control of black marketing of illegally produced sturgeon products. The determination of the chemical and biochemical composition of caviar, both of wild caught and farmed animals was attempted in this study to explore the potential of biochemical techniques for source identification. The results on size, protein and fat content, fatty acid (FA) composition of triglycerides (TG) and phospholipids (PL), as well as the concentrations of relevant heavy metals and chlorinated hydrocarbons from 38 samples of wild caught and 12 samples of farmed sturgeon were investigated. Significant differences with respect to the origin of the caviar were revealed in FA composition only. TG and PL contained more n-3 FAs, especially eicosapentaenoic (20:5 n-3) and docosahexaenoic acid (22:6 n-3) than n-6 FAs. Specific differences in the TG profile of wild caught and intensively farmed fish, depended on the feed sources utilized. It is therefore suggested to use specific FAs as additives to the formulated diets in order to provide the opportunity to ease the verification of the farm origin in traded sturgeon commodities.