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This study aims to compare effects of sources levels of zinc on growth and carcass quality, some haematological and serological indices of juvenile beluga sturgeon, Huso huso (Linnaeus, 1758). A number of 315 juvenile beluga sturgeon (8.4±0.29) were fed in 21 500 lit fiberglass tanks (15 fish per tank) under 7 experimental diets including 1 control diet plus 6 diets containing zinc (mg per kg of diet) in two forms of mineral (zinc sulfate) (ZnSul₁₅, ZnSul_30, and ZnSul₆₀ treatments) and organic (chelated with methionine) (ZnMet_15, ZnMet₃₀, and ZnMet₆₀ treatments) with three replications per treatment for 12 weeks. The best values of final weight and feed conversion ratio were observed in the ZnMet₁₅ and ZnMet₆₀ treatments_. Red blood cells, hemoglobin, and hematocrit showed an incremental trend influenced by increased zinc supplement. Increased carcass protein in the ZnMet₃₀ treatment was significant compared to the control, ZnSul₁₅, and, ZnSul₃₀ treatments (P≤0.05). Reduced carcass lipid in the ZnSul₃₀ and ZnSul₆₀ treatments was significant compared to the other treatments (P≤0.05). Serum triglyceride and cholesterol decreased in the ZnMet treatments compared to the control treatment. Reduced serum glucose in the ZnMet₁₅ and ZnMet₆₀ treatments and also increased serum lysozyme in the ZnMet₃₀ and ZnMet₆₀ treatments were significant compared to the control treatment (P≤0.05). Results demonstrated that most of the indices had better performance in the ZnMet treatments comparted to the other treatments and are proposed as an optimal diet for juvenile beluga sturgeon.
 

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Gelatine is one colloidal protein that it used the most widely in the food, pharmaceutical, medical and military industry. Annually , considerable amounts of gelatine for different uses were transfered into the country. In other hand, the Caspian Sea is the rich sources of fishes such as Beluga sturgeon, carp, Caspian White fish and etc, that significant amounts of residue which is lost as waste that can be a good source to extract gelatine. In this study the effect of different extraction methods gelatine (I, II, III and IV) of beluga skin was examined. Results showed that the highest melting point, yeild and absolute viscosity gelatin extracted were observed in II, III and III methods, respectively. The gelatine viscosity decrease with increasing concentration of sodium hydroxide (method II and IV), and with smaller amounts of (Methods I and III), increases. Also, using the Arrhenius equation to determine the relation between viscosity gelatine and temperature were used, then activation energy calcuated in the range 16.31 to 32.66 kJ / mol respectively. Finally, using exponential and power models viscosity gelatine was fitted with Brix. Modeling results indicated that the exponential model was more accurate in predicting the gelatine absolute viscosity

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Caviar is one of the valuable and most popular fish products all over the world that are obtained from sturgeons. Nowadays, the wild resources of these fishes are diminished, therefore, to meet the demand for the product, farming sturgeons has been considered. The chemical composition and the amino acids profiles of the wild and farmed roe obtained from beluga (Huso huso) were compared and the results have indicated that the amount of glutamine, serine, alanine, methionine, and lysine in the wild roe were higher than the farmed one (P< 0.05). The total amino acids (TAAs) and the ratio of essential amino acids (EAAs) to TAAs and EAAs to non-essential amino acids (N-EAAs) in the samples from the wild and farmed roe were similar (P> 0.05). The protein efficiency ratio (PER) and chemical score in farmed and wild roe were also similar (P> 0.05). The results showed that the farmed roe was similar to the wild one based on chemical composition, chemical score, PER, EAAs/TAAs and EAAs/N-EAAs. According to the results, farmed roe can be a good substitution for wild beluga roe (Huso huso).

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The purpose of this study was to investigate the effect of microwave pretreatment on the degree of hydrolysis and antioxidant activity of Beluga (Huso huso) viscera protein hydrolysate. For this purpose, the samples were hydrolyzed after two conditions of pretreatment including no treatment with microwave or after ten minutes treatment with microwave (frequency 2450 Hz and temperature 90 °C), by alkalase enzyme with a concentration of 2%, temperature of 55°C and pH 8, and then the degree of hydrolysis and antioxidant activity of the produced samples were evaluated. According to the results, the degree of hydrolysis after microwave treatment was significantly higher than the sample without microwave treatment (p<0.05). Also, the sample produced after microwave treatment showed higher antioxidant activity (DPPH and ABTS radicals scavenging activity and Fe reduction capacity) compared to the control treatment (p<0.05). The IC₅₀ values ​​of this treatment in inhibiting DPPH and ABTS radicals scavenging activity were obtained as 1.25 mg/ml and 1.63 mg/ml, respectively, which was significantly lower than the control treatment (p<0.05). Also, in both samples, antioxidant activity increased significantly with increasing concentration (p<0.05). In general, it can be stated that 10 minutes of microwave pretreatment at 90 °C has a favorable effect on the properties of Beluga viscera protein hydrolysate which can indicate the applicability of this technology in the production process of fish protein hydrolysate.