Effect of sodium alginate coating enriched with horsemint essential oil (HEO) on the quality of bighead carp (Aristichthys nobilis) fillets at refrigeration temperature (4 ± 1°C) was studied. Bighead carp fillets were coated with neat sodium alginate (SA) and sodium alginate containing 0.5 and 1% v/v of HEO and their quality changes in terms of total volatile basic nitrogen (TVB-N), peroxide value (PV), thiobarbituric acid (TBA), and microbial counts were investigated. SA coating enriched with the essential oil could reduce the spoilage of the fillets and extend their shelf-life. Samples treated with SA-containing HEO showed significantly (P < 0.05) lower TVB-N content and lipid oxidation, as reflected by lower PV, FFA and TBA values during the storage period compared with the SA and control. The treatment also reduced the degree of microbial deterioration of the fillets (about 1.5 log10 CFU/g) more efficiently than the SA.

No abstract

Taurine is one of the most studied amino acids in aquaculture over the last decade. This study was conducted to investigate the taurine requirements in terms of growth, immune system, antioxidant enzyme activities and stress response of beluga (Huso huso) (209.1 ± 23 g) in both fresh water (FW) and brackish water (BW: 15 ppt). Twelve experimental tanks with six taurine levels (2.1 g/kg_21.8 g/kg), for FW (Tau2.1, Tau4.3, Tau7.1, Tau12.3, Tau16.7 and Tau21.8) and BW (BwTau2.1, BwTau4.3, BwTau7.1, BwTau12.3, BwTau16.7, and BwTau21.8), were designed to feed and farm fish for eight weeks. Generally, fish farmed in BW had better growth and immune response performance compared with FW. The quadratic relations for pooled data determined taurine requirements in terms of weight gain (12.1 g/kg), lysozyme (13.5 g/kg), IgM (12.7 g/kg) and osmolality (15.1 g/kg) (p<0.05). Furthermore, taurine requirements to obtain the minimum cortisol before and after stress were 10.4 g/kg and 14.3 g/ kg, respectively. When we exposed fish to high stock density stress (12 kg/m 3 for 4 hours), those fed dietary 16.7 and 21.8 g/kg had more stable glucose, cortisol and lactate before and after stress in both FW and BW. In conclusion, beluga fed diets with 12.3 g/kg and 16.7 g/kg taurine in both FW and BW groups had the best performance regarding growth and health status, respectively.

Fish peptone was produced using enzymatic hydrolysis of silver carp filleting by-products by alcalase and trypsin. Also, the efficiency of the hydrolysates as a nitrogen source in Staphylococcus aureus medium was compared with commercial TSB. The results indicated that the protein hydrolysate from alcalase and trypsin had high protein content (92.92%, 91.53 respectively), and degree of hydrolysis (4.94%, 4.6% respectively).The results showed that silver carp filleting waste can be an efficient source for fish peptone production as a nitrogen source for S. aureus medium. However, the type of the used proteolytic enzyme considerably affected the performance of the resulting peptone despite the same DH. Fish peptone produced by alcalese performed significantly (P < 0.05) better than commercial TSB as a media for the bacteria while the performance of the trypsin peptone was not as good as the commercial medium.

The effect of fennel extract on the quality of silver carp (Hypophthalmicthys molitrix) fillets, and the possible efficacy of liposomal encapsulation in the improvement of its antimicrobial and antioxidant activity during chilled storage (4 + 1°C) of the fillets were examined over a period of 15 days. Silver carp fillets were treated with pure fennel extract (0.3% and 0.5% w/v) and liposomal encapsulated fennel extract (0.3% and 0.5% w/v), and their quality changes in terms of total volatile basic nitrogen (TVB‐N), peroxide value (PV), thiobarbituric acid (TBA), microbial counts, and sensory properties were investigated. Fennel extract could retard the deterioration of silver carp fillets, as reflected in lower TVB‐N, PV and TBA value. Moreover, the efficacy of fennel extract was improved when it was encapsulated into liposome. Silver carp fillets treated with the encapsulated fennel extract showed the lowest amount of lipid oxidation and microbial deterioration during the storage period compared with the control and pure extract treatments. Sensory evaluation revealed that shelf life of silver carp fillet was longest for samples treated with encapsulated fennel extract at 0.5% (15 days), as compared to the control (6 days) (P < 0.05).