JOURNAL OF FISHERIES SCIENCE AND TECHNOLOGY (JFST)
Year:2015 | Volume:4 | Issue:3|Papers Count:11

The effect of ice-storage duration (0, 3, 6, 9, 12, and 15 days) of silver carp (Hypophthalmichthys molitrix) on qualitative properties of its surimi powder was assessed by analyzing proximate composition, color changes, density, oil adsorptioncapacity, protein solubility, emulsifying capacity, emulsion stability, gel form ingability, and thiobarbituric acid. Increase in ice-storage duration increased the densityand thiobarbituric acid of surimi powder (p<0.05); proximate composition, color indices, protein solubility, oil adsorption and gel forming decreased significantly (p<0.05); emulsifying capacity and emulsion stability decreased with storage duration, although no regular trends were detected (p<0.05). The present study indicated that long-term ice-storage of silver carp led to reduction of qualitative properties of the surimi powder.

The effect of the Primalac probiotic at four levels of 0, 0.05, 0.1 and 0.15% on growth performance, blood biochemical parameters, survival and resistance to salinity stress in common carp fingerlings (2.67±0.117 g) was assessed for a period of 45 days. Primalac enhanced growth performance and significantly decreased the FCR (p<0.05). Primalac also decreased the glucose levels and increased the to talprotein level, but the differences among treatments were not significant (p>0.05).Primalac significantly decreased the cholesterol levels (p<0.05). Salinity stress test was carried out after 45 days of feeding. Blood samples were taken four times after stress (first, third, fifth and seventh days) to evaluate hematocrit levels. On the firstday, the hematocrit levels increased significantly in all groups (p<0.05), but it decreased gradually in all groups after the third day. Before and after the stress, no differences were observed for survival rate among the treatments (p>0.05). These results indicate that addition of Primalac to fish diet exerted positive effects on growth, biochemical indices and reduce stress in common carp.

Chemical and physical properties of mince and surimi prepared from common carp were compared during 3 months of frozen storage. After preparation of mincedmeat, both unwashed mince and surimi were put in zip-lock bags and stored at -18oC for a period of 3 months. No significant changes (p>0.05) in protein and totalfat in both treatments were observed during different periods of storage. Peroxidevalue (PV) increased in the unwashed mince significantly whereas in surimi it increased only at the end of storage period. TBA and TVB-N values in surimit reatment were lower than the unwashed mince after three months storage. Regarding the TPA results for the unwashed mince, a decreasing trend was recorded in several physical properties such as hardness, cohesiveness, elasticity, chewiness and gumminess, whereas these parameters remained nearly constant for the surimiafter three months of storage. In conclusion, surimi from common carp couldpreserve its quality characteristics during frozen storage.

Protein hydrolysate (PH) from viscera of cultured Siberian sturgeon (Acipenser baerii) was produced. To optimize the production conditions, Response Surface Method (RSM) was employed to examine the effects of three different operating conditions, including time, pH, and enzymatic concentration (Alcalase) on the degree of hydrolysis. The mathematical model showed acceptable fitness of the experimental data as R2 equaled 0.97, which indicated that major part of the variability within the range of values could be explained by the model. The results showed that the highest degree of hydrolysis (58.21%) was related to the treatment which happened at the enzymatic concentration of 2%, 60 minutes time, and pH=8. Treatment under hydrolysis condition (i.e., E/S=2%, Time=45 min, and pH=8.5) had the highest protein content (42.37g/l), which was used as an alternative to commercial peptone medium (Triptic soy broth) to assess the growth of Salmonella typhi bacteria from 0 to 48 hours. Although there was an upwardtrend in growth rate of S. typhi both in control and No.15 (Alcalase) treatments, the log growth of control treatment was found to be better than that of Alcalasetreatment. However, there existed no significant difference between the twotreatments.

In this work, the paste of microalga, Tetraselmis suecica, was produced and the effects of vitamin C and E on its food value and shelf life improvement during eight weeks of storage in refrigerator (4oC) was investigated. The microalga was initially mass grown up to logarithmic phase in standard convey medium, then concentrated by cream skimmer centrifugation method. The obtained algal paste was treated by adding vitamins C, E and their mixture (all 0.1% weight/weight), and refrigerated for 8 weeks. The density of algal cells was1.38109 cells/ml and the production yield was about 1.7 gr/l. The cell viability in vit E-treated pastes (39/99±2/1%) was higher than the control group (p>0.05), indicating the positive effect of the preservatives. The proximate analysis showed that the control group had the lowest moisture (86.8 %), the vit C-treated group had the highest protein (36.6%) and lowest ash (29.9%), and the mixture of vits-treated group had the highest fat content (13.4%) at the end of the storage period. pH in the control and vit- C treated groups was lower than the other two treatments (p>0.05). In conclusion, using of vitamins E and C as well as refrigerator storage are suggested for qualitative preservation of T. suecica algal paste.

The effect of glucose and corn starch at two levels of 15% and 30% for each source on growth performance and carcass composition of juvenile Siberian sturgeon (Acipenser baerii) was assessed. Two weeks after acclimatization to rearing conditions and basal diet, 120 juveniles (25.64±2.80g) were randomly distributed into 12 fiberglass tanks (10 fish per tank, one fish per 35 liter) and fed for a period of 8 weeks with the designated diets in three replicates. The final weight and to tallength, percentage of body weight increase, specific growth rate, mean daily growth, protein efficiency ratio, condition factor, and FCR in fish fed 15% corn starch showed better performance than other treatments (p>0.05). A significant difference in HSI was seen between fish fed 30% corn starch with fish fed 15%glucose (p<0.05). No significant difference was recorded in survival rate among tretments (p>0.05). The highest content of carcass protein was seen in 15% corn starch that was significantly different from 15% and 30% glucose treatments (p<0.05). Fish fed15% glucose had significantly higher content of carcass total carbohydrate than 15%and 30% corn starch (p<0.05). Based on the results, 15% corn starch can increase growth performance, feed efficiency and improve carcass composition in juvenile Siberian sturgeon.

This study was conducted to evaluate the effects of different levels of prebiotic GroBiotic®-A on some growth, hematological, biochemical and immunity parameters of cultured juvenile beluga (Hous huso). Four groups of beluga sturgeon with mean weight of 40.82±5.8 g were raised for 56 days in fiberglass tanks (20 fish to each tank) and fed with different levels of GroBiotic®-A with concentrations of0, 0.5, 1.0 and 2.0% (three replicates were used for each concentration). At the end of trial, some of the growth parameters were calculated and blood samples collected from 36 fish. Then some hematological, biochemical and immunity parameters indifferent groups were determined and compared with control group. Results showed that significant difference in some growth parameters, neutrophil percentage, haemoglobin (Hb), haematocrit (Hct) value and total protein (TP) in fish fed with2.0% GroBiotic®-A were observed compared with control group (p<0.05), but nosignificant difference were observed in other hematological and biochemical parameters (p>0.05). The results suggest that administration of GroBiotic®-A at the level of 2.0% will be improvement some of the growth and hematological parameters and immune function of juvenile beluga. So, using of this supplement asgrowth promotor and immunostimulants was recommended in farmed beluga.

The present study was conducted to evaluate the efficacy of the pH-shift process in protein recovery from whole and gutted common kilka and characteristics of the produced gel compared with muscle surimi obtained with the conventional method. Although both acidic and alkaline methods reduced total pigment (TP) in isolates obtained from the whole and gutted fish, the alkaline version was more effective and the lowest amount of TP was observed in the isolate from gutted fish using alkaline version. The last sample also contained the lowest amount of TCA soluble peptide which was significantly lower than the others. Also, gel produced from the isolatere covered form gutted kilka with the alkaline version had significantly higher water holding capacity and gel hardness but it was weaker than the sample obtained with conventional method. The results were supported with higher relative amount of actomyosin and actin in the structure of the gels produced from the gutted fishisolate and surimi from fish muscle, as reflected in SDS-PAGE. Nevertheless, thewhiteness of the samples recovered with pH-shift process was quite lower than themuscle surimi which reveals the necessity of more research in this area.

In order to improve the properties of myofibrillar protein-based film from silver carp(Hypophthalmichthys molitrix), nanofibrillated cellulose (NFC) at 3 levels (1, 3 and5%) was used. Optimum treatment was determined by evaluating the mechanical, physical and optical properties as well as scanning electron microscopy analysis (SEM). Cellulose nanoparticles had no effect on tensile strength but reduced theelasticity of film (p≤0.05). Water vapor barrier property (WVP) and other physicalproperties of the films were improved by addition of nanofibrillated cellulose at 1%, but decreased at higher concentrations (p≤0.05). Based on SEM, low concentrations of nanoparticles showed more homogeneous dispersion and films had a smoother and better cross-sectional area compared to the higher levels of nanoparticles. Generally, low levels of nanoparticles could be effective to improve the mechanical and physical properties of myofibrillar protein - nanofibrillated cellulose films.

In this study an agar/gelatin bilayer film was produced from agar and gelatin monolayers using the casting method in two phases. Then, the characteristics of this bilayer film, including water vapor permeability (WVP), water solubility, water absorption, mechanical and optical properties were compared with those of monolayer films. The results showed that WVP of the bilayer film (3.25×10-10 g/msPa) was significantly lower than the agar (3.90 ×10-10 g/msPa), and gelatin (4.32×10-10 g/msPa). Absorption of UV light by bilayer film was significantly higher than the single-layer agar and gelatin films. Although the tensile strengthof the bilayer film (10.8 MPa) was higher than the single-layer gelatin (2.86 MPa), it waslower than the single layer of agar film (30.49 MPa) (P<0.05). In conclusion, some properties of agar and gelatin films can be improved by making bilayers film of both biopolymers.