نشریه علوم و فنون شیلات
سال چهارم شماره 3 (پیاپی 12، پاییز 1394)

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 adsorption capacity, protein solubility, emulsifying capacity, emulsion stability, gel forming ability, and thiobarbituric acid. Increase in ice-storage duration increased the density and thiobarbituric acid of surimi powder(p

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 (p0.05). Primalac significantly decreased the cholesterol levels (p0.05). 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 minced meat, both unwashed mince and surimi were put in zip-lock bags and stored at -18°C for a period of 3 months. No significant changes (p>0.05) in protein and total fat in both treatments were observed during different periods of storage. Peroxide value (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 surimi treatment 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 surimi after three months of storage. In conclusion, surimi from common carp could preserve 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 upward trend 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 Alcalase treatment. However, there existed no significant difference between the two treatments.

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 (4°C) 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 was1.38􀀀109 cells/ml and the production
yield was about 1.7 gr/l. The cell viability in vitE-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 total length, 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 (p0.05). The highest content of carcass protein was seen in 15% corn starch that was significantly different from 15% and 30% glucose treatments (p

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 of 0, 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 in different 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 with 2.0% GroBiotic®-A were observed compared with control group (p0.05). 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 as growth 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 isolate recovered 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 fish isolate and surimi from fish muscle, as reflected in SDS-PAGE. Nevertheless, the whiteness of the samples recovered with pH-shift process was quite lower than the muscle 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 and 5%) 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 the elasticity of film (p≤0.05). Water vapor barrier property (WVP) and other physical properties 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 strength of the bilayer film (10.8 MPa) was higher than the single-layer gelatin (2.86 MPa), it was lower than the single layer of agar film (30.49 MPa) (P