Chemical changes and shelf-life of conventional surimi and proteins recovered using pH change method from common carp (Cyprinus carpio) muscle during 5 months storage at -18ºC

Chemical changes and shelf-life of common carp (Cyprinus carpio) surimi prepared by conventional washing method and solubilization by acid and alkali processes were investigated during 5 months of storage at -18 °C. Results showed that surimi produced with acid and alkaline solubilization is significantly higher yield than the conventional surimi. Protein solubilization by using acid and alkaline process was high compared with conventional method during storage in freezer except in the first month. Gel electrophoresis patterns showed a significant difference in hydrolyzing of myosin and actin proteins that was observed with increasing storage time. Surimi samples prepared by conventional method indicated more hydrolization, especially in the light chain of myosin during frozen storage. Evaluating the color characteristics (L*, a*, b*) of surimi samples showed that protein produced by using of pH 11 has the highest lightness after conventional surimi. Also, more whiteness in surimi prepared by conventional method was due to effective removal of myoglobin during washing. At zero month, total fat in the surimi samples prepared with acid and alkaline process was low than the surimi samples prepared by conventional method that it can intent to shelf-life increase and health of the product during storage

The shelf-life of conventional surimi and recovery of functional proteins from silver carp (Hypophthalmichthys molitrix) muscle by an acid or alkaline solubilization process during frozen storage

The shelf-life of conventional surimi and isolated proteins that modified by acidic pH (2.5) and by using alkali pH (11) from silver carp (Hypophthalmichthys molitrix) was studied during months of storage at -18±2 °C. For conventional surimi, three washing steps were used. In the third stage of washing, 0.2% NaCl was used to withdraw more water. The result showed that isolated protein by alkaline pH has a higher efficiency. In the obtained result of percent yield and the recovery of protein product, isolated proteins showed higher values than conventional surimi. Isolated protein by using acid-aided processes had lower lightness and whiteness score, compared with alkaline-aided process and surimi prepared by a conventional washing method during frozen storage. The concentration of myosin heavy chain and actin were varied with solubilizing pH. Also, the lowest downfall of protein and the best surimi quality were found in produced samples with alkaline-acid aided process

Effects of Daphnia magna and Artemia nauplii on growth performance in Persian sturgeon Acipenser persicus larvae

This study was carried out in a completely randomized design 3×3×4 factorial arrangement in three periods of rearing in spring 1997. Density of 300 larvae was assigned for each oval tank with 0.1m2 surface area, 30cm deep, a volume of 20lit and 0.25 lit/min of water flow per minute at Shahid Rajaie fish breeding and culture center in Sari, north of Iran. The fries were divided into three groups according to their feeding regimes and fed with each of Artemia or D. magna separately, and mixture of the two (50% Artemia+50% Daphnia) in ratioes of 80, 100 and 120% of their body weights in the first period and 30,50,70% of their body weights in the second and third period of rearing. Each period lasted 72 hours. The result indicated, significant differences (p<0.005) between food organisms, body weight gain and Food conservation Ratio (FCR) in the first and third period of rearing. The highest body weight gain was found in 120% food ratio in the first period. The best survival rate achieved with fries feeding at 70% body weight of Artemia nauplii and mixed food in the second period of rearing. The highest growth rate, survival rate and the best FCR obtained when Artemia fed as live food to fries. There were no significant differences between Artemia and mixed food in this study. It seems that mixed food (50% Artemia +50% Daphnia) given at 70% of larval body weight results in a better performance

Chemical and microbiological changes of salted Caspian kutum (Rutilus frisii kutum) roe

Salted kutum roe was prepared by soaking in brine to a traditional procedure. Proximate composition (moisture, protein, lipid, pH, ash and salt content), total volatile basic nitrogen (TVB-N), fatty acid profiles and microbiological characteristics of raw and salted roe of Caspian white fish (Rutilus frisii kutum) were determined. The results indicated that protein and moisture contents were significantly higher in raw roe compared to salted one (28.81 and 61.07% to 23.99 and 51.57%, respectively). Significant differences in ash and salt contents were obtained among different treatments. TVB-N in all samples was less than 25mg/100g. The gas chromatography (GC) analysis showed that the major saturated fatty, monounsaturated fatty acids and poly unsaturated fatty acids were 16:0, 18:1n-9, and 22:6n-3, respectively. Aerobic plate count (APC) and Total Coliform Count (TC) in all samples were significantly higher (p<0.05) in raw roe (5.33 logCFU/g and 210 MPN/g) compared to salted roe (1.23 log CFU/g and 1.2 MPN/g). None of the samples contained Escherichia coli, Salmonella, Clostridium perfringens or yeast

Study of genetic structure of Rutilus frisii kutum in Golestan province coastal waters using microsatellite markers

To determine the genetic diversity of Rutilus frisii kutum, 25 samples were collected from Gharesou and Gorgan-rud rivers in April 2008. The genomic DNA was extracted from the caudal fin using phenol- chloroform method and investigated with 10 microsatellite loci. All the 10 investigated loci were polymorphic and showed variability in the two populations of the rivers. The mean number of allele per locus at population level and the observed heterozygosity ranged from 4 to 13 and 0.22 to 1.00, respectively. The FST value between populations was 0.014 (P<0.05), and the analysis of genetic variation distribution indicated a very high within population variation (99%) while among population variation is low (1%). Highly significant deviation from hardy-Weinberg equilibrium was observed in both populations which can be attributed either to the presence of null alleles or to the genetic bottleneck. The results indicated a high level of genetic variation in this species and we concluded that there is more than one population of Rutilus frisii kutum in Golestan coastal waters

Antioxidant properties of sodium acetate, sodium citrate and sodium lactate on lipid oxidation in rainbow trout (Onchorhynchus mykiss) sticks during refrigerated storage (4˚C)

This study was carried out to investigate the rate of lipid oxidation in fresh rainbow trout (Onchorhynchus mykiss) and in the sticks treated by (2.5% w/v) sodium acetate (NaA), sodium citrate (NaC) and sodium lactate (NaL). The pH value, free fatty acid (FFA), thiobarbituric acid (TBA) and sensory evaluation (odor, flavor and color) were determined on 0, 3, 6, 9 and 12 days of storage. The results showed that TBA and FFA in control were significantly higher than those in the other groups (P<0.05). Sticks immersed in NaA indicated a significant difference in formation of free fatty acids in comparison with other sodium salt-treated samples on 9 and 12 days after storage. Sticks dipped in NaL had a maximum level of pH at the end of the storage, whereas samples treated by NaA achieved significantly the lowest value of pH, 9 days after storage. Organoleptic assessments of the samples expressed more acceptability of sticks immersed in sodium salt solutions than the control after 3 days of storage. These indicated that sodium salts, particularly sodium acetate, have antioxidant properties

Fillet quality grading of common carp (Cyprinus carpio) by fish size using mathematical equations

Quality grading and nutrition value determination of fish are nowadays necessary for aquatic processing. The present study was conducted to investigate a new, applied and cheap method of fillet quality grading for common carp (Cyprinus carpio) using fish size, based on mathematical equations. For this reason, 61 specimens of cultured market size carp were used and after filleting, their moisture, lipid, protein, energy and ash content were measured. Then, the relationships between proximate composition components of fillet and fillet length were studied. Results showed that there is an inverse linear regression relationship between logarithm of moisture content and logarithm of fish length (P0.05). Regarding the relationship between proximate composition of cultured carp fillets and fillet length machine fish sorting based on fish length and grading of moisture, lipid and energy content is feasible. We also found it feasible to determine type of processing and proximate composition of the prepared common carp

Inhibitory impacts of natural antioxidants (ascorbic and citric acid) and vacuum packaging on lipid oxidation in frozen Persian sturgeon fillets

This study was aimed to investigate effects of aqueous citric acid (CA) and ascorbic acid (AA) on lipid oxidation in comparison with effect of vacuum packaging in order to find better treatment to delay improper changes in the Persian sturgeon (Acipenser persicus) fillets during frozen storage due to lipid oxidation. In this study traditional packaging, vacuum packaging, ascorbic acid solution (0.5 %) and citric acid solution (0.5 %) were considered as treatments. Rancidity development was measured by several biochemical indicators including Free Fatty Acids, Peroxide values and Thiobarbituric acid. Also pH, expressible moisture and sensory properties were measured during 6 months storage. Results showed that free fatty acid (FFA), primary and secondary oxidation products of control samples were significantly higher than those in other treatments (p<0.05). Also, expressible moisture and pH value of treated samples were significantly lower than those in control (p<0.05). However both antioxidants (AA and CA) extended shelf life of frozen fillets but rancidity development in CA treated samples was higher than other samples during storage. Results showed that all three treatments had significant effect on delaying lipid oxidation (p<0.05) but usage of AA and vacuum packaging had the best effect on delaying lipid oxidation and increasing shelf-life of fillets (p<0.05) . Thus the employment of AA and vacuum packaging alone or in combination with other protective strategies is recommended

Effects of washing bouts and times on surimi quality prepared from common carp (Cyprinus carpio)

To prepare common carp surimi, washing was done in different steps (1, 2 and 3 steps) and times (5, 10 and 15 minutes) and the treatments were tested statistically. The results showed that the 10 minutes washing for 3 times produced surimi that was superior to minced meat in color desirability (1 for surimi versus 7 for minced meat), odor desirability (2 versus 7), flavor desirability (0 versus 5.5) and on the general properties. The process of surimi production also increased water binding capacity from 0.14 to 0.64, pH from 6.21 to 7.34 and gel forming ability from A score to AA score. Tests of moisture content, protein, fat, ash, and total volatile nitrogenous bases (TVB-N) were performed on the samples of the minced meat and the selected treatment of the produced surimi. The extent of changes of these parameters were calculated and compared with available standards. We found that the common carp surimi lacks undesirable flavor and smell of fish and has suitable rheological properties for preparation of different kinds of fish paste products

Inhibitory effect of citric acid on rancidity of frozen catfish (Silurus glanis)fillets

The effect of aqueous solution of citric acid (CA) on the lipid stability of the European catfish (Silurus glanis) fillets during frozen storage (up to 6 months) was investigated. Rancidity development was measured by several biochemical indices (free fatty acids, peroxides and TBA) and complemented by the measurement of expressible moisture and sensory evaluation (flesh odor, consistency and flesh appearance). The CA treatment led to some lower free fatty acids (6.43% oleic acid in total lipid at month 6), peroxides (7.98meq oxygen/kg lipids, at month 6) and secondary compounds formation (2.16mg malondialdehyde/kg fish sample). Lower peroxide, thiobarbituric acid-reactive substance (TBA), free fatty acids (during 0,3 and 6 months frozen storage), and expressible moisture (month 6) values were obtained from CA-treated fish fillets than the untreated (blank control) ones (P<0.05)