Document Type : Research Article
Authors
Caspian Sea Ecology Research center
Abstract
Introduction: Evaluation of fish and seafood markets in Iran show that people have little interest to consume fish, despite the fact that fish consumption in developed countries is the rapid growth. However, despite the significant sources of demand for fish consumption of fish is generally seasonal. One of the problems consumers clean and ready to cook the fish, which need to experience and time, although it is common for all the fish, but the warm water cultured fish is more important, therefore, must be programmed in such a way that the fish are supplied all year. The fish processing provides the possibility that fish that are produced in a limited time and gradually throughout the year are marketed. Due to high production of warm water fish and using of small-scale and traditional methods for processing of fish such as salting and smoking, is necessary to use from modern processing methods for production of high quality of fishery products from fish particularly warm water fish such carp, silver carp, grass carp and big head.
In 2004, a joint project with title "improvement of silver carp processing and production of different products from fish" was signed between Iranian Fisheries Science Research Institute and Rivo Institute and Wageningen university of Netherlands. According to the project 7 sub projects were defined that including: quality of fish sausage, fish cheese, fish snake, fish ball, fish ice cream, trimming machines for production of fish fillet and pin bone machines for production of deboned fillet. Two main objectives of the project were production of high quality of fish fillet with low fat and bone and development of various products from silver carp for introduce to market. Fish Cheese is produced from coagulation of soluble proteins (sarcoplasmic proteins) of fish. The aim of this study was to extraction and precipitatation of sarcoplasmic proteins of silver carp (Hypophthalmichthys molitrix) and its use in fish cheese formulations.
Materials and methods: After washing, the fish was beheaded, gutted, and again washed and bones were manually separated. Fish fillets were grained and prepared for surimi production. Minced fish were washed three times in 10 ° C water ( 1 to 4 w/v) for 15 minutes, and the third stage was rinsed in the brine (0.3%). For coagulation and concentration of sarcoplasmic proteins were used from acetic acid (5%) and centrifuge in 5000 rpm for 15 minutes respectively. At the end of the process the sugar and sorbitol, (each in the amount of 4%) and tri sodium polyphosphate was used in the amount of 0.3%. Proximate composition (total protein, total fat, moisture and ash) and chemical parameters (peroxide value (PV) and total volatile base nitrogenTVB-N) and microbial analysis (total viable counts) were examined for three forms of fish (minced fillets, concentrated protein and fish cheese). All examinations were done as standard methods for food analysis.
Results & Discussion : The results showed that the mean of fat, moisture, ash and protein in silver carp minced was 2.71%, 79.44%, 0.91%, 16.90%, in the concentrated sarcoplasmic protein 1.16%, 81.97%, 0.42% 16.41% and in fish cheese 2.30%, 48.41%, 3.46% and 17.50% respectively. The optimized formula of fish cheese was obtained with 22.26% of protein. The mean of TVB-N and PV in minced fillets were 11.32 mg/100 and 1.51 meqo/kg, in the concentrated sarcoplasmic were 13.63 mg/100 and 3.65 meqo/kg and fish cheese 15.03 mg/100 and 5.38 meqo/kg respectively. The mean total count of bacteria in minced silver carp was 2.7 × 104 cfu/g. The most and least of TVC were 4.5 × 104 and 1.1× 103 cfu/g respectively. Mean of molds and yeasts in minced fish was 3.5 × 103 cfu/g. Highest and lowest of mold and yeast were 7.2× 103 and 1.2× 103 cfu/g respectively. The mean total count of bacteria in concentrated sarcoplasmic protein of silver carp was 1.3 × 104 cfu/g. The most and least of TVC were 2.5 × 104 and 8.1× 103 cfu/g respectively. Mean of molds and yeasts in concentrated sarcoplasmic protein were 3.1 × 103 cfu/g. Highest and lowest of mold and yeast were 5× 103 and 1.5× 103 cfu/g respectively. The mean total count of bacteria in silver carp cheese was 1.8 × 103 cfu/g. The most and least of TVC were 4 × 104 and 8.5× 103 cfu/g respectively. Mean of molds and yeasts in fish cheese was 3.2 × 103 cfu/g. Highest and lowest of mold and yeast were 7.2× 103 and 1.2× 103 cfu/g respectively. Total count of bacteria in different forms of silver carp showed that the number of bacteria in the range of log 4 and the final product was a slight decrease (in some treatments). Changes in the number of bacteria in the processing time depend on two factors, time and temperature. Processing in low temperature and little time are caused that the count of bacteria will be at the standard level. For introduce the new product to market is needed to additional examination such as sensory and organoleptic evaluation.
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