effect of pickle salting on the quality of silver carp during storage in refrigerator

introduction: fish salting is a traditional method of processing in most countries including iran. there are different methods of salting which can be used for producing different salted products. there is variation in the amount of salt used in the salting process depending on the context of use.salting was done simultaneously with salt penetration into the muscles of fish and water dripping out of the fish tissue, which lead to prevention and/or reduction of microbial and enzyme activity. wet salting using pickel method is one of the methods of salting in which the dry salt is used to remain together with the water dripped out of the muscle in the vessel during salting. this method results in better preservation of fish against the biological spoilage, better taste and suitable distribution of salt in the texture. the importance of this method compared with other methods of salting is its ability in protecting the texture of fish against oxidation because of high rate of salt penetration. using different salting methods affect weight change of fish. that is, the salted fish produced using wet salting method is heavier than the fish salted through dry method. fish breeding especially that of silver carp is one of the important activities of aquaculture in our country. this is because of high rate of silver carp production and provision of a product with a better taste to markets. to assess the effectiveness of wet salting during refrigerated storage (4˚ c), in this study physicochemical, microbiological and sensory evaluation of salted silver carp would be employed. materials and methods: the fresh silver carps with weight of 0.5 kg were purchased from market (bandar torkman, north iran) and transported in isothermal iceboxes to the fish control quality laboratory at ashoradeh island in 2012. the fishes were cleaned and salted with 10 and 20% concentrations and then stored in refrigerator (+4°c). chemical parameters (humidity, protein, salt, pv and tba), ph, microbial parameters (tvc, ptc, and halophile) and sensory analysis were measured at 0, 3, 6, 9 and 12 days. the experiments were performed in three replicates. results & discussion: the present study showed that by increasing the salt concentration from 10 to 20 % at 4 ° c the salt amount of salted fish muscle changed from 10.70 to 13.60 after 12 days of refrigerated storage. this suggests that an increase in salt concentration result in higher salt absorption. the difference between the results of two treatments in different times were statistically significant (p <0.05). a significant (p <0.05) reduction of moisture was observed with the increase of salt concentration during refrigerated storage. with increasing salt concentration from 10 to 20% the fish muscle losses more water and the level of moisture full down. the ph and protein of salted fish decreased during refrigerated storage. peroxide values increased significantly in all treatments during refrigerated storage. however, this increased is higher in 20% and exceeds the acceptable level after 12 days of refrigerated storage. in this research thiobarbituric acid value increased during refrigerated storage. but the tba was lower than the acceptable level in all treatments during refrigerated storage.tvc increased significantly (p <0.05) in amount during refrigerated storage of two treatments. the change in 10% recorded a higher rate than that of 20%. the concentration of salt in heavy salting in comparison to light salting delayed bacteria growth. thus increasing salt concentration decreases the bacteria growth. in this research the amount of ptc decreased significantly (p <0.05) in two treatments during refrigerated storage. the halophile level increased due to an increase in absorption of salt in the fish suggesting that higher level of salt absorption affected positively the growth rate of halophile. the texture and taste of salted fish decrease with the increase of salt concentration. thus 10% salt concentration produces a better texture and taste than those produced in 20% during refrigerated storage. the reduction of salt concentration from 20 to 10% caused the bad odor in the fish. the best smell was observed in high salt concentration and low time of storage. the color quality of fish changed during salting and refrigerated storage, so that the salted fish with 10% had a better result using sensory analysis. conclusion: the results of physicochemical parameters showed that the amount of salt, pv and tba increased whereas humidity, protein and ph decreased during refrigerated storage. the tvc and halophile of salted fish increased and ptc decreased during refrigerated storage. the taste, texture and color of salted fish treated with 10% salt concentration and the odor resulted from 20% salt concentration were evaluated appropriate by the related assessors. the results of sensory evaluation and physicochemical parameters of salted fish indicated that the treatment of 10 % was better than the treatment of 20 % in this research. regarding the importance of salt in food products and the effects it has on human health help conclude that wet salting with 10% concentration should be recommended for silver carp during refrigerated storage (4˚ c).