Evaluation of chemical, microbial and tissue properties of surimi of silver carp

Background and objectives: Hydrolysis protein is obtained by breaking the protein into peptides by enzymatic or chemical reactions. In conditions of freezing, compounds with low molecular weight have fatty oxidation and protein degradation, which is associated with bad odor and taste, and affects the qualitative characteristics of the tissue, so if it can be added by adding hydrolysis protein, surimi result will be better at refrigeration and fresh temperatures. This study aimed to investigate the effect of hydrolysis shrimp on chemical, microbial and tissue changes of surimi silver carp (Hypophthalmichthys molitrix).
Materials and methods: Silver carp was converted to bone-free meat by a bone-like machine with a diameter of 2 mm. The non-bulging meat was then washed three times with cold water. The volume of water consumed was 4 times the weight of the meat at each time (ratio 4: 1). In the third step, 0.2% sodium chloride was added. In the final dewatering stage, after pressing the meat on the hand of the fish, a heavy weighing pad was placed on the meat grinder for 10 to 15 minutes to completely remove the water. To prepare hydrolysis shrimp, 250 grams of honeydew taken from Hanijan, peeled and boiled, were hydrolyzed by the alkaline enzyme. Hydrolyzed shrimp was added to surimi at 0.5, 1 and 2% control levels. To carry out this research, for 15 days, refrigerated temperature was measured by measuring microbial load (TVC), biochemical parameters, and texture and color measurements.
Results: The results showed that the hydrolysis protein had inhibitory effects on microbial growth, and in none days, the amount of microbial load did not exceed the permitted limit (107 Log cfu / g) and the microbial load on day zero compared with day 15, in Treatments were significantly increased, but this increase was lower in hydrolyzed protein treatments, especially at 2% level compared to lower levels and control. pH increasing trend during all treatments. Frequency of free fatty acids (FFA) showed a significant difference between different treatments (P <0.05). The highest value of this parameter was observed with respect to day zero to day 15 and in control treatment (4.25 ± 0.03%). In all treatments, peroxide levels did not exceed the permitted level (20-10 mg / kg). In control treatments, and 0.5% of volatile fatty acids increased from (0.4 ± 0.004) to (4.25 ± 0.03%) at the end of the period, while in other treatments this increase was slower. The lowest TBA was measured in 2% treatment. The highest value of this parameter was measured from day zero to day 15 and in control treatment (4.44 ± 0.54 mg malondialdehyde in kilograms). The amount of volatile nitrogen (TVN) showed a significant difference between treatments (P <0.05). The lowest value of this parameter was zero in day 0 and the highest value of this parameter was significant with respect to day zero, to day 15 and control (63.85 ± 1.5 mg/ 100 g sample). Protein hydrolysis also affected surimi's tissue properties. In the results of the color analysis, the brightness parameters (L) and redness (b) decreased and the jaundice parameter (a) increased.
Conclusion: Based on the results, 2% treatment of hydrolysis shrimp could retain surimi's silver carp for up to 12 days.