| In recent years,surimi and surimi products have become more and more popular for consumers because of their delicious taste,rich nutrition and low prices.The characteristics of surimi gel is one of the most important properties of fish meat and surimi.However,due to its poor gel strength,freshwater fish brings consumers a bad eating experience and also limits its application in high-end surimi products.Studies on the use of starch,protein and other exogenous additives to improve surimi gel are often reported.Although these substances have improved the gel properties of surimi products to a certain extent,they also caused a series of shortcomings,such as single product,reduced nutrition and increasement of by-products.In addition,the carp tissues are prone to mechanical damage and microbial contamination during the processing of silver carp,which leads to a very low quality and economic value during this process.The polyphenols and polysaccharides in the mallotus obongifolius extract can not only promote the cross-linking of fish protein and enhance the gel properties of surimi and its products,but also can be used as a biological preservative to inhibit lipid oxidation and microbial reproduction to extend the shelf life of minced meat products,it is a safe,environmentally friendly and effective external additive,which has good development potential in the food industry.By preliminary exploring the effect of different mass fractions of mallotus obongifolius extract on the characteristics of surimi gel and the preservation of surimi products,it provides experimental basis and data reference for its development and application in food.The main research results of this experiment are summarized as follows:(1)The polyphenol content of the mallotus obongifolius leaves at 70?,30 min,1:30 is 9.43%,and the total phenol concentration of the mallotus obongifolius water extraction is 9.43 mg / m L,the purity is 57.69%,the content of soluble polysaccharide is 3.93%,the concentration is 3.93 mg / m L,and the purity is 30.01%.Therefore,the main substance in the mallotus obongifolius extract is a polyphenol compound.Mallotus obongifolius extract has the same DPPH free radical scavenging rate and reducing ability as Vc,which has good antioxidant effect.In addition,tea polyphenols have high stability in ethanol,acidic conditions,and sugar-containing solutions,and are not suitable for storage in high temperatures and redox agents.(2)The effects of adding mallotus obongifolius extracts with different mass fractions on the characteristics of surimi gel are obviously different.With the increase in the mass fraction of mallotus obongifolius extract,the whiteness of surimi gel decreased significantly,water holding capacity,gel strength,hardness,cohesion and chewness all increased first and then decreased,but the springiness did not change significantly.When the added amount of mallotus obongifolius extract was 0.375%,the above indicators reached the maximum.In the rheological properties,0.375% of mallotus obongifolius extract can reduce the G 'value and G "value of surimi gel in the early stage of heating,and increase the G' value and G" value of the surimi gel in the late stage of heating.The tan? value of surimi gel was reduced during heating,and the results showed that adding mallotus obongifolius extract can improve the viscoelastic properties of surimi and has good rheological properties.In addition,in terms of the mechanism of improving the properties of surimi gel,the chemical force shows that the mallotus obongifolius extract has no significant effect on ionic bonds,hydrogen bonds,and hydrophobic interactions,while the disulfide bond reaches the maximum at 0.375%.SDS-PAGE showed that the MHC band degraded and moved up,but no obvious change in the AC band.At the same time,there was aggregation of polymer protein on the upper end of the concentrated gel.Fourier infrared spectroscopy has no significant effect on the protein molecular structure of surimi gel.Therefore,mallotus obongifolius extract mainly promotes the covalent crosslinking of proteins by promoting the formation of disulfide bonds and non-disulfide covalent bonds ?-(?-Glu)-Lys,forming protein coagulation with a small pore size and a dense structure Glue.(3)During the storage of silver carp surimi products at 4 ?,The preservation effect of mallotus oblongifolius extract on carp surmise products was studied using sensory quality,water holding capacity,total bacterial count,p H,TBA and TVB-N value.Regular sampling and analysis of Control and treated samples to understand the microbiological and chemical properties of the senses.The results showed that the mallotus oblongifolius extract has a good antibacterial effect,it can inhibit the growth delay,microbial oxidation of fat,reducing the TBA and TVB-N value,extend the shelf life of surimi products.The effects of adding 0.375% extract of mallotus oblongifolius was the best. |
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