Application Of Extruded Soybean 7S Protein In Juvenile Carp Feed

Soybean protein is a high quality protein source,but it often produces allergic reaction to aquatic animals in feed application.In order to find a more effective way to reduce the allergen of soybean antigen protein improve the utilization rate of soybean protein.Based on the antigenicity of soybean 7S protein,the extrusion process was optimized,and the secondary structure was analyzed by Fourier transform infrared spectroscopy to analyze the relationship between structure and antigenicity.Finally,the effect of 7S protein gradient(0%,2%,4%,6%,8%,10%)on carp was replaced by the optimal process.Including effects on growth performance and histology of intestine,spleen,liver and pancreas;effects on serum antioxidants;effects on specific immunoglobulins;effects on allergic-related proinflammatory cytokines.The experiment is as follows.(1)To explore the effect of extrusion on the secondary structure and antigenicity of soybean 7S protein.The soybean 7S protein separated and extracted by alkali solution and acid precipitation was extruded.The antigenicity of soybean 7S protein was detected by ic-ELISA under different extrusion conditions.The FTIR spectra of soybean 7S proteins before and after the best extrusion conditions were analyzed.The results showed that the antigenicity of soybean 7S protein decreased with the increase of extrusion temperature and screw speed,as well as feeding speed.The effect of water content on antigenicity is low.The best extrusion puffing temperature is 130 ?,the feeding speed is 35 g/min,the screw speed is140 r/min,and the water content is 12%.Under this condition,the antigenicity of soybean 7S protein was the lowest at 20.06%,which was lower than 20.89% in orthogonal test.The secondary structure was analyzed by FTIR spectroscopy,and the contents of ?-helix,?-sheet,and ?-turn of soybean 7S protein were significantly reduced,and the content of random curl was significantly increased(P < 0.05).The extrusion puffing process can reduce the antigenicity of soybean 7S protein to a certain extent,and it helps to improve the effective utilization of soybean protein.The relationship between the antigenicity of soybean 7S protein and its structure needs further investigation.(2)In order to investigate the effects of soybean 7S protein on growth performance,intestinal,spleen and hepatopancreas histology,serum immunity and anti-oxidation of youngcarp,the feed test was carried out by adding 7S protein of soybean after optimal extrusion process to the feed of juvenile carp.The results showed that the final mass and WGR?PER of young carp decreased significantly(P < 0.05)soybean 7S protein,FCR increased without significant change(P < 0.05).The stimulation and stimulation and injury on intestinal,spleen and hepatopancreas organs were increased.Serum antioxidant ROS?serum antibody IgG?IgM?IgE increased significantly with the addition of soy 7S protein(P < 0.05).Combined with all the influencing factors,the optimum amount of soybean 7S protein after optimal process treatment was 4%,within a certain acceptable range,or even 6%.(3)With the increase of soybean 7S protein extruded,IL-1?,IL-2,TNF-?,NO serum proinflammatory cytokine levels increased significantly(P < 0.05).The sensitivity of four proinflammatory cytokines to antigenic proteins was significantly different.The highest increase in secretion levels due to soy protein 7S IL-1?,followed by differences in sensitivity may be a new breakthrough in reducing or eliminating antigen responses.