Studies On Properties Of 7S And 11S Modified By Enzyme And Application In Pork Sausage

One of the limitations in the usage of soybean proteins is the lack of desired functional attributes to be incorporated into various food formulations.Some functional properties of soybean proteins should be enhanced or improved.The problem solved immediately is to investigate the special protein for different food by enhancing or improving the properties of soybean proteins.Soybean proteins consist of two major components,7S and 11S globulins,which play an important role in all phisico-chemical properties of the soybean proteins.At the present,there are not many researches on the technology of respectively modifying 7S and 11S globulins at the molecule structure.Consequently,it is important to find a special soy protein by the use of 7S and 11S globulin of the physico-chemical properties,which can enhance the competitiveness of enterprises.In this paper the most suitable one was determined from six varieties and the correlation between subunits composition and ratio of 7S to 11S on the quality of pork sausage was formed.The functional and structural properties of SPI,7S and 11S were analyzed.The effect on the quality of pork sausage was compared by adding the hydrolysates of differents DH values of 7S and 11S by the hydrolysis of Bromelain, Tryptic,Netrease,Protamex,Alaclase.The proper hydrolysates were determined for pork sausage and technical parameters were optimized.In additon,the functional and structural properties were evaluated of 7S and 11S by hydrolysis of Alaclase and the correlation beween the functional properties and the quality of pork sausage was found.At last,the effect on the pork gels adding different hydrolysates of 7S and 11S were compared and the relationship of chemical interation and the quality of pork sausage was set up.The main research results are listed as follows:1,The correlation between subunits composition and ratio of 7S to 11S on the quality of pork sausageThe results showed that zhong 36 SPI improved TPA,GS and yield of the pork sausage significantly in comparison with adding other varieties of SPI.After a statistical correlation analysis between the component of protein subunits and the indexes of pork sausage,it was found that the significant degree was varied with different subunits.Subunitβand the content of 7S and 7S/11S had a significant positive correlation with springiness,chewiness,yield and GS.The content of 11S had a great significant negative correlation with them.2,The effect on the quality of pork sausage adding 7S and 11S hydrolysates by different proteases The result showed that the hydrolysates of 7S and 11S by the hydrolysis of Bromelain and Alclase could improve the quality of pork sausage,which was better than that of SPI in the market by copmaring the quality of pork sausages adding 7S and 11S by the hydrolysis of five proteases.The optimum quality of pork sausage adding 7S and 11S hydrolysate were investigated.When adding 7S and 11S hydrolysate by Bromelain,the optimum parameters were DH 7%,addition 1.5%and DH 5%,addition 1.0%respectively. While adding 7S and 11S hydrolysate by Alaclase,the optimum parameters were DH 11%,addition 1.5%and DH 10%,addition 1.5%respectively.By the comparison of pork sausage adding 7S and 11S hydrolysates by Alaclase with different ratio and additions,appropriate parameters for the best were determined: the ratio of 7S to 11S hydrolysate by Alaclase was 3.5∶1,addition of that was 0.5%.3,The study on the change of the functional properties of 7S and 11S by the hydrolysis of AlaclaseThe solubility and EAI of 7S and 11S were evidently improved by the hydrolysis of Alaclase.But WHC of that was decreased and FAC of that was not significantly increased.The correlation between functional properties and quality of pork sausage showed that solubility and EAI had a significant positive with springiness, cohesiveness,resilience and yield,however WHC had a significant negative with them.FAC and ES had no significant correlation with them.4,The study on the change of the structural properties of 7S and 11S by the hydrolysis of AlaclaseThe molecular structure,conformational changes and interactive bonds in 7S and 11S were examined by SDS-PAGE,SEM,FT-IR infrared spectroscopy,Raman spectroscopy,as well as hydrophobicity and sulfhydryl content.The result of SDS-PAGE showed that the subnits of 7S and 11S were decreased in all hydrolyzed protein.Acidic subunits were easlily hydrolyzed than basic subunits of 11S.The results showed that conformational changes were great in all hydrolyzed protein,and the degree of changes was depend on the degree of hydrolysis.The analysis of scanning electron microscopy indicated that the size of granula bacame more bigger with increasing the DH.The result of FT-IR suggested that the content of conformational changed and the secondary structure changed.It may be related to the changes of hydrogen bond.We found that hydrophobicity and sulfhydryl content fast increased in all modified protein,and they were greatly affected by DH value.The phenomena suggested that the protein structure changed. 5,The influence on the mechanism of pork gelWHC and CL of pork sausage adding 7S and 11S hydrolysates were greatly improved.The chemical interactions and protein structures in order to maintain pork surimi protein structure and stability changed during pork gel forming.Static interaction decreased significantly,while hydrogen bonds,disulfide bonds and hydrophobicity increased significantly with surimi gel forming adding 7S and 11S hydrolysates.Static interaction had no significant correlation with the quality of pork sausage.So it was not the main chemical interactions to maintain pork gel network structure.Disulfide bonds and hydrophobicity had a significant positive correlation with the quality of pork sausage,therefore they were the main chemical interactions to maintain pork gel network structure.The contribution of hydrogen bonds maintaining pork gel protein structure was different adding 7S and 11S hydrolysates.Hydrogen bonds had a significant positive correlation with the quality of pork sausage adding 7S hydrolysates.However it had a significant negative correlation with the quality of pork sausage adding 11S hydrolysates.The analysis of SEM indicated that the pork gel network structure adding 7S and 11S was greatly improved,which was compact,relatively uniform,no empty.Based on aboved facts,we can found that there was a significant correlation between subnits of protein and quality of pork gels.Physi-chemical properties,the structure of 7S and 11S hydrolysates and quality of pork gels were closely correlated. So we could select suitable soybean protein in accordance with the requirements of meat products.