Ultra High Pressure Homogeneous-Phospholipid Modified Soy Protein Isolate And Its Application In Ice Cream

Soy protein has been widely used in the food field because of its high nutritional value,low cost and excellent functional properties.In order to better use it,people use various methods to modify the soy protein and further enhance the functional properties of the soy protein.In this experiment,the soy protein isolate?SPI?was modified with an ultra-high pressure homogenous-phospholipid complex method,and then the structural and functinal properties of the mixed system were studied,and the protein was frozen at a low temperature and frozen for frozen foods such as ice cream.The requirement of liquid stability,a preliminary study of the low-temperature storage and the stability of frozen emulsions of various modified protein products,in order to obtain a soy protein isolate suitable for frozen foods such as ice cream,and to add the modified protein to ice cream to explore Its impact on the quality of ice cream.The results are as follows:?1?Under the optimized optimized conditions of ultra-high pressure,SPI emulsification increased from 49.659 m2/g to 65.454 m2/g,and the emulsification stability was 36.636 min.Through the combination with phospholipids,the emulsifying and emulsifying stability of SPI-PLW was higher than that of SPI,the emulsification increased from 65.454 m2/g to 87.170m2/g,and the emulsion stability From 36.636 min to 43.52 min.?2?Ultrahigh pressure homogenous-phospholipid complex modification can improve the structural properties of soy protein isolates:after exposure to ultra-high pressure homogeneous,the amount of exposed thiol groups and total sulfhydryl groups contained in SPI is significantly reduced?p<0.05?.After the introduction of phospholipids,thiols can be reduced.Oxidation increased the sulfhydryl content.SPI undergoes high-pressure homogeneous,resulting in the exposure of its hydrophobic groups,which increases its hydrophobicity.By studying the circular dichroism spectrum,it can be concluded that the SPI undergoes a certain change through the ultra-high pressure homogeneous treatment,its secondary structure changes,the total amount of?-helix contained increases,and the total amount of?-sheets contained decreases,including irregular curling.The total amount of structure increases,and its spatial stability decreases,and after the addition of phospholipids,the structure of the globulin is stabilized.It can be seen from the SDS-PAGE pattern that high-pressure homogenization dissociates the SPI and a new subunit structure appears,making the SDS-PAGE pattern bands darker,and the addition of phospholipid subunits also changes.By scanning electron microscopy,the SPI of high pressure homogeneous changed from a globular structure to a platelet,and the GSPI-PLW sheet structure obtained by combining with phospholipid became small,thin,smooth and uniform.?3?Ultrahigh pressure homogenous-phospholipid complex modification can also improve the functional properties of soy protein isolates:Ultra-high pressure homogeneous can greatly increase the solubility,emulsification and foaming properties of SPI?P<0.05?,while also making foam stability and Centrifugal precipitation rate weakened.After the ultrahigh pressure homogeneous SPI and phospholipid were compounded,their functionality was further improved.The emulsification activity of GSPI-PLW increased by 32.72%,the emulsion stability reached 43.52min,and the bubble stability was increased by 118.63%compared with unmodified SPI.Increased122.22%.?4?The stability of SPI,GSPI,SPI-PLW,and GSPI-PLW emulsions after refrigerated and frozen storage was investigated using the D_3,2,aggregation degree,degree of coalescence,centrifugal sedimentation rate,and oil yield index of various sample emulsions.The stability of the SPI emulsion under refrigeration is less than that at room temperature.Under refrigeration conditions,the stability of the SPI emulsion has been affected more,and all types of emulsions have started more or less.Gather and coalesce.The results of the study showed that the stability of the emulsion after chilled and frozen storage of the compound phospholipids was improved,and the degree of coalescence of 77.45%of the SPI frozen emulsion was reduced.?5?When the SPI portion is used to replace the milk powder in the ice cream,the ice cream has problems such as low expansion rate,easy melting,rough mouthfeel,and so on.A variety of modified soybean protein was added to the ice cream instead of the milk powder.The control experiment showed that the standards for the ice cream made from the ultra-high pressure homogenized-phospholipid complex modified soybean protein isolate?GSPI-PLW?were all strong.For other types of soy protein ice cream.Compared with ordinary low-fat ice cream paste,after adding GSPI-PLW,its viscosity is greater,more stable when aging,and can make the fat ball more thoroughly dispersed;so that ice cream expansion rate,easier to preserve,softer mouthfeel and so on.GSPI-PLW ice creams have an expansion rate of up to 72.30%and a melting rate of 33.17%,which is better than traditional low-fat ice cream.