Study On Functional Properties Of Mixed Proteins

Food quality, especially the food texture depends on the functional properties(E.g. Solubility, foaming property, emulsification, gel property, and so on) of food protein.In recent years, the modification technology of protein functional properties becoming the hot point in food industry, also some researchers turn to functional properties of mixed protein, but lack of systematic experiments design and analysis method in searching functional properties of mixed protein and their interactions. This paper using SPI(soybean protein isolate)、EAP(egg albumine protein) and WPI(whey protein isolate) as crude material, experimenting the functional properties’ change tend of mixed proteins. Then applied Simplex Lattice method on mixed proteins’ foaming capacity, gel property and build a regression model, analyzed different types of proteins’interactions. This study in the sake of providing thoughts and methods for modifying proteins’ functional properties, meanwhile, lowering the costs and complementing nutrition, so that protein can be more widely used in food industry.The main contents and conclusions are as following:(1) Functional properties of soybean-albumen protein composite blendsIt is found that the compound powders of soybean protein and albumen show Antagonistic effect on foam ability; while that of gel strength, hardness, springiness, gumminess and chewiness are strong synergistic effect; however, no significant effect on solubility. On the other hand, it is show that the network structures of Soybean protein isolate contain abundant of smaller pores and less crosslinking of aggregate; however, the network structures of albumen contain larger pores and dense crosslinking of aggregate. While the network structures of compound protein powder are in between the Soybean protein isolate and albumen.(2) Functional properties of albumen-whey protein composite blendsIt is found that the compound powders of albumen and whey protein isolate show light synergistic effect on foam ability; while that strong synergistic effec on gel strength, hardness, springiness, gumminess and chewiness, which are better than that of whey protein isolate or albumen; however, no significant effect on solubility. On the other hand, it is show that the network structures of albumen always condense into a small ball and dense crosslinking of aggregate; however, that of whey protein isolate condenses into chunks and less crosslinking of aggregate. While the network structures of compound protein powder is between the network structures of albumen and whey protein isolate.(3) Functional properties of whey-soybean protein composite blendsIt is estimated that the compound powders of whey protein isolate and soybean protein isolate show antagonistic effect on foam ability; while synergistic effect on gel strength, hardness, springiness, gumminess and chewiness; however, the compound powders have no significant effect on solubility. It is found that the Ordering and homogeneity of the structures of compound protein powder of whey protein isolate and soybean protein isolate is between the network structures of isolated soy protein and soybean protein isolate.(4) Build regression models on foamability、foam stability、gel property of three different proteins and determine equations of liner regression between raw material and three properties: Foaming capacity y=325.4x1+94.3x2+102.2x3-293.9x1x2+98.2x2X3-248.8x1x3+855.7x1x2X3Water losing rate y=17.8x1+76.1x2+77.6x3-1.2x1x2-52.2x2X3-0.6x1x3-185.5x1x2x3Gel strength y=-77x1+1596x2+861x3+1144x1x2+196x2X3+3943x1x3+730x1x2X3In these above results, mixed protein have significant impact on single protein’s characteristics, mutual reaction of proteins’ ingredients are not simple superposition effects, but some synergy or antagonized effects. This indicates that mixed protein, as a natural and harmless methods will be more widely used in food industry, these results can also provide theory fundaments and technique supports for mixed protein powder.