物理复合改性对SPI保水保油性和结构特性的影响

Effect of Physical Compound Modification on Water and Oil Retention and Structural Characteristics of SPI

目的通过高压均质和热处理对SPI(Soy Protein Isolate)进行改性,探究SPI的保水保油性和结构变化,以期提高SPI在食品加工中的应用。方法以大豆分离蛋白为原料,通过采用响应曲面法优化高压均质协同热处理SPI改性技术,并研究不同条件的高压均质-热处理方式对SPI保水保油性和结构特性的影响。结果在先高压后加热的复合改性方式下获得的SPI保水保油性最好,得到了响应面优化的最佳工艺参数,即均质压力为108 MPa、加热温度为93℃、加热时间为22 min。改性后的SPI(Modified-SPI,M-SPI)保水性、保油性分别为4.29 g/g和1.74 mL/g。结构表征结果显示,高压均质协同热处理显著改变了SPI的结构,与天然态SPI(Nature-SPI,N-SPI)相比,M-SPI的游离巯基、暴露巯基、二硫键含量及表面疏水性均显著增大(P<0.05),分别为8.83,7.42,22.78μmol/g和1104;微观形貌显示,与N-SPI相比,M-SPI颗粒表面细致光滑、粒径变小且大小均一、分布均匀。结论SPI经过高压均质和热处理后,具有良好的保水保油性,研究改性后SPI的结构变化可为其保水保油性的提高提供理论依据。

The work aims to modify SPI(soy protein isolate)by high pressure homogenization and heat treatment and study the changes in water and oil retention and structure of SPI,so as to improve the application of SPI in food processing.The SPI was used as raw material to optimize the SPI compound modification technology of high pressure homogenization and heat treatment by Response Surface Methodology(RSM)and study the effect of high pressure homogenization-heat treatment under different conditions on the water and oil retention and structural characteristics of SPI.The best water and oil retention of SPI was obtained by the compound modification method of high pressure followed by heating.The best process parameters for RSM were as followed:homogeneous pressure of 108 MPa,heating temperature of 93℃and duration time of 22 min.The water and oil retention of modified SPI(M-SPI)was 4.29 g/g and 1.74 mL/g respectively.The structural characterization results showed that the structure of SPI was significantly modified by the high pressure homogenization cooperated with heat treatment.Compared with natural-SPI(N-SPI),the content of free sulfhydryl,exposed sulfhydryl,disulfide bond and surface hydrophobicity of M-SPI were significantly increased(P<0.05)to 8.83μmol/g,7.42μmol/g,22.78μmol/g and 1104 respectively.The microscopic morphology showed that compared with N-SPI,the surface of M-SPI particles was fine and smooth,the particle size became smaller and the size and the distribution were uniform.After the cooperation of high pressure homogenization and heat treatment,SPI has good water and oil retention,and the structural changes after modification can also provide theoretical basis for the improvement of water and oil retention.