高压微射流处理对米谷蛋白热聚集体性质的影响

Effect of High Pressure Micro?uidization Treatment on the Properties of Thermal Glutelin Aggregates

天然大米谷蛋白通过酸法热处理(pH 2.0、90℃、30 min)制备纤维化热聚集体,采用高压微射流处理(35、70、105、140 MPa),以未经热处理和高压处理的样品为对照,对样品形貌、粒径、ζ电位、表面疏水性、巯基含量、热特性、流变性、乳化性能及二级结构组成等进行比较分析,探究高压处理对其理化特性的影响。结果表明:高压微射流处理后,样品结构变得疏松,粒径增大,由(146.93±1.04)nm增加到(184.77±4.82)nm;总游离巯基含量先增加后减小,乳化活性指数及乳化稳定性指数先上升后下降,在70 MPa时达到最大,分别为(30.08±0.75)m^2/g和(150.58±2.03)min;ζ电位和表面疏水性的变化较小;高压微射流处理对热稳定性和表观黏度均有一定影响;二级结构组成α-螺旋、β-转角含量增加,β-折叠含量减少。低压会使蛋白进一步聚集,较高的压力则会使其解聚;70 MPa处理的样品具有较好的乳化特性和热稳定性。

In this study,natural rice glutelin was modified by acid-heat treatment(pH 2.0,90℃for 30 min).As a result,we obtained fibrous protein aggregates,and we further treated the protein aggregates by high pressure microfluidization(HPM)at different pressure levels(35,70,105 and 140 MPa).The samples without heat or high pressure treatment were used as a control.The effects of high pressure treatment on physicochemical properties were investigated by comparing the morphology,particle size,ζpotential,surface hydrophobicity,sulfhydryl content,thermal properties,rheological properties,emulsifying properties and secondary structure of the treated and untreated samples.The results showed that after HPM treatment,the structure of the protein aggregates became loose,and the particle size increased from(146.93±1.04)to(184.77±4.82)nm.The total sulfhydryl content increased first and then decreased,and so did the emulsifying capacity and emulsion stability,at 70 MPa reaching a maximum of(30.08±0.75)m^2/g and(150.58±2.03)min,respectively.Small changes were observed inζpotential and surface hydrophobicity,but thermal stability and apparent viscosity were affected by HPM treatment.The secondary structures ofα-helix andβ-turn increased,whileβ-sheet reduced.Lower pressure could result in further protein aggregation,and higher pressure could lead to depolymerization.The sample modified by 70 MPa treatment had good emulsifying properties and thermal stability.