热处理条件对驼乳乳清蛋白理化性质和功能性的影响

Effects of Heat Treatment Conditions on Physicochemical Properties and Functionality of Camel Whey Protein

乳清蛋白是乳成分中的重要成分,但在杀菌过程中,热处理会对乳清蛋白的结构和性质产生一定影响,本研究通过65℃/30 min、85℃/15 s、125℃/4 s和135℃/4 s不同加热温度处理驼乳,再将不同处理方式的驼乳进行驼脂和酪蛋白沉淀,分离出乳清蛋白,进一步探究不同热处理对驼乳乳清蛋白变性程度、理化性质和功能特性的影响。结果表明:65℃/30 min处理下驼乳乳清蛋白的浊度(0.14)、粒径(0.24μm)、Zeta电位(-9.54 mV),溶解性(24.57 mg/mL)、二级结构中α-螺旋相对含量最高(31%)且β-转角(13%)和无规则卷曲相对含量(19%)最低,持水性、起泡性、乳化性等显著增大,这表明65℃/30 min处理下乳清蛋白变性程度最小,理化性质变化不显著,且在一定程度上改善其乳化性、起泡性、持水持油等功能特性;随着温度升高,85℃/15 s处理下的驼乳乳清蛋白粒径增大至0.32μm,溶解性降低至22.34 mg/mL,但其功能性等相比于生鲜驼乳乳清蛋白有一定提升,125℃/4 s和135℃/4 s处理下导致大量乳清蛋白变性,二级结构被破坏,粒径和浊度增大、溶解性降低,功能特性变差。

Whey protein is an important component of milk,but heat treatment during sterilization has a certain impact on the structure and properties of whey protein.Therefore,this study investigated the effect of different heat treatments on the denaturation degree,physicochemical properties and functionality of camel whey protein,which was separated from camel milk heat-treated under different conditions,65℃/30 min,85℃/15 s,125℃/4 s and 135℃/4 s,after milk fat and casein precipitation.The results showed that whey protein treated at 65℃for 30 min had the highest turbidity(0.14),particle size(0.24μm),zeta potential(-9.54 mV),solubility(24.57 mg/mL),and relative content ofα-helix(31%)as well as the lowest relative contents ofβ-turn(13%)and random coil(19%);the water-holding capacity(WHC),foaming capacity and emulsifying capacity were significantly increased by the heat treatment,which indicated that 65℃/30 min treatment resulted in the smallest denaturation degree of whey protein and improvements in its functional properties such as emulsifying capacity,foaming capacity,WHC and oil-holding capacity(OHC)without significantly changing its physicochemical properties.With an increase in the heating temperature,the particle size of whey protein under 85℃/15 s treatment was increased to 0.32μm,and the solubility was reduced to 22.34 mg/mL,but its functionality was improved compared with that of raw milk whey protein.Treatment at 125℃for 4 s or 135℃for 4 s led to a large number of whey protein denaturation,destroyed the secondary structure,increased the particle size and turbidity,decreased the solubility,and worsened the functional properties.