高密度二氧化碳对酪蛋白结构及物理特性的影响

The Effect of DPCD on the Structure and Physical Properties of Casein

以酪蛋白为对象,研究高密度二氧化碳(dense phase carbon dioxide,DPCD)处理压强、时间、温度对酪蛋白品质的影响规律。采用圆二色谱和表面疏水性表征酪蛋白二、三级结构变化;通过溶解度、粒径、乳化性及表观黏度反映DPCD对酪蛋白界面特性、流动行为等物理特性的影响。结果表明:当处理温度与时间恒定时,增大DPCD处理压强,导致酪蛋白二级结构中更多α-螺旋和无规则卷曲转化为β-折叠,提高其表面疏水性并降低酪蛋白溶解度和表观黏度,同时使其粒径先减小后增大,乳化性先降低后轻微升高;处理时间对酪蛋白的影响规律与压强相似,而对其表观黏度影响不显著。当处理压强与时间恒定时,提高DPCD处理温度,可引起酪蛋白二级结构相反的变化,使其表面疏水性先升高后下降,同时引起其溶解度、乳化性降低和粒径急剧增大。结论:DPCD处理压强、时间、温度变化均可影响酪蛋白结构和物理特性,其中温度影响最为显著。选择低温处理条件可有效保护乳制品在DPCD处理后的品质。

Dense phase carbon dioxide(DPCD)is a promising non-thermal sterilization technology.In order to explore the effect of DPCD on the quality of casein in dairy products.We took casein as the research object and studied the effect of DPCD treatment pressure,time and temperature on the structure and physical properties of casein.The secondary and tertiary structure changes of casein are characterized by circular dichroism and surface hydrophobicity.And the effect of DPCD on the physical properties of casein such as interface properties and flow behavior are reflected by solubility,particle size,emulsibility and viscosity.The results show that when the treatment temperature and time are constant,increasing the DPCD treatment pressure will cause moreα-helices and random coils to be converted intoβ-sheets in the secondary structure of casein,improve its surface hydrophobicity,and reduce its solubility and apparent viscosity,at the same time make its particle size and emulsibility first decrease and then increase.The effect of treatment time on casein is similar to pressure,but its effect on apparent viscosity is not significant;When the treatment pressure and time are constant,increasing the DPCD treatment temperature may cause the opposite change in the secondary structure of casein,and make its surface hydrophobicity increase first and then decrease,at the same time cause the reduction of its solubility,emulsibility and increase its particle size sharply.In summary,the pressure,time,and temperature of DPCD treatment affect the structure and physical properties of casein,among which temperature has the most significant effect.Therefore,the low temperature treatment conditions can effectively protect the quality of dairy products after DPCD treatment.