牦牛乳酪蛋白琥珀酸铁的制备及其结构表征

Preparation and Structural Characterization of Ferric Succinate from Yak Cheese Protein

为了充分利用牦牛乳资源,以牦牛乳酪蛋白为原料,采用响应面分析法确定牦牛乳酪蛋白的最佳酰化条件,制备高质量、生物利用率好的蛋白琥珀酸铁制品;采用傅里叶红外光谱、粒径分布、扫描电子显微镜、氨基酸组成、体外模拟消化等手段对制品进行结构表征。结果表明:牦牛乳酪蛋白最佳酰化工艺参数为:酪蛋白与丁二酸酐质量比2∶1,丁二酸酐分5次加入,pH 9,反应温度48℃,反应时间50 min,在此条件下酰化率达到93.27%,含铁量8%,螯合率93.03%。傅里叶红外光谱测定结果显示:蛋白琥珀酸铁与酪蛋白的吸收峰存在差异,酰化蛋白中铁离子与羧基、氨基形成配位键。用激光粒度分布仪测得蛋白琥珀酸铁粒径更大,证实形成螯合物。扫描电子显微镜分析表明样品表面光滑,结构紧密。通过测定蛋白琥珀酸铁的蛋白含量及氨基酸组成,得出蛋白琥珀酸铁较酪蛋白蛋白质损失28.12%。酪蛋白与蛋白琥珀酸铁中Glu、Asp和Pro含量较高,其中Glu和Asp是形成螯合物的关键氨基酸,且生物利用率优于无机盐。本研究结果可为蛋白琥珀酸铁制备以及结构表征提供参考。

In order to make full use of yak milk resources,using yak milk casein as the raw material,the response surface analysis method was adopted to determine the optimal acylation conditions of yak milk casein and prepare high-quality and good bioavailability ferrous succinylprotein products.The structure of the products was characterized by means of Fourier transform infrared spectroscopy,particle size distribution,scanning electron microscopy,amino acid composition,and in vitro simulated digestion.The results showed that the optimal acylation process parameters of yak milk casein were as follows:The mass ratio of casein to succinic anhydride was 2∶1,succinic anhydride was added five times,pH value was 9,the reaction temperature was 48℃,the reaction time was 50 min.Under these conditions,the acylation rate reached 93.27%,the iron content was 8%,and the chelation rate was 93.03%.The determination results of Fourier transform infrared spectroscopy showed that there were differences in the absorption peaks between ferrous succinylprotein and casein,and the iron ions in the acylated protein formed coordination bonds with carboxyl groups and amino groups.The particle size of ferrous succinylprotein was measured to be larger by the laser particle size distribution analyzer,confirming the formation of the chelate.The analysis by scanning electron microscope indicated that the surface of the sample was smooth and the structure was compact.By determining the protein content and amino acid composition of ferrous succinylprotein,the results showed that the protein loss of ferrous succinylprotein compared to casein was 28.12%.Among them,Glu,Asp,and Pro had the higher contents in casein and ferrous succinylprotein.Glu and Asp were the key amino acids for forming chelates,and the bioavailability was better than that of inorganic salts.The results of this study can provide a reference for the preparation and structural characterization of ferrous succinylprotein.