脂对浓缩乳蛋白溶解稳定性的影响

以浓缩乳蛋白（MPC）为研究对象，通过向MPC中加入不同熔点的乳脂模拟物来制备含脂浓缩乳蛋白模型体系，旨在研究脂对储藏过程中MPC溶解稳定性的影响。分别考察了模型含脂乳粉在45 ℃（相对湿度23 %）和35 ℃（相对湿度11 %）下分别储藏30 d和60 d后的溶解度变化，通过讨论储藏过程中脂质氧化、蛋白氧化、蛋白不溶物的形成等对MPC溶解度下降的分子机制进行了探索。研究结果表明，虽然不同熔点的脂在储藏初期时对MPC溶解度的下降具有一定的影响，但是脂质氧化和蛋白氧化都不是MPC在储藏过程中溶解度下降的关键因素，经由氢键、二硫键和疏水相互作用所形成的酪蛋白不溶物才是影响MPC溶解度的主要原因
This study was focus on the effect of lipid on the protein solubility of milk protein concentrate，which lacks of intensive study now. A model system was established using fatty acid methyl ester with different melting points including methyl laurate and methyl myristate. The spray dried milk powder prepared with various lipids was storage at 45 ℃（RH 23%） for 30 days and at 35 ℃（RH 11%） for 30 days，respectively. The changes in the powder solubility under different conditions were studied and the mechanism of solubility decrease was explored. The effect of lipid on protein solubility was insignificant. The most prominent determinant for solubility decrease was related neither to lipid oxidation nor to protein oxidation. The interaction between caseins caused insoluble aggregates formation during storage，which decreased the protein solubility. The main driving forces for protein aggregation were in the prefer orders of hydrogen bond > disulfide bond > hydrophobic interaction