为了探究三偏磷酸钠(sodium trimetaphosphate，STMP)对植物蛋白功能和结构的影响机制，采用油菜籽粕为原料提取了油菜籽分离蛋白(rapeseed protein isolate，RPI)，以不同用量的 STMP 对其改性，通过 XPS、31PNMR、FT-IR、DSC，结合P含量、表面疏水性、巯基及二硫键含量变化，表征了改性后油菜籽分离蛋白(modified rapeseed protein isolate，MRPI)的微观结构和功能性。在此基础上，通过对不同样品进行了主成分分析(principal component analysis，PCA)以进一步了解RPI结构和理化特性之间的关系。研究结果表明:STMP与RPI分子中的―OH发生化学结合，与RPI相比MRPI的P含量增加了 1。38 mg/g;同时β-转角和无规卷曲的占比均有所增加。PCA结果表明:RPI的交联程度显著影响其持水持油性、热变性温度和乳化能力，而乳化稳定性则与α-螺旋、β-折叠的比例正相关。此实验结果有助于阐明STMP对植物蛋白功能性的影响机制，为赋予植物蛋白特定的功能提供一定的理论基础。
Effect of Sodium Trimetaphosphate Modification on The Structure and Functionality of Rapeseed Protein Isolate
To investigate the effect of sodium trimetaphosphate(STMP)on the functionality and structure of plant proteins,the degreased rapeseed meal was chosen as raw material,the rapeseed protein isolate(RPI)was extracted.And then modified RPI(MRPI)was prepared using STMP as crosslinking agent.The effect of STMP on the functional and molecular structure of RPI were investigated by XPS,31PNMR,FT-IR,DSC,combined with the changes of phosphorus content,surface hydrophobicity,sulfydryl group and disulfide bond content.Furthermore,principal component analysis(PCA)was then carried out to understand the relationship between the structure and physicochemical properties.The results show that STMP reacted with the ―OH in RPI molecules,and the phosphorus content of MRPI increased by 1.38 mg/g compared with RPI.The proportions of β-folding and random curl in the modified product molecules increased.PCA results show that the degree of cross-linking of RPI significantly affected its water and oil-holding properties,thermal denaturation temperature and emulsification capacity,whereas the emulsification stability was positively correlated with α-helix and β-sheet proportion.The results are helpful to elucidate the mechanism between STMP and plant protein.And the findings can provide some theoretical foundations in selecting desired properties to achieve more appropriate application.
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