胶束化和碱溶酸沉提取羽扇豆蛋白的物化特性

Physicochemical Properties of Lupin Proteins Extracted by Micellization or Alkali Dissolution Followed by Acid Precipitation

利用胶束化和碱溶酸沉2种提取方法从羽扇豆中提取羽扇豆蛋白,并对2种方法提取羽扇豆蛋白的物化特性进行研究。结果表明:羽扇豆蛋白分子质量主要集中在18~90 kDa之间,是由多种分子质量的蛋白组成。碱溶酸沉提取羽扇豆蛋白的氨基酸总含量(66.2%)显著(P<0.05)高于胶束化提取羽扇豆蛋白的氨基酸总含量(27.8%)。2种提取方法提取羽扇豆蛋白的等电点pI接近5.0。胶束化提取羽扇豆蛋白的持水性显著(P<0.05)高于碱溶液酸沉法提取的羽扇豆蛋白,而持油性无显著差异(P>0.05)。碱溶酸沉法提取羽扇豆蛋白的起泡性在pH 2.0~6.0之间显著减小,在pH 6.0时起泡性最低,其泡沫稳定性的变化趋势与其起泡性类似。而胶束化提取羽扇豆蛋白的起泡性受pH值的影响不显著(P>0.05)。胶束化提取的羽扇豆蛋白在pH 4.0时乳化性最小,然后随pH值的升高蛋白乳化活性也随之增加,2种提取方法所提羽扇豆蛋白在pH 10.0时乳化活性最高。碱溶酸沉法提取的羽扇豆蛋白在pH 4.0时溶解度最小,而随着pH 4.0~10.0的增加,蛋白溶解度迅速增加。而胶束化提取羽扇豆蛋白的溶解度随pH 2.0~10.0的升高也逐渐增大。该研究为羽扇豆蛋白在食品工业中的开发与应用提供一定理论支持。

In this study,lupin proteins were extracted from lupin seeds by two different methods,namely,micellization and alkali dissolution followed by acid precipitation,and their physicochemical properties were evaluated.The molecular mass distribution of lupin proteins was mainly in the range of 18–90 kDa and consisted of proteins with various molecular masses.The total amino acid content of lupin proteins extracted by sequential alkali dissolution and acid precipitation(66.2%)was significantly higher(P<0.05)than that obtained by micellization(27.8%).The isoelectric point(pI)of lupin proteins extracted by the two extraction methods was close to 5.0.The water-holding capacity of lupin protein extracted by micellization was significantly higher(P<0.05)than that obtained by alkali dissolution followed by acid precipitation,but there was no significant difference(P>0.05)in oil-holding capacity between the two methods.The foaming capacity of lupin protein extracted by sequential alkali dissolution and acid precipitation decreased significantly at pH 2.0–6.0,and was the lowest at pH 6.0,and the trend of foam stability was similar to that of foaming capacity.However,pH had no significant effect(P>0.05)on the foaming ability of lupin protein extracted by micellization.The emulsifying capacity of lupin protein extracted by micellization was the lowest at pH 4.0,and then increased with the increase of pH.The emulsifying capacity of lupin proteins extracted by the two extraction methods was the highest at pH 10.0.The solubility of lupin protein extracted by alkali dissolution followed by acid precipitation was the lowest at pH 4.0,and increased rapidly with the increase of pH from 4.0 to 10.0.The solubility of lupin protein extracted by micellization increased with the increase of pH from 2.0 to 10.0.The results of this study can provide theoretical and technical support for the development and application of lupin proteins in the food industry.