Comparison of the pH-stat, TNBS and Formol- titration Methods for Quantification of Degree of Hydrolysis of Walnut Protein Isolated Hydrolysate
The pH-Stat, formol-titration and 2, 4, 6trinitrobenzenesulphonic acid (TNBS) were compared to determine the degree of hydrolysis (DH) of walnut protein isolate (WPI) hydrolysates with Alcalase 2.4L, Flavourzyme and Protamex respectively. It was shown that the pH-Stat DH values of hydrolysates by Alcalase 2.4L were similar to that by TNBS, whereas formol-titration DH values are lower. As WPI was relatively rich in proline, an unstable compound generated during the reaction between the proline and formaldehyde, which led to the lower DH values by formol-titration method. Poor correlation was observed among the three methods for DH values in Flavourzyme and Protamex hydrolysates, and the DH values were both lower obtained by pH-stat method. It is well known that Flavourzyme and Protamex are rich in exopeptidase activities, resulting in an overestimation of a used in the calculation of DH by the pH-stat method. TNBS was not affected by the type of enzymes which were used to generate the WPI hydrolysates. It deemed that the TNBS method was more reliable for DH estimation in the WPI hydrolysates.
walnut protein isolate degree of hydrofysis(DH) pH-Stat method TNBS method formol-titration method
Zhen-Bao Zhu Hui-Jiang Zhou Jian-HuaYI
College of Life Science & Engineering Shaanxi University of Science & Technology Xian, China
国际会议
哈尔滨
英文
650-653
2012-06-16（万方平台首次上网日期，不代表论文的发表时间）