Abstract:

Rape bee pollen protein was hydrolyzed with Alcalase 2.4L, and the change in degree of hydrolysis (DH) during hydrolysis was determined by pH stat method, OPA method or TNBS method, and differences in determination results were analyzed. DH derived from 118 min hydrolysis was measured by pH stat, OPA and TNBS methods to be 4.7%, 13.4% and 6.6%, respectively. Due to lower absorbance at 340 nm of the products of reaction among OPA reagent, lycine, cysteine and lysine, the determination by OPA method gave a lower DH. Unstable reaction between TNBS reagent and ε-NH2 was likely to due to the presence of certain luminescent substances generated from TNBS reagent. In the case of lower DH, the change in average degree of dissociation of α-NH2 groups could be neglected. In conclusion, pH stat method is a more accurate method than the two other ones.

Key words: rape bee pollen, bee pollen protein, degree of hydrolysis, OPA method, pH stat method, TNBS method