Decrease of the Soybean Glycinin Digestibility in Excess Denaturation; Effect of Refolding

Abstract

The digestibility of denatured glycinin with various denaturants such as urea, GuHCl and SDS, and heat treatment, was studied by a pH -stat method. It increases with increasing concentration of the denaturants and heating temperature. However, further addition of the denaturants and 120°C heating caused decrease of digestibility. In urea denaturation, optical measurements indicate that conformation of the protein appreciably refolds after the removal of the denaturant. Gel filtration analyses also indicate the partial refolding of the structure of the protein. Therefore, the refolding of the protein may play an important role in the decrease of the digestibility. However, the structural differences of denatured glycinin from native one and reasons of the decrease of the digestibility can not be revealed yet.