Emulsifying and foaming properties of gluten hydrolysates with an increasing degree of hydrolysis: Role of soluble and insoluble fractions

Gluten solubility was improved by enzymatic proteolysis at moderate acidic pH level. Reversed-phase HPLC analysis of gluten hydrolysates with a degree of hydrolysis (DH) in the range of 0-5% showed that both hydrophilic and h ydrophobic soluble peptides were released. Emulsifying and foaming properti es of hydrolysate dispersions at 3.75 mg/mL decreased with the increasing D H at all pH levels and salt conditions investigated. On the other hand, the soluble fractions separated from those hydrolysate dispersions exhibited g ood functional properties, independently of the initial DH. The proportion of hydrophilic and hydrophobic peptides in the soluble fractions depended a n DH, pH level, and salt concentration. Nevertheless, these soluble fractio ns were characterized by an excellent capacity to stabilize both oil-water and air-water interfaces.