Functional properties of plant proteins. Part 2. Selected physicochemical properties of native and denatured protein isolates from faba beans, soybeans, and sunflower seed

✍ Scribed by Schwenke, K. D. ;Prahl, L. ;Rauschal, E. ;Gwiazda, S. ;D??browski, K. ;Rutkowski, A.

• Publisher: John Wiley and Sons
• Year: 1981
• Tongue: English
• Weight: 576 KB
• Volume: 25
• Category: Article
• ISSN: 0027-769X
• DOI: 10.1002/food.19810250109

✦ Synopsis

Abstract

Functional properties — as solubility, water and oil adsorption, emulsifying capacity, emulsion activity and stability — of protein isolates from faba beans, soybeans and sunflower seed depending on the isolation process were determined.

Proteins isolated under mild conditions, it means by precipitation using dialysis or dilution of salt extracts with water, show the highest solubility, characterized by a sharp minimum of solubility at a rather narrow range of pH. An incubation of the precipitated proteins at low pH (pH 2) results in a decrease of the solubility on the alcaline and acidic part of the solubility profile.

On the contrary to the decreased solubility, the proteins denatured by acid show an increased water adsorption capacity. Depending on the kind of protein and the conditions of preparation these values can reach the manifold ones of the control. Smaller increases of oil adsorption in acid‐denatured proteins were found, too.

The emulsion activity and stability were not or only slightly influenced, but the emulsifying capacity was strongly decreased by the denaturation procedure. The emulsifying capacity was influenced by the solubility of the protein, but a strong correlation does not exist.

The high water adsorption of Promine D can be reached by the other plant proteins after denaturation. The sunflower protein showed the highest emulsifying capacity.

Increasing the pH from the isoelectric range to 7 improves all studied functional properties.