High-Pressure Effects on Selected Properties of Pea and Soy Protein Isolates

Abstract

The use of vegetable proteins has been the focus of research efforts to develop new products and/or to replace other sources of protein. Ergo, there is a need to assess the effects of new processing technologies on this type of protein. This work evaluated the influence of high-pressure processing (HPP) (pressure: 200, 400 and 600 MPa; holding time: 5, 10 and 15 min) on selected properties of pea (PPI) and soy (SPI) protein isolates at three pH values (6, 7 and 8). SPI presented a higher percentage of soluble proteins than PPI, still, HPP increased protein solubility of both isolates. This effect was more pronounced on SPI, particularly at pH 7 and 8, where the percentage of soluble proteins almost tripled under some HPP conditions. Similarly, the surface hydrophobicity also increased with HPP for proteins from both sources, increasing, in general, with increasing pressure and holding time. On the contrary, the content of free sulfhydryl groups generally decreased with HPP for proteins from both sources, suggesting a complex balance between protein unfolding and further aggregation under certain conditions. The effects of HPP on the emulsifying properties of the protein isolates were dependent on pH, pressure, holding time and whether the soluble or total fraction of the protein isolates were used.

Keywords

• protein isolates
• pea
• soy
• high-pressure processing
• surface changes
• emulsifying activity