Influence of high isostatic pressure on structural and functional characteristics of potato protein

• Potato protein solubility was less affected by pressure in comparison to heat treatments.
• Minor structural changes in the soluble protein fraction were determined after pressure treatments.
• Pressure induced aggregates were stabilized via hydrogen bonds and hydrophobic interactions and differed from heat induced aggregates.
• Increased foam stability due to pressure could not be preserved for a long time.

Potato protein possesses promising nutritional and techno-functional properties, but distinct heat sensitivity. Therefore, the potential of high isostatic pressure as an alternative preservation and modification method was investigated. Pressures of 200, 400 and 600 MPa were applied at isothermal conditions of 20 and 40 °C to dispersions made of potato protein concentrate and isolated patatin for dwell times of 10 min. Process induced changes in solubility, foaming properties and selected structural characteristics were compared to results of pure thermal treatments from 20 to 80 °C. Potato protein solubility in neutral solutions made of concentrate was reduced to 21% after heating to 70 and 80 °C whereas it only decreased to 74% after pressurization at 600 MPa. Processing of isolated patatin at pH 6 and pH adjustment from 7 to 6 after processing reduced protein solubility to 12% for heat treatments and to 55 and 89%, respectively, for pressure treatments indicating different denaturation or aggregation mechanisms. Hydrogen bonds and hydrophobic interactions were involved in pressure induced aggregation, whereas aggregates formed during heat treatments were primarily stabilized by hydrophobic interactions. The surface hydrophobicity of soluble protein increased by factor 2.5 to 4.5 after heat treatments and by factor 1.3 at maximum after pressure treatments. High pressure processing provides therefore a good alternative to conventional heat pasteurization as initial potato protein quality may be preserved to a higher extent. Foam stability was increased to 177% by pressure treatments, but this modification was not long-term stable. Applying high pressure with the aim of a functional modification therefore requires further investigations.