Impact of selected process parameters on solubility and heat stability of pea protein isolate

Pea protein isolate (PPI) is considered a promising substitute for commonly used protein ingredients of animal origin. Its application in food industry is limited by lack of scientific knowledge on functional properties including solubility. PPI dispersions adjusted to concentration (4% or 8% w/w protein), pH (6.8 or 7.5) and ionic strength (IS non-adjusted, 50 or 100 mM) were subjected to two industrially applied heat treatments of 140 degrees C for 4 s (ultra-high temperature, UHT) or 121 degrees C for 2.8 min. Solubility and heat stability varied depending on pH, IS, protein concentration and heat treatment. Both 4% and 8% PPI dispersions demonstrated high solubility (> 97%) at pH 7.5 and IS non-adjusted either non-heated or 121 degrees C/2.8 min heated conditions. They also showed high heat stability (> 92%) after 121 degrees C/2.8 min treatment. UHT generally resulted in low solubility and heat stability regardless of solution conditions. Treatment at 121 degrees C/2.8 min mostly formed soluble protein aggregates through covalent (thiol-disulphide) interactions while UHT mainly produced non-soluble aggregates through non-covalent interactions. Manipulation of solution conditions and optimization of heat treatments could be a promising approach to improve solubility and heat stability of pea proteins.