In this paper, pea protein isolate is used as a raw material for dry grinding treatment to explore the effect of dry grinding treatment on the functional properties of pea protein isolate. It also reveals the relationship between the structure and functional properties of pea protein isolate during the grinding process. The focus is on the mechanism of dry grinding on the emulsification and acid-induced gelation of pea protein isolate. The main conclusions are as follows:
(1) Dry grinding had significant effect on the structure of pea protein isolate. Among them,the random coils in the secondary structure increased and the structure tended to be disordered,and the hydrophobic groups in the tertiary structure were exposed. After grinding, the surfaceof the protein became rough, and there were a large number of aggregates to form layered irregular structure, and the texture became loose. After grinding, the particle size of the protein decreased and the dispersion was uniform, but the protein formed aggregates during the grinding process.
(2) Dry grinding had varying degrees of influence on the functional properties of pea protein isolate. Dry grinding treatment significantly improved the solubility, water retention, oil retention, foaming and foam stability of pea protein isolate. When the grinding time was 7.5 min, the water retention was increased by 37.4%, the foaming property was increased by 20.83%, and the oil retention and solubility were also significantly improved.
(3) Dry grinding changed the emulsifying properties of pea protein isolate. The emulsion prepared by dry grinding for 5-7.5 min from pea protein separation exhibited agglomeration and flocculation. Zeta potential and surface tension tended to decrease, and the oil droplet size increased. The emulsion prepared by dry grinding for 10-15 min from pea protein separation could significantly reduce the particle size of oil droplets and the flocculation of the emulsion.
The protein adsorbed on the interface was close to saturation, the Zeta potential and surface tension were increased, and the stability of the emulsion was improved. At the same time, the grinding treatment reduced the influence of temperature on the emulsion.