Physicochemical and gel properties of pumpkin seed protein: a comparative study

The physicochemical properties and heat-induced gel properties of pumpkin seed protein isolates (PSPI) were explored and compared with soybean protein isolate (SPI) and pea protein isolates (PPI). These plant proteins were subjected to ultrasound, acid or alkaline treatment (pH 3 or 11). The content of amino acids and subunit composition were different in PSPI compared with SPI and PPI. Rheological and textural experiments showed that native PSPI had the highest gel strength among the three proteins. This was due to the high hydrophobicity of PSPI and the filling effect of insoluble particles in the protein solution. PSPI had a more pronounced improvement in gel properties after ultrasound or alkaline treatment compared with SPI and PPI, which was due to the increased surface hydrophobicity, increased solubility and reduced particle size of the proteins. The acid treatment induced insoluble aggregates increased the protein particle size, and decreased the protein solubility, resulting in a negative effect on the PSPI protein gel. Therefore, it can be concluded that PSPI has better heat-induced gelation than SPI and PPI and can be used as a substitute for SPI and PPI in the food industry.