Effects of Ultrasound Treatment on Emulsifying Properties of Pea Protein Isolates Obtained from Four Different Pea Flour Varieties

This study investigated the extraction and colloidal properties of pea protein isolates (PPIs) from four pea cultivars produced in a southern region in Italy. The control PPIs (C-PPIs) were obtained via an alkaline extraction and isoelectric precipitation method and then subjected to ultrasound treatment (US) to yield US-PPIs. The effects of cultivars and sonication on the physicochemical characteristics and emulsifying property of the PPIs were studied. Fourier-transform infrared (FTIR) spectroscopy, colorimetric measurement, dynamic light scattering (DLS), and confocal laser scanning microscopy (CLSM) were applied to characterize the samples. DLS results showed that C-PPIs displayed smaller particle sizes (8.86-15.9 µm) in comparison to US-PPIs (15.8-66.5 µm). DSC data showed that US-PPIs had improved thermal stability compared to control PPIs. FTIR analysis detected differences in the protein secondary structure of the various cultivars and between the native and US-PPIs. Emulsion stability studies indicated that emulsions stabilized with C-PPIs exhibited lower droplet sizes, implying improved stability in comparison to emulsions stabilized with US-PPIs. In conclusion, PPIs can be successfully extracted from different cultivars and applied as a natural emulsifier.