Emulsifying and Foaming Properties of Commercial Yellow Pea (Pisum sativum L.) Seed Flours

Commercial yellow pea seed flours prepared by a patented wet-milling process and pea protein isolate (PPI) were analyzed for emulsifying and-foaming properties at pH 3.0, 5.0, and 7.0 and compared to soybean protein isolate (SPI). PIPI and, SPI formed emulsions with significantly smaller (p < 0.05) oil droplet sizes, 16-30 and 23-54 mu m, respectively, than flours that primarily contained fiber such as Centara III and IV, or those that consisted mainly of starch: Centu-tex, Uptake 80 and Accu-gel. PPI was a better emulsifier than SPI at pH 7.0, and a better foaming agent at pH 3.0 and pH 7.0, although foaming capacity varied with sample concentration. Centu-tex and Uptake 80 have exactly the same chemical composition, but the latter has a much smaller flour particle size range, and had significantly smaller (p < 0.05) emulsion oil. droplets. Incorporation of pea starch into SPI emulsions produced a synergistic effect that led to significant increases (p < 0.05) in emulsification capacity (reduced emulsion oil droplet size) when compared to SPI or starch alone. These results showed that PPI had generally significantly higher (p < 0.05) emulsion and foam forming properties than SPI, and that pea starch could be used to improve the quality of SPI-stabilized food emulsions.