The effects of dephenolization on structural, physico-chemical and functional properties of sunflower protein isolate obtained from de-oiled sunflower cake were investigated. Proximate analysis showed that the moisture and crude protein content for sunflower dephenolized protein (SPI-DP) increased by 59 and 9% compared to the natural sunflower protein (SPI–N) samples, while the ash content and phenolic compounds decreased 53 and 98%, respectively. Powder of SPI-DP had a yellowish color and analysis using scanning electron microscopy showed a rough and spongy surface compared to SPI-N. The isoelectric point of SPI-N and SPI-DP were observed at pH 4.37 and 4.82, respectively. Analysis of mineral composition showed a lowered amount of minerals (except for Se and Sr), as a result of phenolic removal. Secondary structures of the protein did not change but lower hydrophilicity was observed after phenolic removal using Fourier transform infrared spectroscopy. No difference was observed using differential scanning calorimetry on the glass transition and denaturation temperatures. Higher values for foam capacity and foam stability were observed for SPI-DP compared to SPI-N. Interfacial rheological measurements showed that structure strength at the air/water interface increased after phenolic removal.
- de-phenolized sunflower protein
- Foaming properties
- Helianthus annuus
- Interfacial rheology
- Sunflower cake