Optimization of Enzyme Assisted Alkaline Extraction of Sunflower (helianthus Annuus L.) Protein for Alternative Isolate Production

Abstract

This research focused on the effect of extraction time (60–120 min), enzyme/substrate ratio (0.05–0.4 %) temperature (37.5°C) on enzyme assisted alkaline protein extraction efficiency from non-dehulled sunflower meal, which is a by-product of oil production. 4 commercial enzymes were studied and the highest protein yield (92 %) was obtained by ultrafiltration of the enzymatic hydrolysates through a membrane (selectivity 81.4%) followed by the isoelectric precipitation (pH 4.5) and vacuum drying. The protein yield was found 92.85% at the optimized condition of enzyme assisted alkaline extraction: temperature 37.5 °C, 60 min, and enzyme/substrate ratio of 0.2%. Compared to alkaline extraction with 0.25% NaOH and no enzyme addition, the protein yield has increased by 31% due to the mild extraction conditions. Determined physicochemical properties of the obtained protein isolate: high protein content (92.85% d.b) as well as high solubility (95.0% at pH 7.5) reflect the unique characteristics of the product. However, the process requires further optimization because of the green colour of the isolate, which limits its application in the food industry.