Extraction of protein from sunflower Deoiled cake

Sunflower seeds (Helianthus annuus L.) are among the world’s most important oilseeds. The techno functional properties of sunflower proteins are comparable with those of soy and other leguminous proteins. Sunflower meal is a source of high quality protein. Preliminary experiment on extraction of protein was carried out with sodium chloride (NaCl concentration of 1-3 mol/L) using 1.0 N NaOH for pH adjustment. Three levels of pH (6-8), extraction temperature (15-45 °C), NaCl concentration of 1-3 mol/L and ratio of sunflower meal to solvent (10-20 w/v) were selected and evaluated to study the effect of extraction process variables on protein isolate yield (% weight) and protein content (%). The results revealed that the protein isolate yield was less than 15% and were also dark in colour. Hence, the treatments were modified by changing NaCl concentration to 8.0% minimum to 12.0% maximum and Meal % (8 to 12%). The temperature (30 °C) and extraction time (30 min) were kept constant for all treatments for better extraction. Extracted protein was precipitated at pH 4.5 with 1.0 N HCl, and collected by centrifugation at 5000 rpm for 30 mins. The sunflower protein isolates (SPI) were washed with water and adjusted to the pH of precipitation, and again re-centrifuged. The washed SPI was adjusted to pH 7 with NaOH prior to being dried. In conclusion, response surface methodology technique was found to be very useful in determining the optimization conditions for extraction of protein isolate. The optimum protein extraction was achieved by extracting the cake at the extraction conditions of: pH-9, NaCl % -9, Meal % - 10.