OptimizatiOn Of prOtein extractiOn frOm sunflOwer meal prOduced in Bulgaria

IVANOVA, P., V. CHALOVA, L. KOLEVA, I. PISHTIYSKI and M. PERIFANOVA – NEMSKA, 2012. Optimization of protein extraction from sunflower meal produced in Bulgaria. Bulg. J. Agric. Sci., 18: 153-160 Sunflower meal obtained after defatting of sunflower seeds is a by-product, which has the potential to serve as an attractive source for the preparation of protein isolates for food purposes. Protein extraction depends on many factors. Sunflower proteins are commonly extracted under alkaline conditions due to their low solubility in mildacidic and neutral conditions. However, the alkaline medium favors phenol-protein interactions leading to formation of dark-colored products, which are inappropriate for human consumption. The aim of this research was to identify the optimal conditions for protein extraction from sunflower meal produced in Bulgarian oil factory by investigating the effect of NaCland sunflower meal concentrations, pH, temperature, and extraction time on protein yield. It was established that increases of pH in the range from 2 to 10 constantly enhanced protein extractability. At pH 5-7, the protein extraction was dependent on NaCl concentrations. Extracting proteins with 7.5% -12.5% NaCl solutions and temperature 40oC obtained greatest protein yields at pH6. The utilization of 2.5% sunflower meal appeared to be the most appropriate for the achievement of maximum protein extraction. The incremental increases of the sunflower meal from 5% to 15% did not substantially modulate the protein yields. The most efficient extraction occurred during the first 15 min but maximum protein yields were obtained after 60-75 min of extraction. Our study demonstrated that by extracting 10% sunflower meal with 10% NaCl, at pH6 and 40оС for the period of 60-75 min, a protein yield greater than 50% at diminished protein-phenol interaction could be achieved.