Optimization of Ultrasound Assisted Extraction of Phenolic Compounds from Sunflower Seed Cake Using Response Surface Methodology

Sunflower seed cake is a by-product of the sunflower oil industry which is a valuable source of protein for animal feed. The presence of phenolic compounds significantly affects the sunflower proteins quality to animal feeding, decreasing its commercial value. Seeking to valorize this by-product, by improving the nutritive potential of the sunflower cake and getting an extract rich in antioxidants, the present study aims to maximize the phenolic compounds extraction from sunflower seed cake. The following parameters were evaluated: temperature (20-70 degrees C), ethanol concentration (0-85%) and ultrasound amplitude (0-80 mu m). Response surface methodology was employed to optimize the extraction factors and a second order polynomial model provided a satisfactory fit to the experimental data. The response variables analyzed were the total phenolic compounds and the chlorogenic acid concentrations, which ranged between 751 and 1851 mg gallic acid equivalent (GAE)/100 g and 609-1635 mg CGA/100 g of sunflower seed cake in dry basis, respectively. The temperature and ethanol concentration showed the highest effect on the TPC extraction from sunflower cake. The ultrasound-assisted extraction effect was observed only in the first minute of extraction, having no influence at longer times.