Optimization of ultrasound assisted antioxidant extraction from apricot pomace using response surface methodology

Apricot (Prunus armeniaca L.), which belongs to the genus Prunus, is one of the most commonly commercialized fruits produced in Turkey. Apricot pomace, the most common byproduct of apricot nectar processing, is the press residue of the fruit flesh. Ultrasound assisted extraction (UAE) is known as one of the most efficient techniques for separation of valuable ingredients from raw materials with enhanced extraction yield. In this study, UAE parameters (temperature and time) were optimized by using Response Surface Methodology with a central composite design for maximization of the total phenolic and flavonoid contents as well as the antiradical (DPPH scavenging) activity and extraction yield. Phenolic composition and CUPRAC, ABTS and FRAP values of the extract at the highest extraction yield point was also determined. In the results, the highest phenolic and flavonoid contents, antiradical activity and extraction efficiency were determined as 1.206 mg GAE/g DM, 1.015 mg CE/g DM, 79.85% and 7.86% in apricot pomace samples at 50 °C and 90 min trial points, respectively. HPLC–DAD showed that p-coumaric acid, ferulic acid and rutin were the most abundant phenolics found in the extract. CUPRAC, ABTS and FRAP values of the extract were 30.00, 32.30 and 18.80 mg TE/100 g, respectively. In conclusion, this study provided valuable findings to food industry and other related fields for extraction of valuable bioactive compounds from apricot pomace using UAE as an eco-friendly extraction technique.