Optimizing conditions for anthocyanins extraction from purple sweet potato using response surface methodology (RSM)

Optimization for purple sweet potato (Ipomoea batatas (L.) Lam) anthocyanins (PSPAs) extraction was investigated using response surface methodology in this paper. PSPAs were extracted using acid–ethanol at different extraction temperature (40–80 °C), time (60–120 min) and solid–liquid ratio (1:15–1:30). The combined effects of extraction conditions on PSPAs yield and color attributes (expressed as L*, C* and H) were studied using a three-level three-factor Box–Behnken design. The results showed that The highest yield (158 mg/100 g dw) of PSPAs were reached at the temperature 80 °C, extraction time 60 min, and solid–liquid ratio 1:32. PSPAs yield indicated a high and significant correlation with L* (P<0.05; r=−0.961) and it was significantly affected by extraction temperature (P<0.01) and solid–liquid ratio (P<0.05).