Efficient and selective method to separate triterpene acids by direct treatment of apple peels with alkaline ethanol

Triterpene acid extraction from dried apple peels of Fuji and Gala varieties in 2%NaOH/ethanol at room temperature, followed by filtration and acidification (pH 3), was investigated, comparing to a classical exhaustive extraction (Soxhlet, 2 h, with ethanol and methanol, >97% recovery). Alkali-ethanol process yielded 4.35-6.86% (w/w) of whitish extracts, up to 15 times less than Soxhlet but with same recovery (P > 0.05) of ursolic and oleanolic acids. Alkaline extraction of previously defatted peels led to same recovery (P > 0.05), but the yield increased slightly (P < 0.01). The cost-effective and environmental-friendly procedure prepares triterpene-rich extracts from apple peels at high recovery, directly eliminating the cutin and avoiding prior treatments with hazardous organic solvents.