Optimization of ultrasonic-assisted extraction of antioxidant tannin from young astringent persimmon (Diospyros kaki L.) using response surface methodology

摘要

Ultrasonic-assisted extraction (UAE) was applied for tannin extraction from young persimmon (Diospyros kaki L.) and extraction conditions were optimized using response surface methodology to compare with traditional water bath extraction (WBE). The maximum yield (33.96 mg/g) extracted by UAE was obtained under conditions of ultrasonic power 207 W, time 30.9 min, L:S ratio 21.1:1 (mL:g) and 55.0 8C, whereas tannin yield reached 32.39 mg/g under parameters of 73.5 8C, time 63.0 min, and L:S ratio 32.4:1 (mL:g) when using WBE. Comparatively, higher tannin was extracted under optimal UAE condition than WBE method, mainly associated with its great damage on original structure of persimmon pulp and peel based on morphological analysis. While there was no significant difference for UV and FT-IR spectra among tannin extracted by different methods. Moreover, tannin possessed excellent DPPH radical scavenging and ferric reducing activities in a dosage-dependent manner, showing potential application in medicinal and food industry.