Abstract: The objective of this study was to optimize the extraction of sterols from lotus seed plumule with acetone as the extraction solvent using one-factor-at-a-time method and response surface methodology. The independent variables were extraction time, temperature, solid-to-solvent ratio and number of extractions, while the response variable was the yield of total sterols. This study also determined the sterol composition of lotus seed plumule by gas chromatography-mass spectrometry (GC-MS). The highest yield of total sterol (1.67 ± 0.11)% was achieved under optimal conditions: extraction time, 12 min; temperature, 44 ℃; solid-to-solvent ratio, 1:12 (g/mL); and three extraction cycles. The extract was composed of esterified and free sterols, accounting for 84.97% and 11.95%, respectively. Besides, seven sterols were identified, among which, sitosterol (58.27%), Δ5-avenastero (22.99%) and campesterol (12.64%) were predominant. Additionally, both glyceride and sterol ester had high level of unsaturated fatty acids (77%), especially linoleic acid. Sterol ester contained higher levels of long chain fatty acids, such as behenic acid and lignoceric acid than glyceride.

Key words: lotus seed plumule, acetone, extraction, yield of total sterol, gas chromatography-mass spectrometry (GC-MS)