An improved method for determination of catechin and its derivatives in extract and oil of grape seeds

摘要

An improved method in place of a conventional vanillin spectroscopic method (CVSM) was developed for determination of catechin and its derivatives in extract and oil of grape seeds. For the CVSM, grape seed extracts had relatively high catechin content in the range of 17-43 percent (g/100 g of extract), while grape seed oils had relatively smaller catechin content in the range of 30-40 mg percent (mg/100 g of oil). For the improved vanillin spectroscopic method (IVSM) using a polyamide cartridge, catechin content of grape seed extracts was in the range of 4.0-7.5 percent, while that of grape seed oils was below 5 ppm. Meanwhile, the quantities of catechin and its derivatives were determined by HPLC in the grape seed extracts and oils. Four major catechins [(+)-catechin, procyanidin B2, (-)-epicatechin, and epicatechin gallate] were detected from grape seed extracts, and the ranges of concentrations were as follows: (+)-catechin, 1.35-2.60 percent; procyanidin B_2, 0.77-1.36 percent; (-)-epicatechin, 2.35-4.59 percent; (-)-epicatechin gallate, 0.06-0.30 percent. In contrast, four catechins were barely detectable in the grape seed oils. The reproducibility of four major catechins in grape seed extracts, given as coefficient of variation, was below5 percent, and the recovery close to above 95 percent. The achieved detection level of four catechins was 1-5 ppm. Additionally, the contents of catechin compositions in grape seed extract were also determined by HPLC in relation to different cultivarsand producing areas. Thus, HPLC method and IVSM using polyamide cartridge can be used as alternative to CVSM for determination of catechin and its derivatives in extract and oil of grape seeds.