Abstract:

This paper reports the use of single-factor and orthogonal array design methods to optimize the integrated ultrasonicassisted extraction and hydrolysis of anthocyanins in black soybeans prior to their HPLC quantification. The optimal conditions for extracting and hydrolyzing anthocyanins in black soybeans were determined to be: ultrasonic-assisted extraction for 20 minutes using 2 mol/L hydrochloric acid in a mixture of half methonol and half water (V/V), followed by hydrolysis for 40 minut esat 90 ℃. The mobile phase for HPLC quantification of anthocyanins in black soybeans was a mixture of 10% formic acid aqueous solution and acetonitrile and the detection wavelength was set at 520 nm. The HPLC method exhibited a good linearity over the range from 1 to 250 μg/mL for the determination of delphinidin (Dp), cyaniding (Cy) and peonidin (Pn), with a correlation coefficient of lager than 0.9999. The contents of Dp, Cy and Pn were (31.7340 ± 1.9538), (895.3267 ± 12.9120), (26.8699 ± 0.8815) mg/100 g in black soybean seed coat, and (1.0338 ± 0.0160), (76.6534 ± 0.2322), (2.1283 ± 0.3244) mg/100 g in whole black soybean, respectively.

Key words: anthocyanins, hydrolysis, optimization, HPLC quantification, database, black soybean