No abstract

This paper described a modified HPLC method for the determination of eight acylated anthocyanins in purplefleshed sweet potato tuber samples, including lyophilized powder and concentrated juice. Recoveries determined for two materials spiked with anthocyanin levels of 71 μg g _ 1 to 8.8 mg g _ 1 ranges 91.8-105.0%. For repeatability, the relative standard deviation and intermediate precision ranged from 0.8% to 5.0% and 1.9% to 8.2%, respectively. HorRat values ranged from 0.3 to 1.0, except for YGM-1a and YGM-1b in two samples, which were well within the limits of performance acceptability. The proposed method showed good intralaboratory reproducibility in the range from 0.10 ± 0.0027 (mean ± expanded measurement uncertainty, k = 2) to 0.

A method based on the 4-dimethylaminocinnamaldehyde (DMAC) method was optimized for determination of total proanthocyanidin content in grain legumes using 96-well microplates. The recovery determined for a milled soybean material spiked with black soybean seed coat extract equivalent to 1.0, 2.0 and 4.2 mg/g of proanthocyanidin ranged from 96. 1 to 97. 9 %. Duplicate determinations of total proanthocyanidin content in eight different grain legumes were performed on three different days. Statistical treatment revealed that the relative standard deviation of the repeatability (RSD r) and the relative standard deviation of the intermediate reproducibility (RSD int) for determination of total proanthocyanidin content was 0.5 to 4.1 % and 0.9 to 4.7 %, respectively. The HorRat values (RSD int /predicted RSD R) ranged from 0.17 to 0.87. This demonstrates that the proposed method for determining total proanthocyanidin content in grain legumes had good intralaboratory reproducibility. The contents of proanthocyanidin, ranging from 0.33 to 2.97 mg/g, in 59 samples of black soybean determined by the DMAC method were strongly correlated to those determined by the vanillin-sulfuric acid method (r=0.980). However, the contents in black soybeans determined by the vanillin-sulfuric acid method were higher when compared with the DMAC method in almost all samples, when the content obtained by the DMAC method was directly compared to that obtained by the vanillin-sulfuric acid method.

Determination of Total Anthocyanin and ProanthocyanidinContents in Black Soybeans (Glycine max (L.) Merr.