The residue was diluted in 5 mL ultrapure water and passed
through a 0.2 mm membrane filter (Millipore, MSI, Westborough,
MA), and 20 mL was analyzed by HPLC. For each sample, two
independent extracts were prepared, purified and analysis
separately. Anthocyanins were identified by performing the
absorption spectrum of pure standards, and selecting the
wavelengths at which these compounds standard showed the
absorption maxima. It was found that Pgd-3-glu showed a
maximum absorption at 495 nm and Cyn-3-glu to 513 nm