2.5 Determination of total anthocyanin content
Determination of the total amount of anthocyanins (TAC) was adapted from reported spectrophotometric method (Sompong et al., 2011). Anthocyanins were extracted with acidified methanol (methanol and 1 M HCl, 85:15, v/v) with a solvent to sample ratio of 1:10. Absorbance was measured after centrifugation (at 3,000 g for 15 min) at 525 nm against a reagent blank. Cyanidin-3-glucoside-chloride (Sigma-Aldrich, St. Louis, MO, USA) was used as standard pigment, and TAC was expressed as mg cyanidin 3-glucoside equivalent per 100 mL extract.