Total anthocyanin concentration (TAC) was quantified using the
pH differential method with two buffer systems comprising of
potassium chloride (pH 1, 0.025 mol L1) and sodium acetate (pH
4.5, 0.4 mol L1).The juice sample (1 mL) was mixed with 9 mL
of pH 1 and pH 4.5 buffers, separately. The absorbance of the
mixtures was measured at 520 and 700 nm using a UV–vis
spectrophotometer (Thermo Fisher Scientific, Madison, MI, USA),
after 10 min incubation of the mixture in a dark cabinet.