Anthocyanin content was determined under two
treatments. Samples packaged in air or packaged
under vacuum. Anthocyanins were extracted by two
types of extraction: (1) with 250 ml of distilled water,
(2) with 2000 ppm sodium metabisul®te (calculated as
SO2). Samples were heated in a water bath at 608C for
15 min and ®ltered. The volume of water phase was
measured. An aliquot of extract was acidi®ed to pH 1.0
and anthocyanins were determined using the pH dierential
method (Fuleki and Francis, 1968). Optical density
was read at 520 nm (UV-visible varian DHS 200)