The scalability of the extraction and purification process was
demonstrated by producing purified anthocyanins from 19 kg
of completely pigmented purple-fleshed potatoes in a single
batch. Freeze-drying was used as the pretreatment method.
The extraction of anthocyanins was carried out using aqueous
20 vol.% acidic (7 vol.% acetic acid) ethanol solution with
solid:liquid ratio of 1:5. Coarse solids were separated from
the resulting extract by filtration under vacuum, and the
fine solids by centrifugation (2600 rpm, 15min, ALC 4237,
ALC International). The coarse particles from the first extraction
were contacted again with the extraction medium with
solid:liquid ratio of 1:3 in order to maximize the anthocyanin
yield. Removal of ethanol from the solid-free extract was done
by evaporation (p = 1 atm, T = 60 ◦C).