Another kind of cane flavonoids is the anthocianins. These compounds are responsible for the red, blue and purple colours in plants. In sugar cane the red colour that can appear in cane surface is due to these compounds. As anthocianins are coloured at acid conditions and colourless at high pH they have an IV inferior to the unity. These compounds are unstable at neutral or alkaline conditions and are decomposed by heat (Paton, 1992). Heating the anthocianins at pH 7 they are partially decomposed, with loss of a ring, originating colourless compounds (Smith and Paton, 1985).
The action of sulphites provokes antocianins decolourization being the colour regenerated through acidification (Smith and Paton,1985).
Anthocianins are located at higher concentrations at the cane groing parts. These compounds polimerize rapidly and the juices are more unstable due to their presence (T009 - 1415).
Paton N.H., 1992, The origin of colour in raw sugar, Proc. of Aust.S.S.C.T. Conf., 8-17
Smith P., N.H. Paton, 1985, Sugar cane flavonoids, Sugar Tech. Rev., 12, 117-142