Stabilisation of natural anthocyanins by micellar systems

In this paper, we discuss the influence of different micellar systems on the degradation of natural anthocyans, either glycosides and aglycones, at pH values ranging from 2.8 to 6.0. The interaction of anthocyanins, in suitable dispersed systems such as negative micelles of sodium dodecylsulphate (SDS), consistently increased their chemical stability in aqueous solutions. The results of these experiments point out how both the number of available negative charges and the presence of an organised distribution of the negative charges on the micellar surface appear to be necessary conditions to achieve the anthocyanins' stability and colour retention. The sodium dodecylbenzensulphonate (SDBS), containing an aromatic ring near the negative surface of the micelle, seems to increase the rate of decomposition. Preliminary findings of circular dicroism (CD) investigation allowed us to hypothesise that these pigments undergo an intermolecular self-association process induced by the SDS micelles and this phenomenon presumably contribute to increase stability.