Cosmos bipinnatus Cav., an alternative to synthetic dyes? study of its stability against degrading factors

The pigments of Cosmos bipinnatus were characterized for their possible application as natural dyes. In the extraction of the pigments, three solvents were evaluated, being the combination of water and ethanol the one that presented the best results. Subsequently, the stability of the pigments was evaluated under different conditions of pH, temperature and light radiation during 41 days of storage. Analysis of the degradation kinetics of anthocyanins indicated a first order reaction and a half-life of 0.7 to 63 days. At the end of storage, polymeric color formation increased by pH effect (1.6 - 96.2%) while anthocyanin concentration decreased by temperature effect (1.1 to 0 mg cyn-3-glu g-1). Antioxidant activity was affected by storage conditions, decreasing from 251 mg ET g-1 to 69 mg ET g-1. Regarding color, it was preserved longer at pH 4, unlike the samples at pH 10 and 7. According to the results, it is suggested to use the extract of Cosmos bipinnatus flowers at pH 4, in foods whose processing and storage is carried out at refrigeration temperature.