Development of a natural colouring agent based on betacyanins from plant origin
Artigo de Conferência
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resumo
A current worldwide trend of research is the search for alternative natural sources of
colorants to avoid the unsafe effects caused by the synthetic counterparts.
Betacyanins, which are betalain pigments displaying a red‐violet colour, have been
reported to be three fold stronger than the yellow‐orange dye produced by
anthocyanins. Although being less commonly used than anthocyanins and carotenoids,
betacyanin applications cover a wide range of matrices, where they are mainly used as
additives or supplements in the food, cosmetics, pharmaceuticals and livestock feed
industries. Betacyanins are obtained mainly from the red beet, Beta vulgaris L.
(between 10 to 20 mg per 100 g of fresh pulp), but alternative primary sources are
needed. The floral parts of Gomphrena globosa L. represent a potential source of
betacyanins. In this context, the present study aims to evaluate: 1) a process for the
selection and separation of pigmented floral bracts and bracteoles (~4 % of the dried
plant material); 2) the identification of the major betacyanin compounds (gomphrenin
II and III, and isogomphrenin II and III); 3) the most appropriate extraction procedures
(from maceration, microwave and ultrasound assisted techniques) together with the
optimal conditions that maximize betacyanin extraction (time, temperature, solidliquid
ratio and ethanol‐water ratio); and 4) shelf life and colour stability of the
obtained natural agent. The responses were assessed by the quantification of
betacyanins by high‐performance liquid chromatography coupled with a photodiode
array detector and mass spectrometry with electron spray ionization. In addition,
results clarified some contradictory trends described in the literature concerning the
time and temperature variables, finding a considerable improvement on the
betacyanins yield (higher than that typically found for Beta vulgaris), without
displaying any type of degradation patterns.
