Flowers of Gomphrena globosa L. as an alternatve source of betacyanins: Optimization of the extraction using response surface methodology
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resumo
Betacyanins are betalain pigments that display a red-violet colour which have been reported to be three
times stronger than the red-violet dye produced by anthocyanins [1]. The applications of betacyanins
cover a wide range of matrices, mainly as additives or ingredients in the food industry, cosmetics,
pharmaceuticals and livestock feed. Although, being less commonly used than anthocyanins and
carotenoids, betacyanins are stable between pH 3 to 7 and suitable for colouring in low acid matrices. In
addition, betacyanins have been reported to display interesting medicinal character as powerful
antioxidant and chemopreventive compounds either in vitro or in vivo models [2]. Betacyanins are
obtained mainly from the red beet of Beta vulgaris plant (between I 0 to 20 mg per I 00 g pulp) but
alternative primary sources are needed [3]. In addition, independently of the source used, the effect of the
variables that affect the extraction of betacyanins have not been properly described and quantified.
Therefore, the aim of this study was to identifY and optimize the conditions that maximize betacyanins
extraction using the tepals of Gomphrena globosa L. flowers as an alternative source. Assisted by the
statistical technique of response surface methodology, an experimental design was developed for testing
the significant explanatory variables of the extraction (time, temperature, solid-liquid ratio and ethanolwater
ratio). The identification was performed using high-performance liquid chromatography coupled
with a photodiode array detector and mass spectrometry with electron spray ionization (HPLC-PDAMS/
ESI) and the response was measured by the quantification of these compounds using HPLC-PDA.
Afterwards, a response surface analysis was performed to evaluate the results. The major betacyanin
compounds identified were gomphrenin 11 and Ill and isogomphrenin IJ and Ill. The highest total
betacyanins content was obtained by using the following conditions: 45 min of extraction. time, 35•c, 35
g/L of solid-liquid ratio and 25% of ethanol. These values would not be found without optimizing the
conditions of the betacyanins extraction, which moreover showed contrary trends to what it has been
described in the scientific bibliography. More specifically, concerning the time and temperature variables,
an increase of both values (from the common ones used in the bibliography) showed a considerable
improvement on the betacyanins extraction yield without displaying any type of degradation patterns.
