Extraction of betacyanins from Gomphrena globosa L. flowers: Choosing na acid as adjuvant
Artigo de Conferência
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resumo
Betalains are plant derived natural pigments that are presently gaining popularity for use as natural
colorants in food industry. Although being betalains from red beetroot already used as food colorant (E-
162), these compounds are not as well studied as compared to other natural pigments such as
anthocyanins, carotenoids or chlorophylls (I]. Since food additives are on the focus of public interest, it is
becoming increasingly important to meet consumers' expectations for natural and healthy products.
Hence, the search for new plant-derived colorants for the food industry is still necessary [2]. Betalains
were originally called 'nitrogenous anthocyanins', which incorrectly implied structural similarities
between the two pigment classes. There are two structurally different types of betalains: the yellow/orange
betaxanthins which are the condensation products of betalamic acid and assorted amino compounds, and
the red betacyanins which are formed by glycosylation and acylation of cyclo-DOPA [3]. Looking at the
chemical structure of the pigment, the addition of an acid to the extraction solvent will increase the
affinity of the pigment with the solvent. The aim of this study was to use Gomphrena globosa L. flowers,
as an alternative plant source to obtain these pigments and to evaluate the best acid to be used within the
extraction procedure. For that purpose three different acids (acetic, hydrochloric and phosphoric acids, all
ofthem allowed by the food industry), adjusted at the same pH, were tested during a maceration extraction
procedure. After the extraction a purification through C18 column was performed in order to obtain a more
concentrate extract in betacyanins. The results were analysed by HPLC-PDA-MSIESI. The betacyanin
profile allowed the identification of gomphrenin IIJIII and isogomphrenin IIIIII and the best results were
achieved by performing the extraction procedure using hydrochloric acid (6.6 mg/g extract), while
phosphoric acid only presented trace amounts of these compounds. When acetic acid was used, the
pigment extracted was 6.8 times less (0.97 mg/g extract) when compared to HCI. In conclusion
hydrochloric acid can be considered the most suitable acid to be applied in the extraction procedure of
these pigments.
