Hibiscus sabdariffa L. calyces as a source of anthocyanins rich extracts to be used as a natural food colouring agente
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Colour is the most important sensory perception when it comes to setting peoples
expectations regarding the likely taste and flavour of food [l]. Since the consumers
are more aware regarding the additives that are incorporated into food products, they
have shown a preference for the consumption of natural additives over the artificial
ones. This hás been one ofthe research lines ofthe scientific community, searching for
natural additives to replace the artificial counterparts [2].
The present work studies the stability of an extract obtained from hibiscus calyces
(Hibiscus sabdariffa L.), to test its possible use as a natural colourant in foods. The
aqueous stability of the extract was monitored using the total anthocyanins content
(TAC) as response (determined by HPLC-DAD) in function of time (t, 14 days),
temperature (T, 4 to 70 °C), and pH (2 to 6). Aided by mechanistic/phenomenological
models, the conditions favouring the stabilization ofthe extract were provided.
The results obtained showed that the aqueous stability of the H. sabdariffa extracts
was higher at lower pH values, shorter t values and T between 4 to 35 °C. However,
certain new stable combinations of conditions were found, providing a wide range of
conditions, in which the TAC ofH. sabdariffa extracts will remain stable at values of T
within the range of50 to 70°C. Such facts, will help to understand how to incorporate
stable natural extracts, rich in TAC, as natural colorant additives in food products, that
may require strong processing conditions, such as bakery and dairy products.
These results provide useful information for: i) potential industrial use offí. sabdariffa
extract as alternative sources of natural additives rich in TAC; and ii) shelf-life
calculations and TAC loss predictions at specific conditions of T and pH. Finally,
the results obtained showed a certain agreement with previous reports regarding the
stability of anthocyanin compounds, but providing a new alternative source.
