Improving the stability of the black carrot (Daucus carota L.) colourant
View/ Open
Iliopoulou2016.pdf (191.6Mb)
Date
28/06/2016Item status
Restricted AccessEmbargo end date
31/12/2100Author
Iliopoulou, Ioanna
Metadata
Abstract
The replacement of artificial with natural dyes is one of the most challenging
research fields in the food production area. Recent studies have shown that some
frequently used synthetic colours, called the “Southampton 6 Colours” may be linked
with hyperactivity in children. The purpose of this work is to analyse the degradation
behaviour of black carrot, a natural, red dye commonly used for colouring food
products, and subsequently improve its stability during heat and storage conditions.
The stability of the black carrot mixture to heat exposure was investigated at a range
of pH values by heat-treating aqueous solutions in a domestic oven at around 180oC
to maintain the temperature at 100oC and the powdered material in a furnace at
180oC (typical baking conditions). 1H NMR (800 MHz) spectroscopy was used for
the assignment of the aromatic chemical shifts of the black carrot mixture by
overlaying them with the characterised 1H NMR chemical shifts of the individual
components separated by RP-HPLC. Integration of high-resolution 1H NMR (800
MHz) spectra was used to follow the relative degradation of each of the components.
Different procedures for the complexation of black carrot with metal oxides were
developed, for which colourants of different colour shades were prepared.
Spectroscopic techniques were used to follow the degradation of the complexes
which were heat-treated at 180oC. Nano-scale investigation of the metal oxide
powders was also carried out. The optimised colourants were tested on a bench scale
and subsequently on an industrial scale in food pilot procedures.
The successful complexes produced were found to be more heat stable compared to
the commercial black carrot dye. The developed technologies are cheap and easy-to-produce
methods to create intense heat and storage stable coloured pigments which
can be used for the replacement of existing artificial dyes during food processing.