Natural food and beverage colourings - Natural Food Additives, Ingredients and Flavourings - page 29

based on nor-bixin are unstable in acidic solutions and can precipitate in low pH
applications. However, the major suppliers of natural colour formulations have
overcome this issue and have acid-stable formulations available. These are
generally much weaker than the standard products and dosages must be adjusted
if such a switch is required. Brine, the high strength salt solution used in fi sh
dipping, can also cause nor-bixin formulations problems. In this case the brine
competes for the water in the nor-bixin formulation leading to precipitation. As
with the issue of acidity, the major natural colour companies have overcome the
problem in brine with a specifi c formulation. The presence of application-specifi c
formulations reinforces the benefi t of a close working relationship with a colour
supplier at the early stage of a new project involving natural colours.
Nor-bixin has the ability to bind to proteins, 6 which can make the colouring of
products such as fi sh very effective. The addition of water-soluble nor-bixin to a
brine bath prior to fi sh dipping will give an effective golden colour that is well-
fi xed and will not leach out during the supply chain or retail display. On binding
with protein, annatto will shift slightly in shade to a more red shade which can be
seen in cheeses coloured with annatto.
EU legislation restricts the use of annatto to specifi c applications and levels; 1
for example it is not permitted to colour soft drinks with annatto in Europe. The
most common applications for annatto are ice cream, fats and margarines, yellow
fi sh such as smoked kippers, breadcrumbs, yoghurts, Red Leicester cheese and
fl avoured processed cheese.
Blends of annatto with curcumin are commercially available in both water- and
oil-soluble formats. Their use is commonplace to give a classic vanilla shade in
ice cream and also in margarines, where the blend is used to replicate the shade of
β -carotene. The use of blends can also be used to create bespoke shade for specifi c
brands.
The presence of calcium ions within hard water can also lead to precipitation
of annatto formulations. This is often seen when a project moves from a laboratory
development phase where de-ionised water is common to a production scale
where local water may be used.

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2.2.4 Anthocyanins
The word 'anthocyanin' is derived from two Greek words - anthos ( fl ower) and
kyanos (blue). Over 500 different anthocyanins have been isolated from plants. 7
They are all based on a single basic core structure, the fl avyllium ion which
consists of two joined conjugated planar rings. Anthocyanins are the pigments
responsible for the red, purple, violet and blue colours seen in nature and are
localised in the plant cell vacuole.
Commercially the most important crops used for anthocyanin production are
grapes and black (or purple) carrots, but increasingly other fruit and vegetable
extracts are being used such as red cabbage and aronia. Most commercial
grapeskin extraction occurs in France and Italy. Grapeskin extraction is an aqueous
process during which sulphur dioxide is added and most of the extracted sugars