COLORANT HYDROSOLUBLE POUR PRODUITS COMESTIBLES

WATER-SOLUBLE COLORANT FOR FOOD PRODUCTS

Abrégé anglais

ABSTRACT
WATER-SOLUBLE COLORANT
FOR FOOD PRODUCTS
A water-insoluble dye, such as indigo, is com-
bined in its soluble leuco form, in aqueous solu-
tion, with a water-soluble food grade substrate such
as starch. After oxidizing to convert the dye to
its water-insoluble, colored, form, the aqueous solu-
tion is dried to provide a dry, water-soluble food
colorant comprising the substrate dyed with the
water-insoluble dye. The product is conveniently
provided in particulate form such as by spray dry-
ing, and finds particular use in dry beverage mixes
where a water-soluble colorant is desired.

Revendications

WE CLAIM:
1. A method for making dry water-soluble food
colorant comprising a water-soluble food grade substrate dyed
with a water-insoluble dye,
comprising the steps of
providing an aqueous solution containing a normally
solid water-soluble food grade substrate and containing a leuco
form of an edible water-insoluble dye which is water-soluble
in its leuco form, with the dye being present in amounts of
from about 0.1 to about 25% based on the weight of the sub-
strate,
oxidizing the leuco form of the dye in the aqueous
solution to change the dye to its colored, water-insoluble
form; and
drying the aqueous solution to provide the dry,
water-soluble food colorant.
2. A method according to claim 1, wherein the dye
is indigo.
3. A method according to claim 1, wherein the food
grade substrate comprises starch, hydroxy propyl cellulose
carboxymethyl cellulose, and food grade cellulose derivatives.
4. A method according to claim 1, wherein the
aqueous solution is spray dried whereby the colorant is pro-
duced in particulate form.
5. A method according to claim 1, including the
further steps of heating the aqueous solution containing the
dye in its colored, water-insoluble form to insolubilize the
water-soluble substrate, dissolving the insolubilized substrate
in water, and drying the resultant aqueous solution.
6. A method according to claim 1, wherein the sub-
strate is in particulate form.
7. A dry water-soluble food colorant comprising
a water-soluble food grade substrate dyed with a water-
insoluble dye and wherein the dye is present in amounts of from

about 0.1 to about 25% based on the weight of the substrate
when prepared according to the process of claim 1 or its
obvious chemical equivalent.
8. A dry water-soluble food colorant according to
claim 7, wherein the dye is indigo when prepared according to
the process of claim 2.
9. A dry water-soluble food colorant according to
claim 7 wherein the food grade substrate comprises starch,
hydroxy propyl cellulose, carboxymethyl cellulose, and food
grade cellulose derivatives when prepared according to the
process of claim 3.
10. A dry water-soluble food colorant according to
claim 7 in particulate form when prepared according to the
process of claim 4.
11. A dry water-soluble food colorant according to
claim 7 having an average particle size of from about 1 to
about 1000 microns when prepared according to the process of
claim 4.
12. A dry water-soluble food colorant according to
claim 7, when prepared according to the process of claim 5 or
its obvious chemical equivalent.
13. A dry water-soluble food colorant according to
claim 7 when prepared according to the process of claim 6.
14. A method for making dry water-soluble food
colorant comprising a food grade starch substrate dyed with
water-insoluble indigo dye,
comprising the steps of
providing an aqueous solution containing the starch
substrate and containing a leuco form of the indigo dye which
is water- soluble in its leuco form, with the dye being pre-
sent in amounts of from about 0.1 to about 25% based on the
weight of the substrate,

oxidizing the leuco form of the dye in the aqueous
solution to change the dye to its colored, water-insoluble
form, and
drying the aqueous solution to provide the food
colorant.
15. A method according to claim 14 wherein the sub-
strate is in particulate form.
16. A method according to claim 14, wherein the
aqueous solution is spray dried to provide the colorant in par-
ticulate form.
17. A dry water-soluble food colorant comprising
a starch substrate dyed with from about 0.1 to about 25% based
on the weight of the substrate of water-insoluble indigo dye
when prepared according to the process of claim 14 or its
obvious chemical equivalent.
18. A food colorant according to claim 17 in parti-
culate form when prepared according to the process of claim
16.
19. A food colorant comprising a particulate starch
substrate having an average particle size of from about 1 to
about 1000 microns dyed with from about 0.1 to about 25% based
on the weight of the substrate of water-insoluble indigo dye,
when prepared according to the process of claim 16.

Description

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CASE 2921
DESCRIPTION
WATER-SOLUBLE COLORANT
FOR FOOD PRODUCTS
05
Technical Field
This invention relates to a water-soluble food
colorant, to food products containing same, and to a
method of making the colorant.
At the present time, there are a limited number
of dyes which are approved for food use. While the
approved dyes are widely used, there is a continuing
need for alternative dyes, at least for back-up use
should need arise. For example, two blue dyes are
presently approved for food use in the United States:
FD and C Blue No. 1 and FD and C Blue No. 2. ~hile
a limited number of back-up dyes have been develop-
ed, at least most have one or more major drawbacks
of cost, functionality, availability, or legality.
Back-up blue dyes which have been developed are ex-
tremely limited in number and suffer from one or more
of the disadvantages mentioned above.
It is an object of the present invention to provide
water-soluble food colorants which are free of the
foregoing disadvantages. It is a further object to
provide food products colored with these food colorants
and i-t is a further object to provide a dependable
and simple method of making the food colorants.
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Backgroiund Art
The foregoing and other objects which will be
apparent to -those of ordinary skill in the art are
achieved in accordance wi-th -the present invention
05 which provides a water-soluble food colorant com-
prising a water-soluble food grade substrate dyed
with a water-insoluble edible dye, which provides
food products colored with that food colorant, and
which ~rovides a method of making that colorant
which method comprises providing an aqueous so].ution
containing a wa-ter-soluble food grade substrate and
containing a leuco form of an edible water-insoluble
dye which is water-soluble in its leuco form, oxi-
dizing the leuco form of the dye in said aqueous sol-
ution to change the dye to its colored, water-
insoluble form, and drying the aqueous solution to
provide a dry, water-soluble food colorant compris-
ing said water-soluble food grade substrate dyed
with said water-insoluble dye.
Disclosure of the Invention
In practicing the invention, an edible, water-
insoluble dye is combined with a water-soluble food
grade substrate to color the substrate. The colored
substrate is water-soluble and provides the water-
soluble colorant provided by the invention.
The substrate can be any normally solid water-
soluble food grade substrate such as starch, food-
grade cellulose deriva-tives such as hydroxy propyl
cellulose, carboxymethyl cellulose, and other water
soluble polymers, and the like. The choice of sub-
strate is quite wide and the food literature is re-
plete with many examples. The substrate must be cap-
able of being dried from aqueous solution to provide
35 ` a dry product and is preferably such that the dried

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product can be provided in part:iculate form and pre-
ferably free-flowing. Most preferably, the sub-
strate is one such as starch, which can be spray
dried from aqueous solution -to form free flowing par-
05 ticles. The particle size of the particulate pro-
duct can vary widely but is preferably chosen to pro-
vide rapid dissolution in water such as is desired
in a dry beverage mix. An average par-ticle size of
from l -to ~000 microns is usually suitable.
The dye is one which is edible, which has col-
ored and leuco forms, and which is water-insoluble
in its colored form and water~soluble in its leuco
form. Moreover, the dye is one which will dye the
selected substrate. Conversely, of course, the sub-
strate is dyeable by the chosen dye. This require-
ment is readily me-t because there are many clases of
water-soluble food grade substrates which are read-
ily dyeable. In addition, the dye is one which is
readily changed from lueco form, when in aqueous sol-
ution, to its colored form. Preferably, the dye isone which is changed to colored form by simply bubbl-
ing air or oxygen through an aqueous solution of the
leuco form of the dye. A typical and preferred dye
is indigo, a water-insoluble textile dye derived or-
iginally from the indigo plant. FD and C Blue No.2, one of the two presently approved dyes mentioned
above, is the sulfonic acid disodium salt of indigo
and is water soluble. Indigo is one of a class of
dyes known as vat dyes which are water-insoluble in
their colored form and are water-soluble only in
their reduced leuco forms. These vat dyes form a
class of dye which is readily useful in the present
invention, su~ject of course, to the restrictions
mentioned above.

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The amount of dye in the colorant product can
vary widely. In general, the dye will be present in
an amount of 0.1 to 25% by weigh-t based on -the weight
of the substrate.
05 The product is readily made by dissolving the -
water-soluble, leuco form, of the dye and the norm-
ally solid water-soluble food grade substrate, in
aqueous solution. The dye is then oxidized into its
oxidized, colored, water-insoluble state while in
the aqueous solution in intimate admix-ture with the
dissolved food grade substrate. Oxidation is pre-
ferably accomplished by simply bubbling air or oxy-
gen into the aqueous solution. The aqueous solution
is then dried in any convenient manner, preferably
after fil-tering to remove any undissolved solids, to
provide a dry colorant comprising the ~ater-soluble
substrate dyed with the colored form of the dye. In
an alternative process, after oxidizing, the aqueous
solution is treated to effect precipitation or in-
solubilizing of the substrate. For example, certaincellulosic substra-tes may be insolubilized by heat-
ing. The precipitate is then redissolved in water
and this water solu-tion is then dried to provide a
colored product. The product is preferably particu-
late and drying of the aqueous solution is thus pre-
ferably achieved by spray drying which provides a
particulate dried product.
Best Mode _or Carrying Out the Inventlon
The product can be used as a colorant in place
of other water-soluble colorants for food products.
The product finds particular utility as a water-
soluble colorant for a dry beverage mix.

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EXAMPLE 1
The ~50 ml of distilled water are added to 0.625
grams of NaOH followed by 0.9 grams of indigo with
constant stirring. Gentle heating is commenced fol-
05 lowed by the slow addition of sodium dithionite(Na2S2O4) and heating is continued until the solu-
tion becomes clear with a yellowish/green cast.
Twenty-~ive grams of starch (Frodex 10) are added
slowly to prevent clumping. Air is then bubbled in-
to the solution for a few minutes until the solutionbecame no darker blue. The solution is then filter-
*
ed through a Whatman #41 (fast) filter paper to re-
move undissolved solids and spray dried under the
following conditions:
inlet temperature 150C
outlet temperature 90C
air flow 555 ml/min
The resulting powder will be light blue and quite
water-soluble.
EXAMPLE 2
A solution of indigo in reduced form is pre-
pared as in Example 1. * Fifteen grams of hydroxy-
propyl cellulose (Klucel HF) is dissolved in 300 ml
cold water and the solution is added to the indi~o
solution with constant stirring. The solution is
permitted to cool and air is bubbled in as in
Example 1, to oxidize the indigo to its blue color.
The solution is then heated to insolubilize the hy-
droxypropyl cellulose and is filtered hot, using afine screen. The gel is re-dissolved in 500 ml cold
water and is freeze dried until dry. The product is
a water soluble blue powder.
* Trade Mark
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E AMPLE 3
A dry beverage mix is prepared from -the follow-
ing ingredients:
Sucrose 15g
05 Colorant of Example 2 0.18g
FD & C Yellow #S 0.06g
Citric Acid 0.50g
Lemon Lime Flavor 0.05g
When added to lS0 ml water, the mix readily dis-
solves to yield a lemon-lime beverage mix having a
greenish color similar to that achieved with similar
mixes using a conventional blue colorant.