METHOD FOR EXTRACTING XANTHOPHYLLS FROM CORN

METHODE D'EXTRACTION DE PIGMENTS XANTHOPHYLLES DU MAIS

English Abstract

The method of the invention uses raw corn, or a corn by-product as a source.
The source is mixed with an alcohol (2) to produce an alcohol-corn slurry.
Centrifugation or filtration (3) produces a clear filtrate from the alcohol-
corn slurry. A membrane filtration (4a) step is then used to separate purified
xanthophylls. Other steps may be combined with the basic process to produce
additional corn products, such as oil and zein.

French Abstract

L'invention concerne une méthode utilisant du maïs ou un produit dérivé du maïs comme source. Cette source est mélangée avec un alcool (2) pour produire une suspension épaisse à base d'alcool et de maïs. Après centrifugation et filtration (3) de la suspension épaisse, on obtient un filtrat clair. On procède ensuite à une filtration sur membrane (4a) pour séparer les pigments xanthophylles purifiés. D'autres étapes peuvent être combinées avec le procédé de base pour produire des produits supplémentaires à base de maïs, telle que de l'huile et de la zéine.

Claims

1. A method for extracting xanthophyll from corn, the method
comprising steps of:
mixing a source of corn with alcohol to produce an alcohol-corn slurry;
separating solids from the alcohol-corn slurry to produce a clear filtrate;
membrane filtering the clear filtrate to separate xanthophyll concentrate
from the clear filtrate.
2. The method according to claim 1, wherein said step of separating
comprises centrifugation.
3. The method according to claim 1, wherein said step of separating
comprises filtration.
4. The method according to claim 1, wherein said source of corn
comprises raw corn.
5. The method according to claim 1, wherein said source of corn
comprises a corn processing derived co-product.
6. The method according to claim 1, further comprising a step of
drying the source of corn prior to said step of separating.
7. The method according to claim 1, wherein said step of mixing
mixes alcohol having a concentration of above approximately 92% with said
source of
corn.
8. The method according to claim 1, further comprising a step of
solvent extraction, prior to said step of mixing, to remove oils from the
source of corn
and a step of desolventization to remove excess hexane prior to said step of
mixing.
6

9. The method according to claim 1, further comprising a step of zein
filtration, prior to said step of membrane filtrating to remove zein from the
clear filtrate
and obtain a zein concentrate.
10. The method according to claim 9, wherein said step of zein
filtration comprises ultrafiltration.

Description

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METHOD FOR EXTRACTING '~ANTHOPHYLLS FROM CORN
The invention generally concerns extraction of xanthophylls. The
invention more specifically concerns a method for extraction xanthophylls from
various forms of corn, including raw corn as well as corn processing derived
co-
products.
BACIfGROUND ART
Xanthophylls are oxygenated cartenoid compounds that are useful as
yellow pigments that can be used in animal feeds and human food. Various
plants
and some animal products, e.g. egg yolks, are a source of xanthophylls. Corn
gluten is often fed to chickens to impart a yellow color to the chickens which
is
preferred by consumers of chicken, especially those in the US market. Major
producers of chicken have even been known to advertise the yellow hue of their
chicken. The method of feeding corn gluten serves this purpose. It is
preferable,
though, to use extracted xanthophylls to produce consistent results.
Prior art methods have extracted xanthophylls from marigolds. One
such method is described in U.S. Patent No. 5,382,714 to Khachik. The specific
xanthophyll, lutein, is extracted from saponified marigold oleoresin.
Extracted lutein is used currently in the health food market, and
typically sold as a gel capsule. Some studies have linked lutein, and another
xanthophyll, zeaxanthin, to prevention of age-related macular degeneration
(AMD), a disorder that can cause blindness in humans. According to a 199 study
by Seddon et al. at Harvard University, the human body absorbs lutein and
zeaxanthin from food directly into the human plasma and deposit in the macular
?5 and retina of the eyes. The body even metabolically transforms lutein into

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zeaxanthothin to be deposited in the macular region. The lutein extracted from
marigolds has not, however, been approved by the FDA as a food additive.
Marigolds, unlike corn, are not on the Generally Recogni2ed As Safe (GRAS)
list
of the FDA. There have therefore been efforts to produce xanthophylls from
products that are on the GRAS list.
U.S. Patent No. 5,602,286 to Muralidhara describes a method for
producing xanthophylls from corn gluten meal. Corn gluten meal is a product of
corn wet milling. The process requires a saponification reaction. Its
application is
limited because of its requirement for wet milling as a precursor to produce
the
corn gluten required for the process.
Thus, there is a need for an improved method for producing
xanthophylls from corn. That need is met or exceeded by the method of the
present invention, which permits extraction of xanthophylls from raw corn as
well
as corn co-products such as corn gluten meal.
DISCLOSURE OF INVENTION
The method of the invention uses raw corn, or a corn by-product as a
source. The source is mixed with an alcohol to produce an alcohol-corn slurry.
Centrifugation or filtration produces a clear filtrate from the alcohol-corn
slurry.
A membrane filtration step is then used to separate purified xanthophylls.
BRIEF DESCRIPTION OF THE DRAWING
Other objects, features and advantages of the invention will be
apparent by reference to the drawing figure. The figure is a block diagram
illustrating the method of the invention.
BEST MODE OF CARR~'ING OUT THE INVENTION
Referring now to the figure, the method of the invention is capable
of using raw corn of any form, or corn processing products, such as corn
gluten

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meal produced in wet milling processes. A preliminary dry grind step 1 is
required
if the corn source is raw corn. In the case of corn processing products, or
raw corn
which, after grinding, is excessively moist a drying step 1 a should be
conducted to
facilitate a reaction extraction step 2.
The extraction step 2 is conducted with an alcohol of concentration
ranging from about 40°~o to 100%. The preferred alcohol diluent is
water. 'The
reaction in the extraction step 2 becomes efficient above approximately 70%
alcohol, and alcohol concentrations at or above approximately J2% are
preferred if
an oil based xanthophyll is preferred. The particular range of alcohol chosen
may
depend upon whether other products such as corn oil or zero are desired to be
obtained. Oil extraction is efficient with alcohol of about 90-100%
concentration,
while zero is optimally obtained at about (i0-90% concentration.
Either batch extraction or continuous extraction is suitable. The
continuous extraction can be in a column or commercial co-current or
countercurrent extractor such as those manufactured by Crown or Lurgi-PSI for
use in the vegetable oil industry. The preferred type of alcohol is ethanol
However, other alcohols, e.g., isopropanol, can be used in the extraction
step.
Temperatures between about 5°C and 75°C are suitable, and
the extraction
reaction should be allowed sufficient time to complete, typically 15 to 120
minutes. The result of the extraction step 2 is a alcohol-corn slurry.
The alcohol-corn slurry is then subjected to filtration or
centrifugation (step 3) to remove corn solids. This step may not be required
depending upon whether the method of extraction used in step 2 also removes
solids. Typical commercial extractors remove solids such that the filtration
or
centrifugation step 3 would not be required. The objective of filtration or
centrifugation is to remove large or suspended particles and produce a clear
filtrate
containing the xanthophylls in the corn-alcohol slurry from the extraction
step 2.
The clear filtrate from step 3, or step 2 if the extraction removes
large particles, is then subjected to membrane nanofiltration step Via. The
3

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nanofiltration step 4a is conducted with a membrane pore size designed to
retain
the xanthophyll molecules, i.e. about a 200-600 molecular weight cut off.
~anthophyll concentrate results from the nanofiltration step 4a. The alcohol
passing through the nanofiltration membrane may be recycled (step 5) back for
use
in further extraction in extraction step 2.
The basic process of the invention is complete with the extraction of
xanthophyll concentrate in step 4a. Alternative features of the invention,
which
extend the process to permit extraction of additional corn products in the
same
basic process flow of the xanthophyll extraction will now be described. These
features, like optional features discussed previously, are shown in dotted
lines in
the figure.
Solvent extraction, step 1b, is optionally conducted to separate oils
from the corn source prior to the reaction in the extraction step 2. As an
example,
hexane extraction produces a corn oil - hexane miscella. Another exemplary
solvent is isopropanol. Generally, any oil extracting solvent is suitable. The
miscella may then be sent to an evaporator to remove the hexane, or
preferably,
through a nanofiltration membrane to concentrate the oil. The nanofiltration
method provides a low energy way to permit recycling the hexane back into the
hexane extraction step 1 b. Residual hexane is removed by a desolventizing
step 1 c
prior to the extraction step 2. Zein concentrate may also be produced through
an
ultrafiltration step 4b, conducted prior to the nanofiltration step 4a. Corn
solids
from the separation step 3 can also be used for further conventional
processes,
such as to produce DDGS or additional ethanol.
While various embodiments of the present invention have been
shown and described, it should be understood that other modifications,
substitutions and alternatives are apparent to one of ordinary skill in the
art. Such
modifications, substitutions and alternatives can be made without departing
from
the spirit and scope of the invention, which should be determined from the
appended claims.
~1

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Various features of the invention are set forth in the appended
claims.

Representative Drawing