PRODUCTION PROCESS, USED IN PARTICULAR FOR OBTAINING LECITHIN FROM DEHYDRATED EGG

PROCEDE DE PRODUCTION UTILISE EN PARTICULIER POUR OBTENIR LA LECITHINE D'OEUFS DESHYDRATES

English Abstract

Using a process for obtaining useful products from raw materials containing
protein and fat, and in particular for obtaining lecithin from dehydrated egg,
a
solution should be created with which useful products can be extracted in
several stages, special emphasis being placed on the production of lecithin.
This is achieved in that the feedstock, comprising lipids, phospholipids
(lecithin) and proteins, is subjected to a supercritical extraction process
using a
solvent for extracting lipids and flavours, the lipids and flavours being
extracted
from the supercritical solvent by pressure reduction.

Claims

5
claims:
1. Process for obtaining useful products from animal raw materials containing
protein and fat, and in particular for obtaining lecithin from dehydrated egg,
characterised in that
the feedstock, comprising lipid, phospholipid (lecithin) and protein
constituents,
is subjected to a supercritical extraction process using a solvent for
extracting
lipids and flavours, the lipids and flavours being extracted from the
supercritical solvent by pressure reduction.
2. Process in accordance with claim 1,
characterised in that
the degreased feedstock, with its proteins and phospholipids, is subjected to
a
further extraction stage using a supercritical solvent and an organic solvent,
which is liquid under normal conditions, as the entrainer (cosolvent) to
separate the phospholipids from the proteins.
3. Process in accordance with claim 1 or 2,
characterised in that
the extract, comprising phospholipids and the cosolvent, is concentrated and
removed from the system with the help of the solvent, the phospholipids
produced being obtained as solid matter and being dried by the supercritical
medium.
4. Process in accordance with claim 1 or with one of the following claims,
characterised in that
subsequent to the supercritical extraction process, the lipids and flavours
are
yielded from the solvents using pressure reduction.
5. Process in accordance with claim 4,
characterised in that
separation is carried out by single-stage pressure reduction (p s < pkrit) to
extract all solvent-soluble constituents from the overall solvent stream.

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6. Process in accordance with claim 4,
characterised in that
pressure reduction is carried out in several stages to separate different
products at different pressures (P s1 > p s2 >> p s n).
7. Process in accordance with claim 2 or with one of the following claims,
characterised in that
the phospholipids are separated from the proteins at a pressure close to
atmospheric pressure using the cosolvent as the solvent.
8. Process in accordance with claim 2 or with one of the following claims,
characterised in that
the phospholipids are separated from the proteins at high pressure in a
supercritical entrainer extraction process using the supercritical solvent and
the cosolvent.
9. Process in accordance with claim 8,
characterised in that
the entrainer is fed in a range of 0 and 20 % of the volume used in the
supercritical extraction process.
10. Process in accordance with claim 8 or 9,
characterised in that
the phospholipids with the entrainer are separated from the solvent by
pressure reduction (p s < pkrit) such that they are then obtained as a
solution in
the cosolvent.
11. Process in accordance with claim 3 or with one of the following claims,
characterised in that
the entrainer (cosolvent) mixed with the solvent is separated from the solvent
using pressure reduction and both are recycled in the system.
12. Process in accordance with claim 12, particularly for obtaining lecithin
from
egg yolk,

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characterised in that
CO2 is used as the solvent and ethanol or hexane, for example, as the
entrainer (cosolvent).
13. Process in accordance with claim 12,
characterised in that
degreased egg yolk is obtained as an intermediate and egg-yolk oil as the
extract in the first supercritical extraction stage.
14. Process in accordance with claim 13,
characterised in that
the egg-yolk oil obtained as the extract in this stage is separated into a
fraction
which is rich in lipids and in flavours.
15. Process in accordance with claim 13 or 14,
characterised in that
the proteins obtained as the raffinate during the second extraction stage are
made available as egg-yolk proteins.
16. Process in accordance with claims 12 to 15,
characterised in that
the phospholipids, which are obtained subsequent to the concentration and
drying steps in the third stage, are removed from the process as the main
product, lecithin.
17. Process in accordance with claim 16,
characterised in that
the composition, i.e. the content of phospholipids, is varied by the control
parameters of the supercritical extraction process performed during the first
stage.

Description

CA 02288469 1999-11-04
Production process, used in particular for obtaining lecithin from dehydrated
eaa
The invention involves a process for obtaining useful products from raw
materials
containing protein and fat, and in particular for obtaining lecithin from
dehydrated
egg.
It is known that lecithin can be extracted, e.g. from raw egg yolk, using a
solvent, e.g.
using liquid dimethyl ether as described in DE-28 33 371-C3 or in the
corresponding
US-4 157 404. A similar process using solvents which are gaseous under NTP
conditions, is described in DE 32 29 041-A1. A procedure, which is essentially
characterised by heat treatment, is described in US-4 844 926 and US-5 028
449.
The objective of the invention is to create a solution with which useful
products can
be extracted in several stages, special emphasis being placed on the
production of
lecithin.
Using a process such as the one described above, this objective is fulfilled
in that the
feedstock, comprising lipid, phospholipid (lecithin) and protein constituents,
is
subjected to a supercritical extraction process using a solvent for extracting
lipids and
flavours, the lipids and flavours being extracted from the supercritical
solvent by
pressure reduction.
This last stage of the procedure causes extensive degreasing of the feedstock
e.g.
the dehydrated egg, with the aid of the supercritical agent acting at a
pressure
between its critical pressure and e.g. 500 bar and at a temperature between
its
critical temperature and e.g. 100°C. The solvent can be recycled during
the
supercritical extraction process.
The intermediate product, i.e. the raffinate, obtained by this extraction
process is the
degreased raw material with the proteins and the phospholipids which remain in
the
extraction vessel. The degree of degreasing can be varied in accordance with
the
extraction parameters and cycles.

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2
The lipids and flavours can be removed from the solvent as the extract by
pressure
reduction. This is also provided for by the invention.
It should be observed at this point that the "Journal of Food Science", vol.
61, no. 6,
1996, p. 1230 ff mentions that soya flakes can be treated with supercritical
C02 and a
cosolvent. The treatment of animal products containing considerable amounts of
proteins is not referred to in this particular article.
Practical embodiments of the invention referred to in the subclaims are as
follows: In
the second stage of the process, the invention provides for the degreased
feedstock,
with its proteins and phospholipids, to be subjected to a further extraction
stage using
a supercritical solvent and an organic solvent, which is liquid under NTP
conditions,
acting as the entrainer (cosolvent) to separate the phospholipids from the
proteins.
Alternatively, the separation process can be effected at a pressure close to
atmospheric pressure using the cosolvent as the solvent, as is provided for by
one of
the embodiments of the invention.
In this stage the proteins can be obtained as raffinate from the raw material
in the
moist entrainer. The phospholipids remain in the entrainer as the extract in
solution.
During this stage, the raffinate is dried by the supercritical solvent and is
obtained as
the product. The cosolvent can then be separated from the gaseous solvent by
pressure reduction. The solvent can be recycled in this case as well, whilst
the
cosolvent can be collected and fed back to the process.
A third stage provided for enables the extract, comprising phospholipids and
the
cosolvent, to be concentrated with the aid of the solvent and removed from the
system, the phospholipids precipitating as solid matter and dried by the
supercritical
medium. This stage can be implemented under pressure with the solvent in a
supercritical or liquid state.
During this stage, the cosolvent is mixed with the solvent and can be
separated from
the gaseous solvent using pressure reduction, as provided for by the
invention. In

CA 02288469 1999-11-04
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this case as well, the solvent and the cosolvent can, as stated above, be
returned to
the process separately.
Further features, details and advantages of the invention are portrayed in the
following description and in the diagram which shows the process layout in the
form
of a block diagram.
The raw material (1 ) is fed to the first treatment stage (2) in which
degreasing takes
place using high-pressure extraction. This is achieved, for example, by adding
a
supercritical gas as the solvent (3). Once the raw material has been
degreased,
separation (4) can take place by reducing the pressure so that the lipids and
flavours
can be recovered as useful products in the form of an extract or separately in
several
individual extract fractions (5).
The residue (6) remaining in the system is subjected to a second treatment
stage (7)
again using, for example, the supercritical solvent (from 3) and/or a
cosolvent (8),
e.g. ethanol.
The residue (9) from the treatment stage (7), which comprises protein and
cosolvent,
is fed to a drying stage (10). The drying stage can be effected using a
supercritical
solvent. The proteins (11 ) contained therein are obtained as useful products.
The
solvent and the cosolvent are fed in one stream (12) to a separation stage
(13) using
pressure and recycled within the system (represented by lines 14 and 15).
An extract (16) is obtained directly or indirectly from the treatment stage
(7). The
extract comprises phospholipids and the cosolvent and is subjected to a
further
treatment stage (17) in which the phospholipids are concentrated with the
solvent at
high pressure. Cosolvent residues can be removed in an extractive drying stage
(18)
so that the useful product lecithin stream (19) can be withdrawn from the
system.
Just like the solvents and cosolvents originating from stage (18), the
cosolvents
and/or solvents originating from the concentration stage (17) are also fed to
the
separation stage (13) before being fed back to the system via lines (14 and
15).

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4
A solvent separation stage (20) can be arranged downstream of the second stage
(7)
to obtain the extract. This is also shown in the diagram.
Of course, the embodiment described can be altered in a variety of ways
without
deviating from the basic principle. This means that the invention is not just
limited to
the treatment of eggs or dehydrated eggs, but can also, for example, be used
to treat
milk or animal tissue if these are prepared accordingly.

Representative Drawing