Note: Descriptions are shown in the official language in which they were submitted.
2 ~
A process for the production of a vegetable-oil product
The present invention relates to a process for the production
of a vegetable-oil product from oilseed, in which process the
seed is comminuted and slurried in water and the slurry is
treated so that the oil is detached fxom the seed tissue,
whereafter the oil is separated from the aqueous phase and is
refined to produce the final product. In addition, the inven-
tion relates to a vegetable-oil product produced by the pro-
cess.
Conventional methods for preparing vegetable oil are based on
the separation, by axtraction,.of the oil :~rom the other con-
stituents of the seed. Before the extraction step, crushed
seed is heated and pressed, and in certain cases -these steps
may substitute for the extraction. Organic solvents, such as
hexane, have been used for the extraction~
The disadvantages of oil separation by extraction include the
high capital costs of the necessary equipment, as well as high
operating costs. In addition, solvent residues which may con-
stitute a safety and health hazard and to which maximum values
have therefore been set in legislation are left in the oil ob-
tained and also in the seed material which is left over from
the separation and is used for fodder.
In addition to the above-mentioned disadvantages, the pressing
and extraction process involves a problem in that the phospho-
lipids, i.e. phosphatides, pre~ent in the seed end up in the
extract, together with the oil. In this case the phosphatides
must be removed from the oil in the first step of the refining
so that they will not disturb the subsequent steps of the re-
fining, in which the oil is purified of aldehydes and of freefatty acids, as well as of pigments.
The removal of phosphatides as part of oil refining has most
commonl~ been carried out by using water or an acid. In each
case, owing to their amphoteric character, the phosphatides hy-
drolyze and become insoluble in oil. Thereupon they can be sep-
arated from the oil by centrifugation, for example. Other meth-
ods for removing phosphatides include the use of membranes ac-
cording to GB Patent 7 421 813 and the adsorption methods
using bleaching clay or silica according to US Patents 635762
and 823217.
The object of the present invention is to provide a method sim
pler than previous ones for the preparation of a vegetable-oil
product, eliminating the separate phosphatide removal step be-
longing to the refining. The process according to the inven-
tion is characterized in that an enzyme is added to an aqueous
slurry of the seed so that the oil is separated under its ac-
tion to form a separate phase, while the phosphatide present
in the seed remains mainly in the aqueous phase, that the oil
phase is separated and that the separated oil is transferred
directly to physical refining, which consists of a treatment
with an adsorbing agent and/or of deodorization.
What is accomplished with the enzyme addition according to the
invention is that, as early as the primary oil separation
step, the phosphatides remain in the aqueous phase left over
from the separation, whereupon the obtained oil phase can, sub-
stantially without intermediate steps, be transferred to the
subsequent physical refining. For the physical refîning there
suffices, according to need, an adsorption treatment mainly
for the removal of pigments and/or a deodorization for the
removal of the aldehydes or free fatty acids present. Since
~5~
the separation of the oil phase from the aqueous phase can be
by mechanical means, for example, by centrifu~ation, the use
of an organic solvent for the extraction of the oil is avoided
in the invention, as is also the separation of the oil from
the solvent, and an oil is obtained which is completely devoid
of hazardous solvent residues.
The mechanism of the enzyme action, which in itself in no way
restricts the invention, in the separation of oil and the
other constituents of seed according to the invention is
obviously as follows~ In seed, such as rapeseed, oil is pres-
ent in the cytoplasm of the seed tissue, in the form of small
bodies separated from each other by monomolecular phosphatide
layers. Under the action of the enzymes, the said walls be-
tween the bodies are hydrolyzed, breaking down so that the oil
can separate from the cytoplasm. The hydrolyzing phosphatides
at the same time become insoluble in the oil phase. The phos-
phatides thus remain, dissolved, in the aqueous phase and are
separated from the oil definitively in the centrifugation or
other such mechanical separation. According to the observa-
tions made, an oil phase which has been separated according to
the invention by an enzyme treatment and centrifugation has an
even lower phosphatide content than has an oil which has been
separated from seed by conventional prior~art methods and has
been treated separately for the removal of phosphatides.
With respect to the state of the art it should be noted that
the use of enzymes in the treatment of oilseed is not in it-
self novel but a procedure known per se. For example, GB Appli-
cation 2 127 425 discloses a method in which an enzyme is used
to promote the extraction of oil by means of hexane. Further-
more, enzymes have been used in the separation of coconut oil
(Mc Glone et al~ J. Food Sci. 51, 1986, pp. 695-697) and avoca-
do oil (Buenrostro et al., Biotechnol. Lett. 8, 1986, pp. 505-
506). However, the literature contains no mention of the ac-
tion of enzymes on phosphatides, and there is no information
given on the phosphatide contents in oils separated ~rom seed
by using enzymes. The separation of oil would thus be followed
by a conventional refining treatment with the conventional
steps for the removal of phosphatides, the adsorption of pig-
ments, and the deodorization of the oil. By contrast~ in the
present invention, which i5 substantially based on the action
of enzymes on the phosphatides present in the seed, it is es-
sential that the obtained oil phase is transferred, without
any separate steps for the removal of phosphatides, directly
to the physical step of the refining, in which the oil is
given an adsorption treatment and/or is deodorized.
The first step of the process for the preparation of a vegeta-
ble oil product according to the invention is the comminution
of the seed, for example by flaking or by coarse milling.
Thereafter the seed is preferably heated so that its inherent
enzymes are destroyed. Thus it is ensured that the action of
the subsequently added enzyme acting on phosphatides will not
be disturbed and that the enzymatic reactions will occur in
the desired manner, with control. After the heating, the
comminution of the preliminarily comminuted seed is continued
using a disc attrition mill, a pin mill or some other fine-
milling equipment. The finely milled seed is slurried in
water, and the slurry is cooked for 10-60 min, preferably 30-
40 min. If the cooking is continuous, the solids content of
the slurry may be within the range 20-70 ~, preferably 40-50%.
On the other hand, if batch cookers are used for the cooking,
the solids content of the slurry may be within the range 10-
60%, preferably 15-40 %. After the cooking,the slurry can be
wet milled by using, for example a colloid mill. After
possible dilution and cooling, the slurry is ready for the ad-
dition of the enzyme having ~ction on phosphatides.
2 ~
The enzyme used has typically some optimal pH value to which
the slurry is adjusted by adding an acid or a base. Thereafter
the enzyme is added in a dose which may be 0.1-5.0 % by
weight, most commonly 0.5-3.0 % by weight of the solids of the
slurry, depending on the type of the seed and the en~yme used.
After the adding of the enzyme, the slurry is incubated at the
operational optimum temperature of the enzyme for 0.5-6 hours,
preferably 3-4 hours. In this context it should be pointed out
that the optimum conditions for the enzyme action in the pro-
cess according to the invention are not necessarily those re-
ported by the enzyme manufacturer on the basis of his charac-
terizational studies; they have to be determined separately by
experimentation. The enzymes used may vary according to the
complexity of the cell walls of the seed; multi-activity
enzymes have proven to be suitable, although carbohydralases
have also yielded good results.
By the end of the incubation step, the desired division of the
material into an oil phase, an aqueous phase and the remaining
solids of the seed has taken place. By the use of the enzyme
it has, according to the invention, been accomplished that the
phosphatide present in the seed has in the main hydrolyzed and
passed into the aqueous phase. The incubated slurry is heated
to the temperature range 50-95 ~, preferably 70-95 C, and is
centrifuged in a decanting vessel in order to remove the solid
seed material and any oil drops possibly adhering to it. The
remaining li~uid phase is maintained at a temperature of
70-95 C and is clarified in a clarifier centrifuge, in which
solid material will still separate out from the liquid. The so-
lids obtained from the decanter are reslurried in water at a
temperature of 60-~0 QC, and the seed hulls are separated
using a vibratory screen. The separated hulls are drained,
pressed to dewater, and dried. The solids separated in the
clarifier centrifuge are slurried in the washing water which
~ ~
has passed through the vibratory screen. The obtained slurry
is heated to the temperature range 60-80 C and is divided in
the clarifier centrifuge into a solid phase and a liquid
phase. The liquid phases obtained form the clarifier in the
said two steps are pooled together, maintained at a tempera-
ture of 50-95 C, preferably 70-90 C, and divided in a puri-
fier centrifuge into an oil phase and a liquid phase. The so
lids obtained from the clarifier are homogenized and dried
using, for example, a spray drier. To the obtained oil phase
there is added, at a temperature of 30-70 C, preferably
40-60 C, approx. 0.1-3 % filter aid mixed with 0.1-0.5% so~
dium sulfate, whereafter mixing is carried out in a mixing
tank. The oil is filtered using a conventional filter, such as
a plate filter, and, when so desired, it can be further dried
in a vacuum dryer. The phosphatide content in the oil obtained
is so low that, after this, a mere physical refining treatment
will suffice, without the chemical step normally carried out
for the removal of phosphatides.
The physical refining of the oil may comprise, as the first
step, an adsorption treatment in which, by using siliceous
earth or other similar adsorption agent, mainly pigments and
possibly remaining phosphatides are removed from the oil. The
duration of the treatment may be, for example, 50 min. There-
after the oil can be subjected to deodorization, which may be
carried out, for example, by blowing steam through the oil for
approx. an hour at a temperature of approx. 250 C. The deodor-
ization removes from the oil free fatty acids, aldehydes and
Gther oxidation products, and the oil obtained is ready for
use, for exampl~, as a foodstuff.
~ 3
Example 1
Low-glucosinolate rapeseed (Westar) were flaked and steam
cooked at 95 C for 30 min in order to inactivate the myro-
sinase enzyme inherently present in the seed. The cooked,
flaked seed was thereafter comminuted in a disc attrition mill
fitted with serrated discs. A slurry with a solids content of
40 % was prepared from the comminuted seed, and this slurry
was cooked for 30 min. The slurry was then diluted with cold
water to a 20 % solids content, whereby the temperature of the
slurry was also lowered. The pH of the slurry was adjusted to
4.0 by using acetic acid. Thereafter, an enzyme mixture con-
sisting of the enzymes Novo SP-249 and Pectinex 3XL was added
to the slurry at ~ % of the dry weight of the slurry, and the
slurry was incubated at 45 C for 24 hours. After the incuba-
tion the slurry was heated to 80 C and was centrifuged in a
laboratory centrifuge so that -three separate phases were ob-
tained, i.e. the solid sediment, the aqueous phase, and the
oil phase. The aqueous phase was centrifuged in a bucket cen-
trifuge, whereby a solid sediment not containing hull material
and an aqueous phase containing practically no oil were ob-
tained. The solid sediments obtained in -the centrifugation
operations were resuspended in water at 70 C and were cen-
trifuged once more into three separate phases. The two oil
phases obtained in the centrifugation operations were pooled
together, and a mixture containing filter clay 1 % by weight
of the oil amount and sodium sulfate 0.2 % by weight of the
oil amount were added to them. The oil was mixed at 50 C,
whereafter it was filtered. The obtained crude oil was finally
dried under vacuum. The measurement re~ults characterizing the
quality o~ the oil are given in the following table.
Table
Process Peroxide Iodine Free fatty Chlorophyll Phosphate
value value acids
(meq/kg) (cg/lOOg) (%)tppm) (ppm)
Solvent
extraction 3.1 117.5 0.80 21.5 121.5
Process of
Example 1 7.8 116.1 0.77 18.4 2.9
The reference process in the table is a solvent extraction in
which the oil was produced in a laboratory, by using Soxhlet
apparatus, from the same heat treated and flaked seed as in
the enzyme process, by using hexane as the solvent.
Example 2
Rapeseed ~Westar) was treated for the adding of the enzyme as
in Example 1. After the cooking and dilution, the pH was ad-
justed as in Example 1 and the temperature was maintained at
50 C. Enzyme Pectinex 3XL (Novo) was added to the slurry, and
the slurry was incubated for 4 hours. After the incubation the
oil was separated as described in Example 1. The measurement
results characterizing the quality of the oil are presented in
the following table.
Table
Process Peroxide Iodine Free fatty Chlorophyll Phosphate
value value acids
(meq/kg) (cg/lOOg) (~)(ppm) (ppm)
Process of
Example 2
(Pectinex
3XL) 10.2 116.0 0.55 19.51.8
Example 3
Low-glucosinolate rapeseed (Tobin), which differed from the
seed used in Example 1, was treated for the adding of enzyme
as described in Example 1. After the cooking, the slurry was
wet milled in a Siego mill. The milled slurry was dilutPd to a
solids content of 20 %, the pH was adjusted to 4.5 and the tem-
perature to 50 C. Enzymes Olease ~Biocon) and Pectinex 3XL
(Novo) at 2 % by weight of the solids of the slurry were added
to the slurry. The slurry was incubated for 4 hours, and the
oil was separated as described in Example 1. The measurement
results characterizing the quality of the oil obtained are pre-
sented in the following table:
Table
Process Peroxide Iodine Free fatty Chlorophyll Phosphate
value value acid~
(meg/kg) (cg/lOOg) (~) (ppm) (ppm)
Process of
Example 3
(Olease +
Pectinex
3X~) 4.6 115.2 l.O 19.1 1.2
Example 4
Rapeseed (Tobin), which was the same as that used in Example
3, was treated for the adding of enzyme as described in Ex-
ample 1. After the cooking and dilution, the pH was adjusted
to 5 and the temperature to 50 C. Olease (Biocon) at 2 % by
weight of the solids of the slurry was added to the slurry,
and the slurry was incubated for 4 hours. After the incubation
the oil was separated as described in Example 1. The measure-
2~ ~&9~$
ment results characterizing the quality of the oil obtainedare presented in the following table:
Table
Proces~ Peroxide Iodine Free ~atty Chlorophyll Phosphate
value valueacids
(Il)eq/kg) (cg/100~) (96) (ppm) (ppm
Process of
Example 4
tolease) 3.9 115.90.82 14.0 1.4
Example 5
Rapeseed (Westar) was treated for the adding of enzyme as de-
scribed in Example 1. After the cooking and dilution, the pH
of the slurry was adjusted to 4.5 and the temperature to
50 C. The enzyme mixture according to Example 1 at 2 % by
weight of the solids of the slurry was added to the slurry,
and the slurry was incubated for 4 hours. The oll was separ-
ated as described in Example 1, and its quality charac-
teristics were determined. The measurement results obtained
are presented in the following table.
Thereafter the oil was sub]ected to a physical refining, at
the beginning of which the oil was treated with 100-400 ppm ci-
tric acid at 60 C for 20 min. Adsorption clay was added to
the oil, and tbe oil was maintained at 100 C under a pressure
of 310 kPa generated by using an inert gas. After the adsorp-
tion step the oil phase was deodorized under a pressure of 0.4
kPa at 245 C by blowing steam through it for one hour. Fi-
nally the oil was cooled, clarified by filtering it with clay,
and analyæed by measuring the parameters characterizing the
quality of ths oil. The measuremen-t results are presented in
the following table.
Table
Process Peroxide Iodine Free fatty Chlorophyll Phosphate
value value acid~
(meqJkg) (cg/lOOg) (%) (ppm) (ppm)
Proces~ ~f
Example 5
Crude oil 0.44 119 0.74 17.1 3.0
Physically
refined oil 0.00 117 0.04 0.0 <0.2
The examples show that the phosphorus content of the crude, un-
refined oil was in all cases at maximum 3 ppm. In conventional
rapeseed oil production processes, the upper limits of phos-
phorus for degummed and superdegummed oils are 200 ppm and 50
ppm (Canadian General Standard Board). The phosphorus content
of the crude rapeseed oil obtained according to the invention
is thus only a fraction of the said values, and also consider-
ably lower than the upper limit, 15 ppm, set for refined rape-
seed oil (Canadian General Standard Board). It can be seen
from the results of Example 5 that in the physical refining
step of the process according to the inventLon the phospho:rus
content of the oil further considerably decreases~
It is evident for an expert in the art that the different em-
bodiments of the invention are not restricted to the examples
presented above but can vary within the accompanying claims.
Thus it is possible to use, instead of the rapeseed cultivars
used in the examples, other types of oilseed, such as sun~
flower seed or soybean or cotton seed, or even corn.
