Note: Descriptions are shown in the official language in which they were submitted.
Fxoceas for Refining Oil and Fat
FIELD Oh TH$ INVENTION
This inventl,on rAlates to a process far th~ refining
of oil end fat. Mare pa~cttculaxly, ~,t relates to a process
fox the refining of oil and fat, in which an ~nzyme is
allowed to react with the oil and fat in an emulsified
Condition, thereby s~ffecting efficient decomposition and,
thus, removal of phospholipids from the oil and fat to be
treated.
~~bf'~;z,F~OUND OF THE INVLN'~ZON
Oils obtained from the usual oil and fat production
processes by compressing oil-bearing matex~,als or by
extracting oil from the materials and removing the extrgction
solvent (hereinafter, referred to as "crude oils) contain
~,mpurities $uch ar polar lipids mainly composed of
phospholip9,da, as w~11 as fatty acids, pigments, odor
components and the like. Thus, it is necessary to remove
these impurl,ties by a refining process. The refining process
requires a degumming step and an alkali refining step. In
the degumming step, hydration of phogpholip~.ds and the like
is effected by addinr~ hot water to the crude oil and gum
materials ere xemovod by centrifugation. zn the alkali
refining st~p free fatty acids in the degummed oil are
neutrali$ed with caustic soda and removed blr centrifugation.
-v,.
Th~reafter, refining of oil and fat is completed via
a bleaching step in which chlorophyll and the like p~.gmenta
are removsd~by ailo~cing them to be adsorbed by activated
clay, activated carbon or the like and a deodorization step
~.r~ which odor components are removed by vacuum distillation.
In the case of the production of salad oil, a dewaxing step
is optionally employed in order to crystallize arid remove
solid fats, waxes and the like which are apt to be
solidified.
FIowever, in the alkali refining step in which free
fatty acids are neutralized with caustic soda and then
removed by centrifugation, residual phoepholipide axe also
removed, but the step generates so-ca~,led "soap stocks" which
contain a large guantity of accompanying oil. Though a
portion of the soap stocks is used as production material fox
Batty acids, they are treated mostly as industrial waste.
gn addition, in the subsequent neutralization step,
th~ processed oil is washed with hot water in order to remove
soap dissolved in tho oil, thus generating a large quantity
of oil-containing alkaline waste water which must also be
treated.
These d~lkal3, refining and neutralization steps cause
a great loss in the oil and fat yield.
Thus, since the convent~.onal oil and fat refining
process requires comg~lex and time-consuming steps, great
concern has been direoted toward the development of a
. Z -
2~.~~W~
reining proceee whj.ch can be operated more efficiently by
simplification and fi.he like,
With xegard to the omission of the alkali refining
step which genexat;es waste materials and reduces oil yield, a
so-called steam ref~,ning process in which free fatty acids
are removed by vacu.unt steam distillation in the deodorization
step (JP-B-53-38281 for instance), a process in which
degummed oil is treated with an enzyme having phospholipase A
activity (JP-A-2-15397), a process in which a phosphatase is
used (EP-A 0,070,269) and a process in which phospholipasee
A~, AZ and 8 are u$ed (BP-A 0,513,709) have been proposed.
('the term "JP-A" as used herein ms~ane an "unexamined
published Japanese patent application", and the tez~m "JP-$"
means an "examined Japanese patent publication".)
However, the process of J~P-E-53-38281 is limited to
the refining vt low phospholipid oil and fat derived fxom
palm oil and the like materials, and it entails production of
oil and fat containing a large quantity of remaining
phospholipids when applied to a starting material dexived
from generally used oil seed such as soybaan, rapeseed or the
like. Such a product cannot be used commercially becau~e of
considerable colarinc~ and odor generated by heating.
On the other hand, the processes of JP-A-2-153997,
EP-A-0,51,3,709 and E~-A-0,070,2&9 require e~.ther a prolonged
pexiod of time fox reaction'with the oil or a large amount of
enzprne .
- 3 -
~~~?~~~f~
~~~r of Tx~ iN~r~NTZON
An object ar the present invention is to provide at
process for the ref.~,ning of oil and fat by which
phospholipids in thEs oils and fats to be treated can be
decomposed and removed ~fficiently.
The invento~re of the present invention have conducted
intensive studies with the aim of developing an efficient oil
and fat xefining pruoegs composed of simpl,lfied steps, namely
an oil and fat refi,raing process which is not only free from
the aforementioned F~x~oblems involved in the prior art but
also economically a.d,vantageous in terms of reduction of
enzyme cost, savings in washing water and the like and
satisfactory fn vie~~ of the quality of the oil and fat
pxoduced. As a result, the present invention in whioh
phaepholipide in oi~,s and fats to be treated are decomposed
and removed efficiently has been accomplished.
The present invention relates to a process for the
refining of oil. and fat which comprises reacting, in an
emulsified condition, the oil and fat with an enzyme having
activity to decompose glycerol-fatty acid ester bonds in
glycerophospholipids.
Othex objects and advantages of the pxesent invention
wi~,l be made apparent as the description progresses.
bETAIL ~~. DESCRIPTION OF THE d~NVENTION"
the oilo and fats to be treated by the process of the
present invention axe unpurified oils such as crude oils ox
- 4 -
CA 02122069 2003-07-07
degummed oils containing phospholipids in an approximate
amount of from 100 to 10,000 ppm. Sources of oil and fat are
not particularly lirarited, provid~d that th~y arc plant oils
and fate suitable for use in food, such as of~eoybean,
rapese~d, sunflower, cotton send, Safflower, peanut and the
l~.ke.
Th~ enzyme to be used in the process of the present
invention should have activity to decompose glycerol-fatty
ac~.d ester bonds in glyc~rophospholipids. Tllustrative
examples of such enzymes include phos~pholipa8e A1 wh~,ch
hydrolyzes tatty acid ester bonds at the ac position of
glycerol residues of a glycerophospholipid, phospholipase Az
which hydrolyzes fatty acid eater bonds at the ~i position and
phospholipase H (alma called lyeophospholipase) which
hydrolyzes lysoglyce:rophospholipids.
These enzymHr~ having high activity ~xi$t in snake
venom and animal, orgA~ne such as the pancreas and are also
produced by microorganisms b~longing to the genus S~rratta,
Penic,illt~rm or the ;L~Lke.
Suitabxe ~n:~~nes are available coxmnercially. As
typical examples of the enzymes for practical us~, pancreas-.
derived phospholipase AZ such a$ Lecitase*(manufaetured by
Novo) ~.s preferably ue~ed.
According to the present invention, these enzymes are
dispersed or dissolved in writer or an appropriate buffer or
aqueous solution and added to the oil and fat containing
* Trade Mark
~~~.~% ~~
about 100 to 10,000 ppm of phvspholipids: The time of adding
the enzyme sdiut3.oz~ tv the oil and fat is not restricted, but
it is pref~rrad to add the enzyme solution to the crude oil
or degummed oil.
In order to improve contact efficiency between th~
oil and water phasee~, the enzyme reaction is preferably
carried out in an emulsified condition us~.ng a suitable
emulsifier such as a high speed mixer, a homomixer, a colloid
mill, a pipeline mixer, an ultxason~,c dispersion apparatus, a
high pressure homogenizer, a v~.bxatox, a membrane emulsifying
apparatus or the like.
The term ~emalsified condition~ as used her~in manna
a condition in which o~,1 is dispersed in an aqueous
dispersion medium, in the form of fine particles having an
average particle size of from 0,1 to 50 Vim, preferably from 1
to 10 Wn .
zn the usual oil and fat refining process, water is
not used in a large ~,~olume, because it causes increased waste
water volume. HoweoQr, the pxesent inventors have studied on
the effect of enzyme reaction in an emulsified condit~.on and
have found advantages that xncreaged water volume is
effective ~.n: (1) ealhancing the enzyme reaction and transfer
of the enzyme hydro~,yzation pxoducts into the water phase by
increase of the contcict surface between the oil and water,
(2) reduving the load of the emulsifier because there is no
generation of gum which is found in the conventional method
_ g _
CA 02122069 2003-07-07
that reEquires degumming and alkali refining atepe~ and because
there is no increase in viscosity which ie found typically in
W/0 emulsion systems, and (3) separating oil and water easily
and thereby allowing repeated use of the separated enzyme
solution ae it is. As a consequenc~, not only ie there a
savings in the amount of enaymo u4ed, but also it is pos~a3ble
to reduce the amount of water to a lower level than that of
the prior art proc~es by circulat~d use of wet~r.
The amount of ~naym~ to b~ used in the treatment may
be in the range of preferably from 10 to 20,000 units, more
preferably from 100 to 2,000 units, per 1 kg of oil and fat.
Depending on the type of ensyme used, a factor sesential for
expr~ssion of its activity or a factor which increases the
activity, such as calcium ox the like, may be added to the
reaction system. The pH of the enzyme reaction may be
ad~ua~t~d depending on the type of en$yms.used although the
optimum pH in this paoc~se does not always match with the
optizaum pH in enzymoloQy. For example, altough the swine
pancreas-derived phospholipaee AZ (Lecitaae) ua~d i.n Examp~.e
1 has an optimum pH of 8 to 9, it is practical to carry out
the ~nayma reaction at a Slightly acidic pH of 5.5 to 6.5,
because the r~acti.on system is strongly emu~.sifi~d when the
reaction pH exceeds ~3. In addition, since water after its
contact with convent~:onai crude oil has a pH valu~ of 5.5 to
6.5, it is not necessary to~adju~et the pH of the ~nsyme
solution, thus rendering possible sharp reduction on the
* Trade Mark - 7
~~.2j~'~~
burden of a waste water treatment system. AlBO, salts such
as sodium chloride and the like may be added in an amount o~
about 5~ or~~,eas based on the washing water, in order to
enhanc~ separation ref the oil and water phag~s after the
react~,on.
The enzyme treatment may be carried out at a
t~mperature of gen~rxal~,y from 30 to 90°C, preferab~.y from
55°C to 75°C, fox a period of approximatelx from 5 minutes to
hours, a7.though such conditions vary depending on the
optimum tampexa~ture of th~ enzyme used.
The amount of water for use in the dissolution of the
enzyme may b~ 30 weight parts or more, preferably 50 weight
parts or more, per 100 weight parts of oil and fat. I~owever,
since the amount of water exceeding 200 weight parts hardly
enhance the enzyme reaction and the tran$ferring of the
phospholipids from oil and fat, it is more preferred from the
viewpoints of economical point and stable operation that the
amount of water to b~a used is within a range of 50 to 200
weight parts per 100 weight parts of oil and fat.
One unit of activity of each ~nzyme is defined as the
amount of the ens~rme forming 1 micromol of fatty acids within
1 minute in the foi~,owing reaction system.
Hnzyma and Sub$trate:
phospho7,ipaeeis A1 and Azp
phosphatidylcholine (soybean orig~.n)
phospholipaet~ e;
_ g _
~~2~~)~a:~
lyaaphosphatidylcholina (soybean origin)
6ubstrate concentration: 2 mg/ml
Calcium concentration s 6 mM
Reaction tim~ : 5 m~t~utes
Reaction temperatua:~: a 40 °C
Reaction pH : optimum pH of each enzyme
After the enzyme treatment, the enzyme solution is
separated by an apF~ropriate means such as centrifugation or
the like, thereby o~~taining treated oil. in this step, most
of the phosphorus-cc~ntai,n~,ng compounds such as
lysophosphatidylcholine, lysophosphatidylethanolamine,
glycerophosphoryicholine, glycerophosphorylethanolamina and
the like formed by the enzymatic hydrolysis of the gum
content axe transferred into the Water phase and ram4ved from
the oil phae~.
Further, phoepholipids can be remo~red more
efficiently by optionally employing after the enzyme
treatment an additional step in which the treated oil is
washed w~,th (hoty water or a (hot) dilute acid solution, that
is, a refining proo~sss which comprises reacting, in an
emulsified Condition, the oil end fat with ~xn enzym~ having
an actt~rit~r to decorn~,~ose g7,ycerol-fatty acid est~r bonds in
glycerophospholipide and subsequently washing the treated oil
and fat w~.th a wae~hing water.
The amount of the waehl.ng water for use ~.n the
washing treatment may be 3Q weight parts or more, preferably
- 9 -
~~~'~4~~a'v
from 30 to 200 weight parts, per 100 weight parts of the
treated oil and fat. Also, the washing treatment may ba
carried out~at a teanp~rature of 55°C ox more, preferably from
SS to 80°C, zt is preferr~d that the washing is carried out
preferably under an emulsified condition us~.ng an emulsifier
similar to the one used is the enayme treatment,
Although the washing can be effect~d with water,
removal of phospholi.pids can be effectiv~ly made by the use
of an acidic aqueouev solution, preferably an acidic aqueous
solution having a pFt value of 3 to 6. illustrative examplee
of such acidic aquac~us solution include an organic acid such
as ac~t~.c acid or citric acid or a salt thereof and
phosphoric $ci.d or s, salt thereof. More effective removal, of
phospholipids can bs made by the use of a solution containing
1 ~0 100 mM of an ozganic ox inorganic acid such ae acetic
acid, phosphoric arid, citric acid or the like and having a
pFI value of 3 to 6. Salts of the organic or inorganic acid
also.Gan be used. Also, in order to enhance separation of
oil and water cyst~ms after the react~,on, salts such as
sodium chloride and the like may be added to the washing
solution in eon amount of about 5% or less. These enzyme
reaction and wash~,ng steps can be carried out in a mufti-step
or continuous fmshio:~.
phospholipid components remaining ire the o~.l
processed by the abo~ae operntione are extremely small, and
can be further reduced to such a level, that they do not spo~.l
- 10 -
CA 02122069 2003-07-07
the c~ua~.ity of the f~,nal product, by their removal with an
adsorbent such as activated clay, activated carbon or the
lik~ through the subs~du~nt bleachinq step which is carried
out in the usual way.
In add3.tion, an alkali refining et~p is not necessary
in~the process of the present invention, because free fatty
acids remaining in the processed oil are completely removed
by vacuum steam distillation in the deodorizr~tion step.
The following inventive and comparative examples era
provided to furth~~r illustrate the present invention. xt is
to be understood, however, that the examples axe for the
purpose of illustration on~,y and are not intended as a
def init~,on of the 1 l m~.ta of the pres~nt invention . In the
following Examples and Comparative Example, phospholipid
ana~.ysis was carried out in accordance with the procedure of
Japanese Standard Oii and Fat Analysis 2..2,8.1-71.
A 1.5 kg portion of unpuxified soyb~an vil
(phospholipida, 2,900 ppm) was mixed with 1.5 liters of an
en$yme solution (Lecitase, manufactured by Navo; 200 units
per liter of solution containing 5 mM calcium; chloride and
mM citric acid, pH 6), and the mixture was subjected to
2 houre~ of reaction ~at 60°C with stirring at 10,000 rpm using
TR homomixer (MARR-II Z.5 typ~, manufactured by Tokusht~ Itika
l~ogyo) . Alter cornpl~etfon of the reaction, the ~n$yme
solution was removed by 5 minutes of centrifugation at
- 11 -
* Trade Mark
i
CA 02122069 2003-07-07
1,500 G, thereby obtaining an enzyme-treated oil containing
3x4 ppan of phoepho~,~lpids. N~xt, the thus tr~ated oil was
washed for 1.0 minutes with 1.5 liters of 100 mM citric acid
solution (pH 4) under the same sti,xring condition emp~.oyed at
the time of,the ~nxyrae treatment. Aft~r centrifugation and
subsequent vecuunt dewatering of the resulting oil, the thus
dewatered oil was mixed with 1.0 wt% activated clay (NV,
manufacturer3 by Misusawa Kagaku Xogyo) and subjected to 24
minutes of bleaching at Z05°C under 30 mmHg to obtain a
bleach~d viI containing x7 ppm of phospholipids.
The process of Exampl~ 1 Was xepeated except that the
oil wag treated with 45 ml of an enzyme solution (670,000
units per liter of solution containing 5 mM calcium chloride
and 100 mM citric acid, pH 5) and the washing treatment was
not carried out, thereby obtaining a bleached oil having a
phospholipid content of 950 ppm.
In comparinr~ Example 1 With Comparative Example l,
the phospholipid con~~tent after the enzyme reaction in an
emuleivn was 3i0 ppm in Example 1, which was 3 times lower
than that (950 ppm) after the bleaching in Comparative
Example ~, (corresponding to Ep-A..0,513,709), and the content
after the b~.eaehing was only 27 ppm in Example 1 which was
about 35 times sup~r~.or to th~ cass~ of Comparat~.vo Example 1.
~~~Fs 2
- 1~ -
i
CA 02122069 2003-07-07
A 1.5 kg portion of unpurified soybean oil
(phospholipids, 2,500 ppm) was mixed with 1.5 liters of an
enzyme solution (L~ecitas~, manufactured by Novo; 20, 000 units
per liter of solution containing 5 mM calcium chloride), and
the m~.xture was subject~d to 2 hours of reaction at 60°C with
stirring at 10,000 :rpm using a TR homomixer (MARK-II.Z.S
type, manufactured by Tokushu Rika Kogyo). After completion
of the reaction, the o~.l phase recovered by centrifugation
was subs~cted to the bleaching in the same manner as in
Example 1. Thereafter, the phospholipid content i.n the thus
bleached oil of this example, and all remaining examples and
comparative examples was measured ~.n the same way cg in
Example 1.
A bleached oil was obtained by repeating the proc~ss
of Example 2 except that concentration of the enzyme was
changed to 2,000 units/liter (Lecitase; manufactured by Novo;
a solution contain,~ng 5 mM calcium chloxide).
Enzyme treatwnent was carried out in the same manner
as described in Exaanple 2 except that concentration of the
enzyme was changed to 200 units/litex (Lecitase; manufactured
by Novo; a so~,ution ~~ontaining 5 mM calcium chloride), the
enzyme solution Was ;removed by centrifugation and then the
resulting oil was waa~hed w~,th I.5 liters of water for 10
minutes under the sane temperature and stirring conditS.on$ as
- 13 -
* Trade Mark
r
.~.r~~~~~9
used in the enzyme tr~atment. After centrifugation, the
resulting oil was subjected to bleaching under the same
conditions ae described in Example 1, thereby obtaining a
bleached oil.
EXAMPLE 5
A bleached oil was obtained by repeating the process
of Example 4 except that a 10 mM satric acid solution (pH
adjusted to ~.0 with sodium hydroxide) was used as the
wa~hing so~,ution iaxfstead of water.
,~$ PAMPAM LE 66
R bleached oil was obtained by repeat~.ng the process
of Example 4 except that a 10 mM phosphoric acid solution (pH
ad~uated to 4,0 witra sodium hydroxide) wa~ used ae the
washing solution instead of water.
EXAMPLE 7
A bleached ail was obtained by repeating the process
of Example 4 except that a 10 mM acetic acid solution (pH
adjusted to 4.0 with sodium hydroxide) wag used as the
washing solution instead of water.
ARA,T SAE EXAMPLE 2
A bleached oil, wasp obtained by repeating the same
enzyme treatment and bleaching as described in example Z
except that a mixer (250 rpmj ec~ul,pped with a propeller
agitation blade of 60 mm in diameter Was used.
- 14
COMPARATIVE EXAMPLB :~
:A bleached oil was obtained by repeating the process
of Example 7 except that the enzyme was not added.
The phospholipid contents in these bleached oils
obtained above axe shown in Table 1.
TA8
Remaining
Enzyme waehinc~ Phospholipids
Mi~ce~, U 1 Solution . Lunm~
Examp7,e 2 TR homo 20,000 - 50
Example 3 TK homo 2,000 - 145
Exampl~ 4 TIC homo 200 water 44
$xampla S TR homo 200 phosphoric 26
acid
Example 6 TR hamo 200 citric acid ~,8
Example 7 TK homo 200 acetic acid 21
Comparative propeller 20,000 ' 8'f0
Rxample 2
Comparative TR hcmo 0~ acetic acid 1,540
Bxa~mple 3
(totes]
Mixer Tit homot xx xomomixex MARK-II 2.5 Type
Propellers a propeller type agitation blade
A$ is evident from the aompaxative results shown in
Example 2 and Compart~tive Example 2 (coxg~sponding to JP-A-2-
15399~j, the use of an appropriate mixing emuls~Lfier rendered
po~sible ~.mprovem~nt of enzyme reaction eff~.c~.ency and
dxastie reduotion of phospholipids remaining in bleached
- 15 ..
CA 02122069 2003-07-07
oils. In addition, the quantity of en$yme used was
economized by the ~.:ntroduct~,vn of a washing step, and it was
suxprised that the Hxuantity of enzyme could be economised by
1/x00. The effect of the present invention wa$ further
improved by the additl.on of an inorganic or organ~.a acid such
as phosphoric acid, nitric acid, acet~,c acid or the like to
the washing solution. Since enzyme cost is a significant
factor in enzyme-aided phospholipid removal processes, thecae
effects of the present invention are highly valuable.
A 2 kg port~,on of unpurified soybean oil
(phospho7.ipida, 2,2Q0 ppm) was mixed with 1 lit~r of an
enzym~ solution (Lecitase; manufactured by Novo; 404 unite
per liter of 5 mM calc~.um chloride solution containing 2%
avdium chloride), and the~mixture was subjected to 2 hours of
x
reaction at 70°C with stirring at 10,000 rpm using CleaMix~
(CLM-L 2.58, manufactured by M T~chnique). After completion
of the reaction, th~ oil phase was recovered by 5 minutes of
centrifugation at 1,.500 G and washed with 2 litexs of ZO mM
citric acid solution (pH 4) containing 1% sodium chloride.
The washing was carr:led out for 10 minutes under the same
stirring and temperatuxe conditions as used in the enzyme
reaction. Thereafter, bleach~.ng was carried out in the same
manner as described in Example 1, and the resulting oil was
used as a fixst treated oil:
- 16 -
"' Trade Mark
CA 02122069 2003-07-07
Using the a:pent enzyme solution and washing solution
recovered in the abovA process, 2 kg of another unpurified
soybean oil~(phospholipids, 1,800 ppm) was purified in the
same manner to be uoed as a second treated oil,
Phospholipids contained in the f~.rst and second
treated oils wer~ 2x ppm and Z8 ppm, respectively. Thus, the
enayme solution and washing water could be repeatedly used.
ERAMPLB 9_
A 50 kg portion of unpurified rapeseed oil
(phospholipids, 5,400 pp~m) was mixed with 50 liters of an
enzyme evlution (Lecitase, manufactured by Novo; 1,000 units
per liter of 5 mM calcium chloride solution containing 2%
sodium chloride), and the mixture was subjected to 2.5 hours
of reaction at 65°C with stirring at 3,600 rpm using a TR
Homomixsr (MRRiC-II 160, manufactured by Tokushu Rika Rogyo).
After completion of the reaction, the oil phase was recovered
on standing and washed with 50 liters of 10 mM acetic acid
solution (pH 4). Tha washing was carried out for 10 minutes
under the same stirring and temperature conditions as used in
the enzyme reaction. A 1 kg portion of the resulting oil
separated on etandinc~ was dewatered by centrifugation.
Thereafter, bleaching was carried out in the same manner as
described in Example 1 except that the amount of activated
clay was changed to 2.5%, and the resulting oil was further
subjected to deodorization at 255°C under 8 mmtig with a steam
blowing xatio of 1.5 g/kq oil. The product oil contained 38
_ 17
* Tie Mark
ppm of phospholipids and was excellent in quality in terms of
taste when cooled, odor when heated, coloring when heated and
the like,
EXAMpL~ 10
A 1.5 kg portion of unpur~.fied safflower oil
(phoaphol~.p~.de, 5,000 ppm) was mix~d with 3 kg of an enzyme
relution (50 units/liter of bee toxin pho~pholipase Az,
manufactured by Boehringer-Mannheim), and the mixture was
o~,rculated for 30 minutes through a Harmonizex (manufactured
by Nanomi,zer) at 40°C under a pressure of 9 kg/cmz. After
centrifugation, to the resulting oil was added 2 liters of
mM acetic acid (p1i 5), and the mixture was circulated eat
80°C for 10 minutes through a Harmonizer. The oil obtained
by centrifugation wus subjected to bleaching in the same
manner ass described in Example 1 to obtain a bleached oil
contain~,ng 20 ppm oi: phospholipide.
'thus, as has been described in the foregoing,
according to the process of the present invention, oil and
fat can ba purified without employing the conventional alkali
refining step which causes a serious problem of generating
waste water and industrial waste containing a large quant~.ty
of oil. Because of thin, generation of industr~,al wastes
such as soap stocks and washing wast~ water specific far
alkali refining, as well as loge of neutral oil and fat due
to their inclusion in theee'waates, can be reduced in the
process of the present invention, thus resulting in yield
- 18 -
improvement and xeeiuction o~ oil and fat refining costs as a
whole,
While the invention has been described in detail and
with reference to specific examples thereof, it wall be
apparent to one skilled in the art that var~.oue changes and
modificat3.ons aan be made therein without departing from the
ep9.rit and scope thereof.
- 19
