Note: Descriptions are shown in the official language in which they were submitted.
~ 1 ~2655
PROCESS TO MAINTAIN BLAND
TASTE IN ENERGY EFFICIENT
OIL DEODORI~ATION SYSTEMS
Edward S. Seguine
Background of the Invention
In order to build superior taste into edible oil
products, they must undergo certain processing steps.
The most important, from a finished flavor standpoint,
is deodorization. Since the senses of taste and smell
are closely linked, deodorization also improves the
flavor of the product. The finished product is ideally
a bland oil.
About the middle of the last century, deodorization
of fats was practiced in Europe by blowing steam through
the heated oils. Prior to the turn of the century,
steam blowing was used in connection with evacuation
for the improvement of fats used in margarine products.
About 1900 David Wesson, in the United States, designed
a greatly improved steam-vacuum deodorizer. The system
success~ully avoided air contamination, which is one of
the important prere~uisites of ~his high-temperature
;~ treatment. The process was never patented, but its
secrecy was so effectively guarded that for a great
~; 20 many years competitive efforts failed to match the
quality of the products that were treated in the Wesson
system.
In addition to improved batch processes, semi-
continuous and continuous deodorizers were later
developed. ~he theoretical aspects of steam stripping
are governed by RaouLt's law and Dalton's law.
Vernon Young in an article published in Chemistry
and Industry Sept. 16, 1978, p~. 692-703, provides an
excellent review of processing currently in use for
refining and modifying oils and fats.
, .
~ 172~55
High temperature deodorization systems require
large ~mounts of energy, but they can be designed
for heat recovery to save energy. For e~ample, a
deodorizing system modification for heat recovery and
steam refining of palm oil is reported by Gavin et al
in J. Am. Oil Chemists Soc., November 1973 (Vol. 50),
pp. 466A-472A~
Also, U.S. Patent 3,607,670, ~ing, Sept. 12,
1971, relates to a deodorization process in which the
heat exchange between incoming cold oil and outgoing
hot oil takes place within an enclosed vessel.
The problem of bland oil regression (degradation),
however, is a drawback to energy efficient deodorization
systems, and paxticularly prior art modified systems
where hot, freshly deodorized oil i5 held dormant, dwells
or is pumped out of the deodorizer at too high a
temperature. Such oils degrade from a bland ta~te to a
scorched or rubbery taste, or degrade to various other
$i~vors which are less than bland.
Thus, there was a need to in~ent a process whereby
optimum heat is utilized and the bland taste of deodorized
oil is maintained in energy efficient systems.
It is~an obje~t of the present invention to
prevent degradation of ~land flavor in hot, freshly
deodorized oil in high temperature deodorization
systems where said oil is held dormant fox further
processing.
It is another object of the present invention
to provide a method to maintain optimum good taste and
bland flavor in freshly deodorized oil.
Another object of the present invention is to
maximize heat recovery in high temperature deodorization
systems while maintaining bland deodorized oil flavor.
Other objects will become apparent in the light
of the disclosuxe.
.
,~ ,. .
:
1 ~726~5
--3--
: Brie Descriptlon of the Draw ng
The Figure is a pictorial schematic of a contin-
; uous deodorizer unit ln which this invention is
illustrated.
Summary of the Invention
In view of the above-stated need, the present
invention provides a high temperature edible oil
deodorization process which utilizes a vacuum deodoriza-
tion system, said process comprising the steps of:
(a) stripping odoriferous constituents from said
: o.il at a high temperature to provide a hot,
: freshly deodorized oil having a bland flavor,
: ~ said hot, freshly deodorized oil having a
~ temperature of above an outgoing oil bland
flavor-stable temperature; and
(b~ cooling said hot, freshly deodorized oil to
~: a storage temperature;
the lmprovement comprising utilizing a cooling
: means to quench said hot, freshly deodorized oil to a
pumpable outgoing oil bland flavor-stable processing
: ~ temperature.
: : :
Furthermore, the present invention provides a
process for utilizing heat and xecovering energy in
, :~
hot, freshly deodorized outgoing oil in a deodorization
system wherein the hot deodorized outgoing oil is utilized
to warm up cold undeodorized incoming oil via a heat
interchanger means, said process comprising the steps
~ of:
: : (a) deodorizing said incoming oil at a temperature
;~ 30 of ahout 425F to about 520F to provide said
~:~ hot, freshly deodorized oil having a tempera-
ture above a hot pumpable outgoing oil bland
: flavor-stable processing temperature;
: (b) utilizing a cooling means to quench said hot,
freshly deodorized outgoing oil to said hot,
pumpable outgoing oil bland flavor-stable
processing temperature of from about 480F to
about 340F dependinq on the type of oil and
dormant time prior to coolingi and
~ 1 7265~
(c) passing said hot, pumpable outgoing oil
through said heat interchanger means to warm
up said cold undeodorized incoming oil.
Detailed Description of the Invention
S mis invention relates to an i~pro~E~t in a high t~rature
edible oil, deodorization process which utilizes a
vacuum deodorization system, said process comprising
the steps of:
`~ ~a) stripping odoriferous constituents from said
oil at a high temperature to provide a hot,
freshly deodorized oil having a bland flavor,
said hot, freshly deodorized oil having a
. temperature of abo~e an outgoing oil bland
: fla~or-stable process temperature; and
(b) cooling said hot, freshly deodorized oil to a
storage te~perature,
the improvement comprising utilizing a cooling
means to quench said hot, freshly deodorized oil to a
p~lmpable (outgoing oil) bland flavor-stable processing
t~mperature (PBFSPT).
The invention further relates to a deodorization
syste~ which operates with said hot, freshly deodorized
oil at a high oil temperature of from about 425F to
about 520F, and at a pressuxe of from about 0.1 mm o
: 2S mercury to about 30 mm of mercury absolute pressure
:: prior to said quenching, and wherein said outgoing oil
is quenched to said pumpable bland flavor-stable proces-
: sing temperature of from about 480F t~ about 340F,
and wherein ~aid quenched oil is further cooled via
: 30 heat interchanger means within 30 seconds to about 10
minutes after said ~llench, and wherein said deodorization
temperatuxe and said pumpable temperature, and said time
be~ore said further cooling are interdependent upon the
type o~ oil being processed and the type of deodorization
system being use-~.
1 ~ ~2~5~
Preferably, the oil is deodorized at a high oil
temperature of from about 460F to about 490F, and
the outgoing oil is quenched to a pumpable temperature
below about 446F within a quench time of about a
fraction of a second to about S0 seconds.
In a preferred embodiment, the process of this
invention preferably comprises the steps of:
(a) feeding said hot incoming oil into a deodoriza-
tion vacuum column, deodorizing said incoming oil at an
oil deodorization temperature of from about 446F to
about 520F by passing super-heated stripping steam
countercurrently through a separate upper deodorizing
section of said column, said hot, freshly deodorized
oil dropping into a separate lower reservoir of said
column;
(b) utilizing said separate lower oil-sealed
reservoir in said column as a conduit for said hot,
deodorized outgoins oil as it passes into said lower
reservoir to be pumped;
~ 20 (c) utilizing a cooling means in said lower
- reservoir to quench the temperature of said hot, freshly
deodorized outgoing oil down to said pumpable oil temp-
erature of below about 446F within a quench time of
; about a fraction of a second to about 50 seconds.
The preferred cooling means for quenching the oil
is previously deodorized cooled quenching oil brought
in contact with said hot, fxeshly deodorized oil.
Preferably, the quenching oil is directly mixed with
said hot outgoiny oil as the hot outgoing oil passes
into said lower, oil-sealed reservoir. Furthermore,
the preferred hot, freshly deodorized outgoing oil has
a temperature o from about 460F to about 490F when
it passes into t~e lower, oil-sealed reservoir, and
said quenching oil has a maximum temperature of about
140F. In another preferred embodiment, a pool or
outgoing oil in said oil-sealed reservoir is agitated
with stripping steam.
~ ~7~6~5
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The deodorizaticn steam temperature is not critical,
and can r~nge from about the boiling point of water at
the inlet pressure to about 600~F. Water can even be
introduced in lieu of steam, since the water would be
immediately vaporized and heated to the deodorization
temperature by contact with the hot deodorized oil in
the lower portion of the deodorization column 1 and any
other hot materials which the water contacts. It cools
the apparatus and makes deodorization less efficient.
On the other hand, steam at a temperature in excess of
about 600F can scorch the oil, and it is unnecessary
to use such high temperature steam. It is preferred
that the steam temperature be within about 20F of the
oil temperature; cooler steam cools the oil, and hotter
steam is unnecessary. Thus, the preferred temperature
of ~team is broadly from about 410F to about 540F;
when the oil is within the preferred temperature range
of from about 460F to about 490F, the preferred steam
temperature ranges fxom about 440F to about 510F.
, :
2n Throughout this specification reference is made to
steam as the deodorization agent. Steam is highly pre-
ferred for this purpose as it is readily a~ailable in
high purity and because it does not injure the oils being
deodorized. Other deodorization agents can be used,
however, ~or example, gases which are inert under the
conditions of the process, such as nitrogen or hydrogen.
` Oxygen and air are unsuitable, however, as they would
cause oxidation and degradation of the oils being
deodoriæed.
The deodorization chamber per se and its COmpQnents
can be any type of packed vapor-liquid contacting cham-
ber, such as those which are well known in the chemical
;~ en~ineering art. See, for example, R. H. Perry et al,
eds., Chemical Engineers' Handbook (McGraw-Hill, 4th ed.,
1963), p-. 18-25 to 18~53; J. S. Ec~ert et al, Chemical
Engineering Progress 54, No. 1, 70-75 tJanuary 1958~,
57, No. 9, 54-58 (September 1961), 59, No. S, 76-82
; (May 1963), and 62, No. 1, 59-67 ~January 1966); and
K. E. Porter, Chemistry and Industrv 182~89 (Eeb. ~,
-
~ 1 72~55
: 1967). These references also describe various kinds of
packing materials which can be used.
The edible oils which can be deodorized by the
process of this invention include various substances of
plant or animal origin which consist predominantly of
glyceryl esters of fatty acids, e.g. triglycerides, in-
cluding both those commonly called "oils" which are
: liquid at atmospheric pressure and room temperature, andthose commonly called "~ats" which are solid or semi-
solid under these conditions, but liquid at the tempera-
ture of heat-bleaching and deodorization (i.e. about
350F to 520F). Preferred oils are tallow, lard, and
the common ~dible vegetable oils used for the production
: : of salad oil and shortenings, e.g. cottonseed, peanut,
safflower, palm, soybean, rapeseed, sunflower, corn, and
coconut oils. The invention is particularly applicable
; to the heat efficient deodorization of sunflower seed
oil.
The selectlon:of a pumpable bland flavor-stable
:; 20 processing temperature~within the range of about 480F
: to about 340F is interdependent on the type of edible
oil belng processed and the dormant oil times of the
~:~z~ deodorization system being used.
Preferably, the bland flavor-stable outgoing oil
: : :: 25 is pumped at a temperature above about 340F for heat
recovary via heat interchanger means.
The improved process of this invention
is designed for utilizing heat and recovering energy in
hot, freshly deodorized outgoing oil in a deodorization
system wherein the hot deodorized outgoing oil is
utilized to warm up cold undeodorized incoming oil via
:~ a heat interchanger means, said process comprising the
: steps of:
(a) deodorizing said incoming oil at a temperature
of about 425F to about 520F to provide said hot,
freshly deodorized oil having a temperature above a hot
, ~
:
:
~ 1 ~26~
pumpable ougoing oil bland flavor~stable processing
temperature;
(b) utilizing a cooling means to quench said hot,
freshly deodorized outgoing oil to said hot, pumpable
outgoing oil bland flavor-stable processing temperature
of ~rom about 480F to about 340~; and
(c) passing said hot, pumpable outgoing oil
through said heat interchanger means to warm up said
cold undeodorized incoming oil.
Industrial Applicatlon
The method of this invention is useful in all types
of deodorization processes which can be modified to:
(1) quench the emperature of the hot, freshly deodor-
ized oil to a bland oil fla~or-stable temperature before
pumping the hot oil through a heat interchanger to warm
up cold incoming oil. Thus, it will be clear to those
skilled in the art that an important principle of this
invention is that hot, freshly deodorized oil must be
quenched to its bland flavor-stable temperature before
O it can be held dormant for further processing.
The term "dormant oil" is defined herein as hot
;~ deodorized oil, held in a tray or reservoir as a pool
without sparging or significant steam stripping or
simply oil that is being pumped. Dormant oil can be
oil that dwells in an oil-sealed reservoir. Dormant
oil can be oil pumped through a l-ine or heat inter-
; changer. Dormant dèodorized oil held beyond its crit-
ical dormant time at a temperature above its bland
flavor-stable temperature, will degrade. The term
"dormant time" as used herein technically refers to the
time freshly deodorized oil dwells in a deodorization
process that is no longer being sparged or stripped.
The term ~Ipumpable bland flavor-stable processing
temperature of a deodorized oil" refers herein to a
temperature or temperature range at which hot deodorized
oil can be held "dormant'l or pumped without loss of its
bland flavor. There is a maximum pumpable bland flavor-
stable processing temperature for each particular oil
and each oil has a unique dormant process time-
~ 17~BS5
temperature interdependency wherein said dormantpxocess time increases as the temperature decreases.
The term "~uenched oil" as used herein refers to hot,
freshly deodorized oil that has been cooled to its
PBFSPT. The term "quench time" is that time re~uired
to reduce the temperature for the deodorization temp-
erature to the PBFSPT. There is a critical quench time
for each particular oil and each oil has a unique
critical process quench time - PBFSP temperature inter-
dependency wherein said critical quench ~rocess timeincreases as the hot deodorization temperature decreases.
Therefore, the specific process or system used is
also a factor in selecting times and temperatures since
the equipment limitations will determine the requisite
time that the oil is held "dormant" at various processing
temperatures. Hot oil selectively quenched to its maximum
bland flavor-stable processing temperature can be safely
~ ~imped through heat inter~hangers which utilize the heat
of the hot outgoing oil to warm up rold incoming oil.
The incoming oil of this invention is refined and
bleached oil or oil which has b~en processed with one or
more of the following processes: refined, bleached,
hydxogenated, winterized, dewaxed, interesterified, etc.
For a more detailed disclosure of the types of
refined and processed oils useful as incoming oil for
the present invention, the reader is referred to
U.S. Patent 4,035,402, Levine, dated July 12, 1977
Steam-vacuum deodorization is preferred. The
process consists o~ steam stripping or steam distilling
of the volatile odori~erous constituents at elevated
temperature and reduced pressure.
,
:
$ 5
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~ he most common shape of the batch deodorizer is
a cylindrical vessel two to four ,imes as high as it
is wide. Provision is made to heat the oil internally
or externally by steam, direct firing, or "Dowtherm"TM
S vapor. "Dowtherm" is a eutectic mixture of diphenyl
and diphenyl oxide which is reportedly more suitable
than steam because of the high temperature range that
is required for deodorization. The vacuum equipment
consists of multistage steam ejectors with barometric
condensers. Stripping steam is introduced at the bottom
by means of spiders or orifice plates. Good steam dis-
tribution is essential, as it provides the additional
advantage of effective agitation. The classical batch
deodorization cycle usually is from 4 to 8 hours.
lS Batch deodorization systems can be modified to recover
the heat of the hot, deodorized oil by determining the
oil's bland, flavor-stable temperature and quenching
the oil to that temperature with a cooling means. The
` hot quenched deodorized oil can then be safely pumped
to heat cooler incoming oil. Some sparging of the hot,
deodorized oil for agitation is preferred.
A semi-continuous system designed by the Girdler
Corporation has found laxge-scale application. It
consists essentially of~a large cylindrical vessel
contai~ing five pans. A motor-operated timing device
opens and closes valves automatically. They regulate
the flow of product from the higher to the next lower
pan. The oil is preheated and de-aerated in the top pan.
In the second pan the temperature of the charge is in-
; 30 creased to about 240C. Deodorization is mainly carried
out in the third and fourth pans. In the last pan the
temperature is reduced by water cooling while the product
continues to be steam stripped under vacuum. The total
operating time is about 2-1/2 hours. In a modified
system, heat recovery can be accomplished by determining
the bland, flavor-stable processing temperature of the
oil and following the guidelines set out herein.
1~ t
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! 1 72655
Several continuous deodorizers also are widely
used. The system manufactured by Foster Wheeler Cor-
poxation consists essentially o a vertical stainless
steel column provided with trays and bubble caps. The
oil, cascading from top to bottom, moves counter-
currently to the ascending steam. U.S. Patent 3,542,653,
Lowrey et al, Nov. 24, 1970, relates to an apparatus
and process for continuous heat-bleaching and high
temperature steam deodorization of edible oils.
As stated above, in some processes some steam
stripping of the "dormant" hot deodorized oil is pre-
ferred durin~ the quenching step for agitation while the
hot oil is dwelling prior to being pumped. It provides
agitation and also assures the maintenance of optimum
bland oil flavor in some systems. Less s eam is needed
for this agitation than i~ required for deodorization.
This invention is mainly described hexein in the
context of a continuous deodorization process. However,
will be apparent to those skilled in the art, in the
light of this disclosure, that the principles of this
invention are equally applicable to modified batch and
semi-continuous deodoxization processes which are modified
to utilize the heat of the outgoing hot deodorized oil to
~ ~ save energy. The hot deodorized oil in a modified system
; must be quenched if it is to be momentarily held dormant,
e.g. as a pool in a vacuum oil-sealed reservoir means
prior to pumping it to heat interchangers.
The Figure shows a deodorizing unit 1 having a hot
incoming oil feed inlet 2. The deodorixation unit 1
comprises packing 3 supported on a screen means 3a,
which are standard items in the art. The hot incoming
oil 2 is treated with super-heated stripping steam 20
in the upper cham~er 22 inside the unit 1 to sparge and
strip out odor-forming matter from the oil. The unit 1
also has a separate lower cooling reser~oir 5 containing
a pool of dormant hot deodorized outgoing oil 6. The
reservoir 5 receives a steady stream of hot, freshly
deodorized oil 21 falling from the upper chamber 22
~ 172BS5
-12-
of the unit 1. There the hot, freshly deodorized oil 21
is cooled to a bland flavor-stable processing tempera~ure
by the quenching oil 23 in the lower reservoir 5 before
it is pumped through the heat interchanger means 24
wherein cold incoming oil 25 is warmed by the hot quenched
deodori2ed oil 6 before said incoming oil 25 is finally
heated with a high tempPrature heating means 26. The
hot quenched deodorized oil is finally cooled to 120F-
140F by a cooler means 27 which is preferably a water
cooler The means 24, 26 and 27 pxeferably comprise a
battery of heaters or heat interchangers.
For a detailed disclosure of deodorization systems
in general, pac~ing, bubble caps, residence times, etc.
~ which are not inconsistent with this invention, reference
;~ 15 is made to U.S. Patent 3,542,653, of Lowrey et al,
dated November 24, 197Q~
The figure illustrates a system whereby heat is
recovered and the bland flavor of the deodorized oil is
maintained. The quenched deodorized oil 6 after passing
~ 20 through the heat interchanger means 24 is further cooled
:~ ~ia cooler 27 to a packing (storage) safe temperature of
about 120F to 140F, which cooled oil 23 can also be
used as ~uenching oil 23.
.The continuous deodorization unit quench, "CDU
quench" method is a preferred embodiment of this invention.
~: The preferred method comprises showering recycled cooled
deodorized quenchiny oil 23 through a quenching means 28
onto a pool of quenched deodorized oil 6 in the cooling
~ reservoir 5 to quench and agitate the hot, freshly deod-
~ 30 ori~ed oil 21 as it drops into said oil pool 6. The hot,
;~ freshly processed deodorizPd oil 21 is rapidly quenched
to a bland flavor stable processing temperature oil
wit.hin a fraction of a second. Additional agitation of
~ the quenched oil 6 can be provided by stripping steam 20a
:~ 35 or water ~imply injected into the pool of oil. An alter-
native quenching means for cooling the hot, freshly
deodorized oil comprises injecting the quenching oil
directly into the oil pool 6.
::
~ î726~
As stated earlier, the preferred pumpable bland
flavor-stable temperature of a particular oil varies
from oil to oil and rom system to system. The maximum
temperature at which hot deodorized oil can be pumped
to recover heat in a deodorization process while the
bland flavor of the freshly deodorized oil is maintained,
is pxeferred. The preferred bland flavor-stable temp-
erature, from an ener~y efficient standpoint, is the
maxim~m temperature of the hot deodorized outgoing oil
at which the bland oil flavor is maintained in a heat
recovery step. In a preferred embodiment the maximum
- heat of the hot deodorized oil is used in a heat inter-
changer means to save energy.
An alternative to a direct oil-to-oil quench is
submerged internal heat e~changer coils which are used
~ to ~uench the hot, freshly processed deodorized oil in
;` reservoirs like reservoir 5, shown in the Figure. Such
types of heat exchangers must cool the hot oil down to
its bland flavor-stable processing temperature fast
enough to maintain optimum good taste and bland flavor
in deodorized oil, i.e. within the critical quench time.
Alternate methods and equipment for quenching hot,
freshly deodorized oiI to bland flavor stable temperature,
other than an oil-sealed lower cooling reservoir like 5
~;~ 25 are contemplated as within the scope of this invention.
Typical examples of such devices are found in: "Deod-
orization 1975", C~ T. Zehnder, Journal of American Oil
- Chemists' Socie~y, June 1976 (Vol. 53), and Gavin et al,
J. Am. Oil Chemlsts' Society, ~Jovember 1973, pp. 46~A-
477A (Vol. 50).
.
It was surprisingly discovered that hot, freshly
deodorized oils having too hi~h a temperature to be
safely pumped could be quenched to a slightly lower but
3s bland fla~or-stable temperature to avoid flavor degrada-
tion before pumping. Sunflower seed oil is a very
difficult oil to deodorize. It is preferably
deodorized at a high temperature of about 490F to
about 460F in a continuous deodorizer. The
freshly deodori~ed sunflower seed oil must
.,, ~ . i
~ ~ 72~5
-14-
be quenched in a CDU to its flavor process stable
temperature of about 445F to about 410F within a
quench time of about a fraction of a second to within
about S0 seconds.
Again, it has been discovered that hot, freshly
processed deodori~ed oil which has optimum good taste
(a bland flavor) will degrade ~ L if held dormant
at too high a temperature without sparging (stripping)
under vacuum. Hot, freshly deodorized sunflower seed
oil at high deodorization temperatures held dormant for
just a few seconds can show degradation. It was surpris-
ingly discovered that hot quenched deodorized sunflower
- seed outgoing oil having a temperature below about 445F
i~ a CDU, as illustrated, maintains its optimum good
taste and bland flavors, but unquenched freshly deodor-
ized outgoing sunflower seed oil shows degradation when
held dormant. Short dormant (dwell) times, e.g. about
60 seconds and less, in a continuous pool in a reservoir
like reservoir 5 and associated piping to cooler 24 of
a CDU at high deodorization temperatures is enough to
significantly degrade the oil, if not quenched. Similar
degradation would happen in modified batch and semi-
continuous processes so designed to recover the maximum
heat of the freshly deodorized oil.
In a CDU system, as shown in the ~igure, sunflower
seed oil can be deodorized at a temperature of fro~
about 446F to about 510F, and preferably 460F to 490F.
The hot, freshly deodorized outgoing oil 21 dribbles
out of the upper chamber 22 down into the lower reservoir.
Thus, hot, freshly deodorized outgoing oil 21 is quenched
in resexvoir 5 with ~uenching oil 23 to a temperature
; of below about 445F, its bland flavor-stable temperature.
It is preferably quenched to a temperature of about 410F
+ 5F within a quench time of about a fraction o a second
The hot~ freshly deodorized oil i preferably
quenched by mixing it with 120-140F prior deodorized
quenching oil 23. This step in a CDU is preferably ac-
complished by spraying a shower o~ the quenching oil 23
into the lower reservoir 5 of a CDU system whereby the
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~ 1 72655
-15-
hot and cooled oils are contacted, mixed and a~itated.
j The quenched deodorized outgoing oil 6 in the
, reservoir 5 can then be safely pumped out for further
cooling, e.g. via a heat interchanger cooler 24 and then
further cooled via cooler 27 to a packing or storage
~ stable temperature of about 130F ~ 10F. The oil is
j then pumped to a storage tank, packed or recirculated
' to the cooling reservoir S as cool quenching oil 23.
eat interchanger cooler 24 is preferably designed
' 10 to also heat up incoming oil 25 and thereby save energy.
The ratio of quenching oil to hot, freshly
i deodorized oil, needed to quench to a bland flavor-
.f stable processing temperature, will vary depending on
the respective oil temperatures, dwell times and the
f 15 particular deodorization process being applied.
,
The bland flavor-stable processing temperature for
~;, a particular oil within a particular dwell time for a
particular system can be determined by trial and error.
The critical factor is to determine the pumpable bland
, 20 flavor-stable processing temperature (PBFSPT) of the oil
' being processed. One method of determining the PBFSPT
would be to withdraw a series of samples of hot,' freshly'
deodorized oil from a batch deodorization system at
decreasing temperatures and quenching them to various
25 temperatures at increasing times. Soybean oil, for
example, has a maximum PBFSPT of about 480F in a CDU
.f : ~ ~ , ' system as shown in the Figure. Soybean oil call
be deodorized at a temperature as high as 510F.
- Procedure to Determine the PBFSPT
The following describes a procedure used to
determine the PBFSP,T of deodorized oils. Equipment is
~' a 20 lb. capacity b'atch deodorizer under which is mounted
a small stainIess steel sample vessel connected by two
valves. The sample vessel is also vented up to the top
of the deodorizer via a valved vent linè. The procedure
~' for its operation is: inlet oil is charged into the
; dPodorizer and deodorized at desired temperature and
time to achieve a suitably bland flavor. Bland flavor
, ~ , .
:
} i726~
is verified by withdrawing an oil sample into the
sample vessel and immersing the sample vessel into an
ice bath while it is connected to the deodorizer and
opening the vent line to the top of the deodorizer to
equalize the pressures. Both valves connecting the sample
vessel with the deodorizer itsel are then opened, allow-
ing oil to freely drain from the deodorizer through the
two valves and into the sample vessel. Cooling of the
oil draining into the sample vessel is almost instan-
10 taneous, as its walls are essentially held at ice bath
conditions by the external ice bath. The sample of
deodorized oil thus withdrawn is then tasted by expert
oil evaluators to determine that it is suitably bland.
This sample is the flavor control. When testing, the
15 sample vessel is not precooled in an ice bath; but rather,
the sample is first withdrawn and, after withdrawal, the
sample vessel is cooled in an ice bath, which cooling is
; not commenced until a few seconds after sample withdrawal,
e.g. 2, 5, 10, 15 or 30 seconds or more. The tempera-
P 20 ture of the deodorized oil is reduced to various temp-
eratures to provide several different sampling temper-
atures. This process is repeated for several different
quenching times and several different sampling tempera-
tures to produce a map of flavor grades versus the con-
25 trol. This map o time and temperature allows one to
select the PBFSPT by giving the artisan an understanding
of the time at which the oil can be held at a specified
; temperature before it starts to degrade.
Examples 1-9
The specific conditions of Examples 1-9 are set out
in Table I. The equipment used is illustrated in the
Figure. Undeodorized, refined and bleached sunflower
seed incoming (inlet) oil was used for each run. Super-
heated stripping steam 20 was introduced at a rate of
about 0.5% by weight of the incoming oil 2. The steam
is introduced via steam inlet 20 below the screen 3a
level and is drawn through the upper chamber 22 via
~ vacuum source 30.
:~:
':
~ 17~B55
-17-
As shown in the Figure, some additional sparging
steam 20a can be introduced below the surface of the pool
of quenched oil 6 in the reservoir 5 for agitation and
good measure. Column operating pressures of about 5 mm
of mercury absolute pressure maximum were maintained at
the top of the column with a maximum operating pressure
differential (~ P) across the column of about 24 mm of
mercury. Preferably, a ~P of about 15 mm of mercury
are maintained. A ~ P of about 30 mm of mercury is not
too high. Results of several runs under various condi-
tions are shown in Table I.
The temperature of the hot incoming oil 2 approxi-
mates the temperature o~ the hot, freshly deodorized oil
21 in each run. The residence time of oil in the upper
chamber 22 of the unit is about a minute and the residence
time of t~le oil in reservoir 5 plus pumping time to
interchanger 24 of the unit is about 1 to 2 minutes.
, ~ _
The ratios of the quenching oil to hot, freshly
deodorized oil fed into the system were adjusted to
achieve the desired pool temperature shown in the
Table.
The pool temperatures of Examples 2, 3, 4, 7, 8 and
9 illustrate some~preferred PSFSPTs of this invention.
TABLE_I
Run Incoming Oil Quench Oil Pool
Temperature Temperature Temperature DOF
1 484F No Quench (480F) 7.1
2 465F 130F 440F 8.0
3 465F 130F 410F 8.0
~-~ 30 4 484F 120F 405F 7.6
S 468F No Quench* (460F)* 7.3
6 480F No Quench* (480F)* 7.3
7 484F 120F* 445F* 7.8
8 460F 120F* 410F* 7.7
9 486F 120F* 410F* 7.7
* Pool sparge with steam
' ;
.
~ 1 72~55
-18-
Deodorized oil flavor (DOF) is subjectively evalu
ated on a 10:1 grading scale with 10 being a bland oil
and l having a very objectionable or strong off-flavor.
A 0.2 flavor differential is significant. As can be
seen, oils deodorized without the aid of the quench
system of this invention graded lower in flavor quality
than all the oils deodorized using the quench system of
this invention.
Compare unquenched run l with quenched run 4. They
respectively had deodorized oil flavors of 7.1 and 7.6.
Both were dormant in the oil pool 6 and were pumped
dormant at temperatures of 480F and 405F, respectively.
Also compare the flavors of unquenched sparged pool oil
run 6 pumped at 480F with quenched, sparged pool oil
run 7 pumpad at 445F which were respectively 7.3 and
7.8.
The hot, freshly deodorized oils of runs 2, 3, 4,
~`~` 7, 8 and 9 were quenched to their PBFSP temperatures
within 50 seconds and probably within 10 seconds. ~he
residence or dwell times in the pool 6 of reservoir 5
were each about 1-2 minutes.
~;~ Comparing run l, unquenched and dormant oil, with
,,
runs 5 and 6, unquenched and steam sparged oils, gives
; ~ a direct comparison of the effect of steam sparging on
oil quality. These runs had deodorized oil flavors of
7.1, 7.3 and 7.3 respectively. This comparison shows
that steam sparging is directionally preferred and does
improve flavor. This improvement, however, is over-
shadowed by the greater flavor improvement achieved via
quenching. Steam sparging is directionally better but
~; ~ optional.
In all of the runs (1-9) pool oil 6 was pumped to
heat exchanger 24 whereby the cooler inlet oil 5 was
warmed to save energy. Less energy was required to heat
the inlet oil via high temperature heater means 26 to
the desired inlet deodori ation temperature.
,~
