Download Food Thermalization and Moisturization Culinology

Culinology: Food Thermoisturization
1 C. 5/8/2017 Winston L. Shelton, D.A.B. (Hon.)
Study, Lecture & Experiment Series
Food Thermalization and Moisturization Culinology
through
Controlled Vapor Technology
By Winston L. Shelton, D. A. B.
(Hon.)
This workbook represents an educational program on the fundamentals of heating and controlling the
moisture content in foods. It defines and explains Shelton’s Three Laws for Thermoisturization of Foods
and provides simple experiments that gives the culinarian a solid foundation in its science. It is divided
into material for study, study-lecture, experimentation, and testing.
The technology describes the control of food temperature and food moisture through the control of the
temperature and the amount of water vapor in the air surrounding the food. It is referred to commercially
as Controlled Vapor Technology.
The first purpose of this material is to give the culinarian an understanding of the fundamentals of food
thermalizing and moisturizing. Because of its technical correctness, it is expected that all manufacturers
will someday utilize it in the design of their equipment to make it universally available. One important
objective is to assist the culinarian in the selection of equipment.
A glossary of terms is provided that reflects the specific meaning of some of the words used in the
workbook. Conversion charts are provided yielding Relative Humidity from Dry and Wet Bulb
temperatures; Water Vapor Pressure from Water Temperature, and Fahrenheit temperatures from
Celsius temperatures and reverse.
A supplemental Power Point presentation is available (with notes) for the student Culinarian that provides
a simplified explanation of the principle. It is recommended that this presentation be made as an
introduction to the subject. Thirty minutes viewing time is recommended.
The Experiment series is a teaching in the fundamental principles involved and a demonstration of the
superior benefits of the technology in holding and cooking applications. Two of the experiments can be
conducted with simple utensils found in most kitchens. The last three require a Controlled Vapor
Technology Holding Cabinet and a Roasting Oven.
Culinology: Food Thermoisturization
Food Thermoisturization
through Technology
Over the centuries, culinarians have
developed techniques to make use of and
preserve the moisture in foods. En papillote,
covering with foil, casseroles, ‘roasting
pans’, ‘clam baking’, etc. use vaporized food
moisture to prepare foods. Others make use
of hot or boiling water in cooking. These are
referred to as ‘moist heat method’ of food
preparation. Bake, toast, and the like have
been regarded as ‘dry heat method’ of food
preparation. The reality is that most of the
techniques are combinations of both
because of the ever-present contribution of
evaporated food moisture to the process.
Whatever the process, it has taken high skill
and close attention by the chef to produce
high quality foods.
Various culinary techniques were studied to
determine the factors controlling food
temperature and food moisture. Experiments
were conducted to investigate the correlation
of food temperature and food moisture with
the two components of relative humidity; i.e.,
air dry bulb temperature and air wet bulb
temperature. The results established a
consistent correlation of the two factors with
food temperature and food moisture.
The work of other scientists was investigated
to determine the extent of agreement (or
disagreement) with the findings (see
Bibliography). The first three references of
the bibliography had a different and more
limited objective from the work reported
here, however the findings were in
agreement with this work. The last two
references of the bibliography represented
text material and a handbook that were in
agreement also with these findings. There
were no disagreements in any of the
referenced work with the conclusions
reported here.
Because of the general relationships
developed over years of testing and because
of the agreement with other investigators
without disagreement, the correlations are
presented here as the following Physical
Laws:
2 C. 5/8/2017 Winston L. Shelton, D.A.B. (Hon.)
Shelton’s Three Laws of Food
Thermoisturization
1. “When heat transfer is by convection
only, foods with free moisture come
to a temperature equilibrium with the
wet bulb temperature of the air
stream.”
2. “When heat transfer is by convection
only, foods with bound moisture
come to a temperature equilibrium
greater than the wet bulb temperature
and less than the dry bulb
temperature of the air stream.”
3. “When heat transfer is by convection
only, foods with free moisture have
an evaporation rate that is dependent
upon the difference between the dry
bulb temperature of the air stream
and the surface temperature of the
foods.”
As is frequently the case with the
development of new technologies, new
terms or words are needed. Culinarians
have been conditioned to use terms such as
proofing, holding, warming, braising,
poaching, steaming, etc. to refer to particular
techniques, equipment types and resulting
food qualities. The scientific world prefers to
use ‘thermalizing’ to represent the heat
transfer phenomena in each of the
processes. In this text, the term
‘thermoisturization’ is coined to represent
simultaneous thermalization and
moisturization of foods. The technology
establishes the importance of utilizing two
different quality heat sources to cause it to
be a dry convection oven at one end of the
scale and a steamer at the other end. In
reality, it is degrees of wet and dry that are of
greater importance to the culinarian.
Food, a Wet Body Science
The First, Second, and Third Laws of
Thermoisturization provide understanding of
the control of food quality utilizing two heat
sources. The laws state how food
temperature and food moisture can be
controlled through control of the wet and dry
bulb temperatures of the food atmosphere.
Culinology: Food Thermoisturization
Figure 1
Moisture Content
of Common Raw Foods
3 C. 5/8/2017 Winston L. Shelton, D.A.B. (Hon.)
relative humidity down into its components to
control the food qualities in which the
culinarian is interested.
Defining Wet Bulb Temperature
Food
Lean Beef
Fish
Veal
Fowl
Asparagus
Spinach
Onions
Peaches
Apples
% Water
75
82
77
76
93
90
86
85
84
‘Wet and Dry Bulb Temperature’ terms are
used as part of the science of weather,
climate, environment, etc. The meteorologist
converts the terms into ‘relative humidity’ to
represent their combined meaning. It is the
preferred measure that the meteorologist
uses to describe the amount of water vapor
in the atmosphere. One has been
conditioned to understand that a ‘muggy’
atmosphere represents high relative
humidity and that low relative humidity is
characteristic of a ‘dry’ atmosphere.
As a wetted thermometer bulb is placed in
an air stream having a 70F temperature,
evaporation of the water begins from the
wetted thermometer bulb. Evaporation is a
cooling process and as moisture is
evaporated from the wet sensing bulb of the
thermometer, it indicates temperatures of
lower and lower values than the air (dry bulb)
temperature. Finally, the wet bulb
thermometer reading remains constant—
indicating a balance between the heating
effect of the higher air temperature and the
cooling effect of continuing evaporation.
The reading is referred to as the wet bulb
temperature of the air
In the above example, evaporation and
cooling of the water on the wetted
thermometer bulb continues until 60F (for
example) is reached. When cooling stops, a
condition of 60F is therefore identified as
the wet bulb temperature. (A chart can now
be entered with the 70F dry bulb
temperature and the 60F wet bulb
temperature to determine that the relative
humidity is 55%).
In order for the thermometer to be
considered a wet bulb thermometer, it is
necessary for the sensing bulb of the
thermometer to be ‘wet’. Since wetting must
be maintained while moisture is being
evaporated, the sensing bulb is normally
fitted with a woven cotton gauze tube to
serve as a wick. The purpose of the gauze
is to provide a reservoir of moisture to
maintain wetness even though the total
supply of moisture is being depleted by
evaporation. In some cases, a lower portion
of the wick is inserted into a small vessel
containing water.
Figure 2: Relative Humidity is
determined from Wet and Dry Bulb
Temperatures.
The three laws of food thermoisturization
deal with the two components of relative
humidity rather than relative humidity itself.
In other words, it was necessary to break
Free Moisture Foods and the First
Law of Food Thermoisturization
In the above section, it was required that the
sensing bulb of the thermometer has an
external surface that is wet. Fresh meats,
sliced vegetables, and sliced fruits meet that
requirement. Because of their structure, after
slicing, the internal moisture can migrate to
the cut surfaces to keep those surfaces wet
Culinology: Food Thermoisturization
until most of their moisture is depleted.
These are defined as free moisture foods.
Free moisture foods therefore behave like
the wetted gauze wick placed on the
thermometer bulb and acquire wet bulb
temperature also, with one exception: as the
mass of the food becomes larger and larger,
it takes longer and longer time for the food
mass to reach wet bulb temperature. But it
makes no difference whether the foods are
placed in the atmosphere at a higher
temperature or lower temperature than the
wet bulb temperature, nor to their mass, they
will finally stabilize at the temperature
measured by a simple wetted thermometer
bulb.
This is the example of the First Law of
Thermoisturization.
Dry Bulb
Evaporation
Temperature
Temp.
Food
Temp.
Wet Bulb
Temp.
Potato
Slice
Figure 3: Wetness of cut foods
produces the same effect as the
wet gauze.
Practically all uncooked foods are regarded
as free moisture foods. If the cooked food is
to be regarded as fresh and succulent, the
cooking process should remove only a small
amount of the total moisture. As it is
traditional to brown meats; to crust breads;
or to provide external dryness to finger
foods; it has become desirable to void the
external surfaces of moisture while
maintaining as much internal moisture as
possible. These foods therefore may have
free moisture internally and bound moisture
externally.
Heating Foods
4 C. 5/8/2017 Winston L. Shelton, D.A.B. (Hon.)
As refrigerated foods are placed in an air
stream, using the atmospheric example
above, heat from two different atmospheric
sources begin to raise its temperature. The
first heat source is the one most easily
understood: It is the heat in the dry air that
attempts to raise the temperature of the
foods.
The second is least understood but most
important: It is the heat in the vapor
(represented by the air wet bulb
temperature) that condenses onto the food
to give up its heat thus to raise the
temperature of the foods. Condensation
continues until the food has reached 60F,
the wet bulb temperature of the air stream.
Just as evaporation is a powerful cooling
process, condensation is a powerful heating
process for the object on which
condensation takes place. When the food
temperature reaches 60F, condensation
discontinues; however the difference
between the dry bulb temperature and the
food temperature is 10F (in our example),
so heat continues to flow from the 70F air to
the food.
The effect of this heat flow however is not
the continuation of the march of food
temperature to the 70F temperature of the
dry air. The very high heat of vaporization of
moisture from the food into the dry air
prevents it, and the food temperature will
remain at a temperature as measured by a
wetted thermometer bulb in the air stream.
The effect of the heat flow from the dry air
therefore is to evaporate moisture.
While the examples utilize an air stream
having human comfort like conditions of wet
and dry bulb temperatures, the laws apply
throughout the freezing to boiling range of
water temperatures. The laws therefore
apply to refrigeration as well as cooking
applications involving forced and free gravity
convection.
While there are many exceptions to the ideal
conditions required of the food and of the
heat delivery system to meet the First Law of
Food Thermoisturization, nevertheless it
provides a sound basis for understanding
the phenomena of cooking.
Culinology: Food Thermoisturization
Bound Moisture Foods and the
Second Law of Thermoisturization
As the food referenced above remains in the
60F wet bulb temperature/70F dry bulb
temperature air stream, the moisture
continues to migrate to the surface and
evaporate. As all free moisture evaporates,
the only remaining moisture is tied up in the
individual cells of the food. The remaining
cell moisture is identified as bound moisture.
As the free moisture becomes less available,
the food surface can now be thought of as
partially wet and partially dry.
The part that is wet obeys the first law while
the part that is dry tends to become the dry
bulb temperature; thus the resultant food
temperature is a weighted average of the
two effects, higher than wet bulb
temperature but less than dry bulb
temperature.
This is the example of the Second Law of
Food Thermoisturization.
This is the realm of crackers, nuts, jerky,
and other dry foods. It also identifies foods
that have dried to the point they are no
longer regarded as edible.
The skin of fruits and vegetables is
substantially impervious to moisture flow. In
an unpeeled condition, they could be
regarded as having only bound moisture. As
the skin is removed, or the fruit or vegetable
is sliced, they behave as free moisture
foods.
Evaporation of Moisture and the
Third Law of Food
Thermoisturization
The Third Law of Thermoisturization states
“When heat transfer is by convection only,
foods with free moisture have an
evaporation rate that is dependent upon the
difference between the dry bulb temperature
of the air stream and the surface
temperature of the foods.”
Earlier we learned, under the assumptions of
convective heat transfer and free moisture
foods, that food temperature becomes wet
bulb temperature. Therefore, substituting
“…wet bulb temperature…” for “surface
temperature of the foods” in the Third Law,
one would conclude that the evaporation
rate is dependent upon “…the difference
5 C. 5/8/2017 Winston L. Shelton, D.A.B. (Hon.)
between the dry bulb temperature and the
wet bulb temperature of the air stream” after
the temperature of the food surface has
stabilized. The reader is reminded that there
can be no evaporation of food moisture until
the food surface has reached wet bulb
temperature.
This is explained using the wetted wick of
the wet bulb thermometer as an example: If
one were to lower the air dry bulb
temperature below 70F to approach the
60F value of the wet bulb thermometer, less
and less heat is delivered to the wet wick.
Finally, as the air dry bulb temperature
reaches 60F, no heat is delivered to the wet
wick and no evaporation can take place.
(The principle of the Conservation of Energy
states that “…If a body is isolated….so that it
neither receives nor gives out energy, its
total store of energy… remains constant.”)
Simply stated-if there is no input there can
be no output.
We can use the example of the wetted wick
of the thermometer as the equivalent for
food under the assumptions of convective
heat and free moisture foods, to state that
evaporation is zero when the dry and wet
bulb temperatures are identical; and that
evaporation increases as wet and dry bulb
differences increase.
This is the example of the Third Law of
Thermoisturization.
Equipment Design
The significance of the correlation of food
temperature with wet bulb temperature is
realized through equipment design that has
the ability to cook food to a selected
doneness temperature and hold those foods
for hours without burning or overcooking.
Doneness temperatures are substantially
below 212F. Few people can put foods
hotter than 150F in their mouth. Yet
traditional cooking equipment cooks at
temperatures of up to 600F; requiring a
high degree of attention by the culinarian to
produce foods that are cooked to the desired
doneness without overcooking. If one is to
control food temperature within a few
degrees, it must be done with a very
considerable amount of attention and
frequent inspection. When doneness is
reached using traditional single control
equipment, the foods must be removed
Culinology: Food Thermoisturization
6 C. 5/8/2017 Winston L. Shelton, D.A.B. (Hon.)
promptly to avoid overcooking, drying, and
burning.
On the other hand, ovens having wet bulb
temperature control can have their wet bulb
temperature set at 135F (for example) and
cook prime rib to 135F without any concern
for overcooking. With the dry bulb control
set at 145F, the driving force to evaporate
moisture is only 10F. In this type of
equipment environment, the prime rib can be
held for hours without any significant change
in quality.
Temperature and Moisture Control
Equipment
The above descriptions demonstrate the Three
Laws of Thermoisturization. It describes how
hot foods cool to wet bulb temperature through
evaporation and how cold foods are heated to
wet bulb temperature through condensation. It
follows that food temperature can be controlled
through the control of wet bulb temperature.
The examples also describe the relationship of
food moisture evaporation from the drying
force produced by the difference between the
dry bulb and wet bulb temperatures.
This principle is utilized in thermoisturization
equipment to control food temperature and
to limit food moisture evaporation. While
the easiest example to understand may be
its utilization in hot food holding equipment, it
provides superior benefits in proofing,
steaming, and cooking applications where
convection is the primary mode of heat
transfer.
To control wet bulb temperature of the food
environment, a water vessel is made a part
of the food chamber and fitted with a heater
and temperature control system. The
temperature of the water establishes the wet
bulb temperature.
With the addition of an air heater and
temperature control system, the air can be
heated to temperatures greater than the wet
bulb temperature. When they are equal,
there is no evaporation, but as the air
temperature exceeds the wet bulb,
evaporation takes place. As the difference
increases, so also does the evaporation rate.
The higher the difference, the greater is the
evaporation rate; however, the food
temperature of free moisture foods remains
primarily fixed to the wet bulb temperature.
Figure 4: Equipment controls Wet and Dry
Bulb Temperatures thus Food Temperature
and Food Moisture.
Another important consideration is
characteristic of thermoisturization
technology cooking equipment. As food is
placed in an oven having only a dry heat
source, the dry heat source begins to
evaporate food moisture. Since evaporation
of moisture demands that the Heat of
Vaporization be supplied, much of the heat
applied to the foods counterproductively
evaporates moisture instead of raising the
temperature of foods. Thus a doublebarreled fault exists—cooking is slowed and
food moisture is wasted. Thermoisturization
technology equipment prevents evaporation
until the food temperature reaches wet bulb
temperature as all the heat is utilized to raise
the temperature of the foods without loss of
precious food moisture.
The Importance of Control Design
The Three Laws of Food Thermoisturization
places special importance on the selection
of equipment that control food temperature
without having any effect on moisture and
control moisture without having any effect
upon food temperature. Accomplishing this
cannot be done with independent
temperature controllers such as the common
thermostat. Food temperature is controlled
only by wet bulb temperature; however food
Culinology: Food Thermoisturization
moisture is dependent upon the difference
between the dry and wet bulb temperatures.
The solution is to utilize a controller that
controls wet bulb temperature to control food
temperature; and then control the difference
between the dry bulb temperature and wet
bulb to control moisture evaporation. In other
words, it is not the magnitude of the dry bulb
temperature alone that governs evaporation;
it is the relationship of the dry bulb to the wet
bulb temperature. This principle is satisfied
with ‘computer like’ controls.
Forced Convection Effect
The primary effect of air velocity is to sweep
moisture away from the foods to aid
evaporation of food moisture. While the
relationship of food moisture evaporation to
velocity of air over the food is not a part of
this study, the use of forced convection is
known to be useful to food preparation when
rapid browning of bakery goods is a
requirement, for example.
Notes:______________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
7 C. 5/8/2017 Winston L. Shelton, D.A.B. (Hon.)
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
___________________________________
Culinology: Food Thermoisturization
8
C. 01/15/03 Winston L. Shelton
Bibliography:
Cooking of Beef by Oven Roasting: A Study of Heat and Mass Transfer, N. E. Bengtsson, et al., Journal of
Food Science, Vol. 41, p1047, (1976)
Water Loss Rates and Temperature Profiles of Dry Cooked Bovine Muscle, E. W. Godsalve, et al.,
Journal of Food Science, Vol. 42, p. 1038, (1977)
Cooking of Beef by Oven Roasting: A Study of Heat and Mass Transfer, N. E. Bengtsson, et al., Journal of
Food Science, Vol. 41, p1047, (1976)
Fundamentals of Food Engineering, Third Edition, Stanley C. Charm Sc. D., Avi Publishing Company,
Westport, Connecticut, p299
Perry’s Chemical Engineer’s Handbook, Sixth Edition, by Robert H. Perry and Don Green, McGraw-Hill
Book Company; chapter on “Solids Drying and Gas-Solid Systems”
Culinology: Food Thermoisturization
9
C. 01/15/03 Winston L. Shelton
Food Thermoisturization Test
1. The science of the application of culinary knowledge is called _____________.
2. The term _______________ means simultaneous thermalizing and moisturizing.
3. Food thermoisturization is a (wet) (dry) body science.
4. T F
Air temperature control only equipment does not allow the Chef to control food
temperature while keeping evaporation constant (nor control evaporation while keeping food
temperature constant).
5. T F
The thermoisturization principle embodied in Controlled Vapor Technology equipment
applies to proofing cabinets, holding cabinets, convection ovens, and steamers.
6. T F
Wet Bulb Temperature is the temperature that free moisture foods become in open air
and in convection cabinets and ovens.
7. T
F
Free moisture foods have moisture that can move to the surface and evaporate.
Indicate by circle which of the following foods are Free (F) or Bound (B) Moisture Foods.
8.
F
B
Cut Vegetables
9.
F
B
Butchered Fresh meats
10.
F
B
Nuts
11.
F
B
Sliced or peeled Fruits
12.
F
B
Pastry
13. T F
The temperature of bound moisture foods falls in between the temperature of dry objects
and the temperature of free moisture foods.
14. The transfer of heat from the sun to the earth is a (convective) (conductive) (radiant) heat transfer
process.
15. The transfer of heat from a heat source to air to foods is a (convective) (conductive) (radiant) heat
transfer process.
16. Transfer of heat from the exterior to the interior of foods is a (convective) (conductive) (radiant)
heat transfer process.
17. Evaporation of Food Moisture (cannot) (can) take place if the Wet Bulb Temperature is the same as
the Dry Bulb Temperature.
18. T F
In CVT equipment, the evaporation rate of moisture increases from zero as the difference
between the Dry Bulb – Wet Bulb Temperature increases from zero.
19. Skillet frying is a (convective) (conductive) (radiant) heat transfer process.
20.
T F
Large differences between the Oven Dry Bulb and Wet Bulb Temperatures increases
crispness in food holding equipment and browning of meats in ovens.
Culinology: Food Thermoisturization
10
C. 01/15/03 Winston L. Shelton
Experiment 1: Wet Body Food Science
Background: As heat is applied to wet bodies (hair, clothes, etc.) part of the heat is utilized to raise the
temperature of the body while the balance evaporates moisture. Foods having free moisture experience
the same phenomena. Since both temperature and moisture are important to the quality of foods, it is
important to apply the heat in a well-defined way—to control both. This is thermoisturization. The purpose
of this experiment is to demonstrate that some foods behave identically to wet bodies in general.
Equipment Needed:
Thermometer
Food Needed:
¼ “ thick potato slice
Object: To establish that some foods may behave as wet bodies in the heat transfer process.
Procedure:
1. Measure and record the air temperature (off of a fan) of the classroom.
2. Wrap a piece of dry fabric around the sensing portion of the thermometer.
3. Wet the fabric with warm tap water. Place in the air stream of a fan.
4. Record temperatures immediately and every 5 minutes until temperatures have stablized.
5. Insert the sensing portion of the thermometer in the potato slice.
6. Place in the air stream of a fan.
7. Record temperatures immediately and every 5 minutes until temperatures have stabilized.
Summary:
1. From a psychrometric chart involving temperatures in the range of 60 to 80F, determine the relative
humidity of the room (from nearest 10F values). (Psychrometric charts for values typical of the
human atmosphere and for food processing equipment is provided with this text).
2. From Thermoisturization Culinology, what is the reason for the correlation of the temperature of the
wetted fabric of the wet bulb sensor vs. the temperature of the potato slice?
3. What is the expected food temperature for fresh foods placed in the air stream?
4. State the natural law that applies.
Turn in Summary
Culinology: Food Thermoisturization
11
C. 01/15/03 Winston L. Shelton
Experiment 2: Immersion vs. Vapor Cooking
Background: In theory, foods cooked above the water surface of a closed and insulated pot, cook at
the same rates as foods cooked immersed in the water. This principle is used in Controlled Vapor
Technology equipment to cook foods to a precise temperature at any temperature up to and including the
temperature of boiling water.
Equipment Needed:
Sauce pot with rack.
Food Needed:
Two (2) small potatoes.
Object: To establish that heated water in a closed vessel heats foods as rapidly above the water as in the
water.
Procedure:
1. Insert the rack in the saucepot and fill to a water level just below that of the rack.
2. Put one of the potatoes in the water.
3. Put the other potato on the rack.
4. Adjust the heat input to produce boiling.
5. After ½ hour of boiling, remove the potatoes and record their temperature.
6. Repeat 1-5 above with the heat input preset to provide water temperature in the range of 140 to
160F.
Summary:
1. What is the reason for the correlation of the temperature of the two potatoes?
2. State the physical law and equation that applies.
Turn in Summary
Culinology: Food Thermoisturization
12
C. 01/15/03 Winston L. Shelton
Experiment 3: Temperature Control Characteristics of CVT Equipment
Background: Thermoisturization Culinology describes the physical phenomena by which food
temperature and food moisture can be controlled during the proofing, holding or cooking process. This
experiment applies to the temperature control portion of that science.
Equipment Needed:
Controlled Vapor Technology Holding Cabinet, with Controls as follows:
1. Food Temperature = Wet Bulb Temperature
2. Food Texture Temperature = Dry Bulb – Wet Bulb Temperature
Temperature Measuring Equipment (preferably thermocouple)
Object: To demonstrate the extent to which food temperature is controlled by wet bulb temperature vs.
dry bulb temperature.
Procedure:
1. Attach thermocouple’s (TC’s):

To evaporator sensor.

To air intake of fan.
2. Fill CVT evaporator; connect to electrical power; set Wet Bulb Temperature at 100F; set Dry – Wet
Bulb Temperature at 0F; turn power switch to ON; allow CVT cabinet to warm up for one hour.
3. Place TC into center of 1/2 “ thick slices of potatoes laid on middle rack of cabinet.
4. Record potato slice temperature every 5 minutes until temperatures stabilize.
5. Increase Wet Bulb Temperature setting by 40F and record temperatures every 5 minutes until
temperatures have stabilized.
6. With Wet Bulb Temperature set at 140F, increase Dry – Wet Bulb Temperature by 40F and record
temperatures of potato slice every 5 minutes until temperatures have stabilized.
Summary:
1. How much did the potato slice temperature change when the wet bulb temperature was changed by
40F?
2. How much did the potato slice temperature change when the dry bulb temperature was increased
over the wet bulb temperature by 40F?
3. State the natural law that applies.
Turn in Summary
Culinology: Food Thermoisturization
13
C. 01/15/03 Winston L. Shelton
Experiment 4: Moisture Control Characteristics of CVT Equipment
Background: Thermoisturization Culinology describes the physical phenomena by which food
temperature and food moisture can be controlled during the proofing, holding or cooking process. This
experiment applies to the moisture control portion of that science.
Equipment needed:
Controlled Vapor Technology Holding Cabinet, with Controls as follows:
1. Food Temperature = Wet Bulb Temperature
2. Food Texture Temperature = Dry Bulb – Wet Bulb Temperature
Precision scale (precise to 1% at 5 lbs.)
Object: To demonstrate the extent to which food moisture is controlled by wet bulb temperature vs. dry
bulb temperature.
Procedure:
1. Fill CVT evaporator; connect to electrical power; set Wet Bulb Temperature at 140F; set Dry – Wet
Bulb Temperature at 0F; turn power switch to ON.
2. Allow CVT cabinet to warm up for one hour.
3. Slice approximately 5 lbs. of potatoes, ½” thick. Record weight of potato slices.
4. Place in pan on middle shelf of CVT cabinet.
5.
After being held overnight, remove potatoes and weigh.
6.
Calculate % Shrinkage
7. % Shrinkage = ((initial potato weight – final potato weight) / initial potato weight) x 100
8. Set Wet Bulb Temp = 140F, Dry – Wet Bulb Temp = 40F. Repeat Steps 2-6.
Summary:
1. How much shrinkage did you experience when the dry bulb temperature equaled the wet bulb
temperature?
2. How much shrinkage did you experience when the dry bulb temperature was greater than the wet bulb
temperature?
3. State the natural law that applies.
Turn in Summary
Culinology: Food Thermoisturization
14
C. 01/15/03 Winston L. Shelton
Experiment 5: Temperature Control Characteristics of CVT Equipment
Background: Thermoisturization Culinology describes the physical phenomena by which food
temperature and food moisture can be controlled during the proofing, holding or cooking process. This
experiment applies to the temperature and moisture control portion of that science.
Equipment needed:
CVT Roasting Oven with Controls as follows:
1. Food Temperature = Wet Bulb Temperature
2. Browning Scale (0-10) = Dry Bulb – Wet Bulb Temperature
Precision scale (precise to 1% at 5 lbs.)
Temperature Measurement Equipment
Food: Beef Cut: Inside Round.
Object: To demonstrate the extent to which food temperature and moisture is controlled by wet bulb and
dry bulb temperature.
Procedure:
1. Fill CVT evaporator; connect to electrical power; set Doneness Temperature (Wet Bulb Temperature)
at 135F; set Browning Scale (0-10) at 3 (Dry – Wet Bulb Temperature); turn power switch to ON.
2. Allow oven to warm up for half-hour.
3. Record weight of Inside Round.
4. Place meat on rack; load oven; and close door.
5. Allow to cook all night.
6. In morning, remove load and probe temperatures at middle of each end and in center. Record
Temperatures.
7. Weigh. Calculate % Shrinkage
% Shrinkage = (initial weight – final weight) / initial weight) x 100
8. Slice at each end and in center. Comment on quality of cut, moisture level, and uniformity of cook.
Summary:
1. What was the variation of measured temperatures with Doneness Temperature setting?
2. How much shrinkage was experienced?
3. State the natural laws that apply.
Turn in Summary
15
Culinology: Food Thermoisturization
C. 01/15/03 Winston L. Shelton
Glossary of Terms
(From Webster’s Third New International Dictionary, except for items marked with *).
Cloud: Visible assemblage of droplets of water.
Conduction heat transfer: The transfer of heat through matter through communication of kinetic energy
from particle to particle rather than by a flow of heated material.
Convection heat transfer: The transfer of heat through the circulation of a fluid.
*Culinology: The science of the application of culinary knowledge.
Dry Bulb Temperature: Temperature indicated by a dry bulb thermometer that is the actual temperature
of the air.
Enthalpy:
The absolute enthalpy of a substance at any temperature is the quantity of heat necessary to
raise its temperature from absolute zero to the temperature. This quantity includes the sensible heat, the
latent heat, and any heat absorbed by other changes in state.
Entropy: The energy or heat in the system that is not available for doing work. e. g., In food preparation:
When heating foods in an oven, the amount of heat in the air below the temperature of the foods being
heated cannot be given up to the foods to heat them.)
Equilibrium: A state of balance between or among opposing forces or processes resulting in the
absence of net change.
Fog: Fine particles of water suspended in the lower atmosphere usual resulting from condensation of
water vapor in the atmosphere.
Gas: A compressible fluid (as air) that has neither independent shape nor volume but tends to expand
indefinitely.
Humidity (Also Absolute Humidity): The weight of water vapor in a pound of dry air.
Latent Heat: Thermal energy (as heat of vaporization or condensation) involved in a process that is not
characterized by a change in temperature. Contrast Sensible Heat.
Liquid: A slightly compressible fluid (as water) having a definite volume without having a definite shape
and that is incapable of indefinite expansion.
Mist: Water in the form of particles suspended in the atmosphere at or near the surface of the earth.
Radiation heat transfer: The process of emitting radiant energy in the form of waves of energy
distinguished from other forms of heat transfer by its speed of propagation which equals that of light, and
by the fact the no intervening medium is required for its transmission.
Culinology: Food Thermoisturization
16
C. 01/15/03 Winston L. Shelton
Relative Humidity: The moisture content of atmospheric air expressed in the percentage, from the ratio
of the partial pressure of water in the air to the saturation pressure at the temperature of the air.
Sensible Heat: Thermal energy involved in a process involving a change in temperature. Contrast latent
heat.
Specific Heat: The ratio of the quantity of heat required to increase the temperature of a body in a
specified state to that required to increase the temperature on an equal mass of water through the same
temperature. This definition has the effect of identifying the specific heat of water as 1.
Steam: Water in the state of vapor.
*Thermoisturization Technology: The study of controlling food temperature and food moisture through
the control of Wet Bulb Temperature (Food Equilibrium Temperature, Tfe) and the difference between the
Air Dry Bulb Temperature and Air Wet Bulb Temperature (Evaporation Temperature, TE).
*Thermoisturize: Taken from the words thermalize and moisturize… to mean the process of
thermalizing while moisturizing. Also thermoisturization, and other forms.
Vapor: A substance in the gaseous state as distinguished from the liquid or solid state.
Wet Bulb Temperature: Temperature indicated by a thermometer with moistened bulb.
Culinology: Food Thermoisturization
17
C. 01/15/03 Winston L. Shelton
Water Vapor Pressure versus Water Temperature
32F
.08854 psi
35
.09995
40
.12170
45
.14752
50
.17811
60
.2563
70
.3031
80
.5069
90
.6982
100
.9492
110
1.2748
120
1.6924
130
2.2225
140
2.8886
150
3.718
160
4.741
170
5.992
180
7.510
190
9.339
200
11.526
210
14.123
212
14.696
18
Culinology: Food Thermoisturization
C. 01/15/03 Winston L. Shelton
Percent Relative Humidity versus Wet and Dry Bulb Temperatures
Dry
Wet Bulb Temperature (F)
Bulb
90
100
110
120
130
140
150
160
170
180
190
200
210
100
68%
100
110
47%
70%
100
120
32%
50%
72%
100
130
22%
36%
53%
74%
100
140
15%
25%
39%
55%
75%
100
150
10%
18%
28%
41%
57%
76%
100
160
7%
13%
21%
31%
43%
58%
77%
100
170
4%
9%
16%
23%
33%
45%
60%
78%
100
180
3%
7%
12%
18%
26%
35%
47%
61%
79%
100
190
2%
5%
9%
14%
20%
27%
37%
48%
62%
79%
100
200
1%
3%
7%
11%
16%
22%
29%
39%
50%
64%
80%
100
210
0%
2%
5%
8%
12%
17%
23%
31%
40%
51%
65%
81%
100
220
0%
2%
4%
6%
10%
14%
19%
25%
32%
41%
52%
66%
81%
230
0%
1%
3%
5%
8%
11%
15%
20%
26%
34%
43%
54%
66%
240
0%
1%
2%
4%
6%
9%
12%
16%
21%
28%
35%
44%
55%
250
0%
0%
2%
3%
5%
7%
10%
13%
18%
23%
29%
36%
45%
260
0%
0%
1%
2%
4%
6%
8%
11%
15%
19%
24%
30%
38%
270
0%
0%
1%
2%
3%
5%
7%
9%
12%
16%
20%
25%
31%
280
0%
0%
1%
1%
3%
4%
6%
8%
10%
13%
17%
21%
26%
290
0%
0%
0%
1%
2%
3%
5%
6%
8%
11%
14%
18%
22%
300
0%
0%
0%
1%
2%
3%
4%
5%
7%
9%
12%
15%
19%
320
0%
0%
0%
1%
1%
2%
3%
4%
5%
7%
9%
11%
14%
340
0%
0%
0%
0%
1%
1%
2%
3%
4%
5%
6%
8%
10%
360
0%
0%
0%
0%
0%
1%
1%
2%
3%
4%
5%
6%
8%
380
0%
0%
0%
0%
0%
1%
1%
1%
2%
3%
4%
5%
6%
400
0%
0%
0%
0%
0%
0%
1%
1%
2%
2%
3%
3%
4%
Percent Relative Humidity versus Wet and Dry Bulb Temperatures
19
Culinology: Food Thermoisturization
Dry
C. 01/15/03 Winston L. Shelton
Wet Bulb Temperature (F)
Bulb
20
30
40
50
60
70
80
90
100
20
30
40
23% 100%
50
38% 100%
60
5%
48% 100%
70
19% 55% 100%
80
4%
29% 61% 100%
90
13% 36%
100
4%
65 100%
21% 41%
68
100%