Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Dynamic insulation wikipedia , lookup
Hypothermia wikipedia , lookup
Radiator (engine cooling) wikipedia , lookup
R-value (insulation) wikipedia , lookup
Solar air conditioning wikipedia , lookup
Intercooler wikipedia , lookup
Thermal conduction wikipedia , lookup
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 70F 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 60F (for example) is reached. When cooling stops, a condition of 60F is therefore identified as the wet bulb temperature. (A chart can now be entered with the 70F dry bulb temperature and the 60F 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 60F, 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 60F, condensation discontinues; however the difference between the dry bulb temperature and the food temperature is 10F (in our example), so heat continues to flow from the 70F air to the food. The effect of this heat flow however is not the continuation of the march of food temperature to the 70F 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 60F wet bulb temperature/70F 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 70F to approach the 60F value of the wet bulb thermometer, less and less heat is delivered to the wet wick. Finally, as the air dry bulb temperature reaches 60F, 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 212F. Few people can put foods hotter than 150F in their mouth. Yet traditional cooking equipment cooks at temperatures of up to 600F; 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 135F (for example) and cook prime rib to 135F without any concern for overcooking. With the dry bulb control set at 145F, the driving force to evaporate moisture is only 10F. 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 80F, determine the relative humidity of the room (from nearest 10F 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 160F. 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 100F; set Dry – Wet Bulb Temperature at 0F; 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 40F and record temperatures every 5 minutes until temperatures have stabilized. 6. With Wet Bulb Temperature set at 140F, increase Dry – Wet Bulb Temperature by 40F 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 40F? 2. How much did the potato slice temperature change when the dry bulb temperature was increased over the wet bulb temperature by 40F? 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 140F; set Dry – Wet Bulb Temperature at 0F; 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 = 140F, Dry – Wet Bulb Temp = 40F. 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 135F; 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 32F .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%