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Electrical Energy Used and Time Consumed When Cooking Foods by Various Home Methods: Eggs
Electrical Energy Used and Time Consumed When Cooking Foods by Various Home Methods: Eggs R. C. BAKER1, J. M. DARFLER1, and G. E. REHKUGLER2 Departments of Poultry Science and Agricultural Engineering, Cornell University, Ithaca, New York 14853
(Received for publication February 20, 1979)
INTRODUCTION We have been made aware these last few years of the importance of energy conservation. We have been advised to add insulation to our homes, to turn the thermostat down, and to drive smaller cars. It is also of interest to take a look at the energy required to cook some of the foods that are served regularly in many homes, and that are commonly cooked many ways, in order to determine which methods are more economical of energy. Since eggs are cooked by many methods, they were selected for this study. Egg cooking methods have been the subject of considerable research. Essary (1967) determined the composition of eggs cooked by many home methods. Cimino et al. (1967) froze souffles and meringues and evaluated their stability. Irmiter et al. (1970) hard cooked eggs several ways to determine which produced the least cracks and easiest peeling. Tuttle et al. (1972) scrambled eggs made from several egg solids products and used consumer panels to evaluate their acceptability in comparison with scrambled eggs made from fresh eggs. Several researchers have recorded the energy and time used in cooking foods by several different appliances. These foods include top round of beef (Marshall, 1960), a selected meal
1 1
Department of Poultry Science. Department of Agricultural Engineering.
(Harris, 1974), beef patties (Rhee and Drew, 1977), and meat loaf and beef roast (Drew and Rhee, 1978). No research appears to have been done, however, on a comparison of egg cooking methods on the basis of energy and time consumption, which is the subject of this study.
MATERIALS AND METHODS All top stove cooking was done on a two element portable electric range (Presto model 01/PR2P, National Presto Ind., Eau Claire, WI) rated at 120 volts, 60 cycles, 1650 watts (1100 watts for the large element, 550 watts for the small element). The large element only was used. Heat markings were Low, 1, to High, 6. Energy used was determined in watt hours (Wh) by an appliance meter (Duncan Electric Co., LaFayette, IN) which is rated at 15 amp max, 2 wire, 115 volts, 60 cycles. Oven cooking was done in an electric oven (Hotpoint model RJ 15-B, Hotpoint, Chicago, IL) and in a toaster oven (General Electric model A5 3126 General Electric, Bridgeport, CT) rated at 120 volts, 50 to 60 cycles, 1500 watts. Energy consumed by the electric oven was determined by an appliance meter (Duncan Electric Co., LaFayette, IN) which is rated at 35 amp max, 3 wire, 230 volts, 60 cycles. Microwave cooking was done in an Amana Radarange (Model RR 3H, Amana Refrigeration, Inc., Amana, IA) rated at 1600 watts. Consumption of electrical energy and time was recorded for each method.
545
Downloaded from http://ps.oxfordjournals.org/ at Serials Acq (Law) on May 24, 2015
ABSTRACT Eggs were cooked by various home style methods in order to determine which methods were more economical of energy. Electrical energy consumed was measured by a watt meter. Eggs were cooked by 1) soft and hard cooking, 2) scrambling (top stove and microwave), 3) frying, 4) poaching, 5) omelets, and 6) oven baked (shirring). Energy saving methods were those which reduced heat losses by taking advantage of 1) the heat stored in water (hard cooked), 2) the heat saved by covering the utensil (fried eggs, covered), or 3) equipment which used less water to accomplish the same results (poaching eggs in an egg poacher). 1980 Poultry Science 59:545-549
546
BAKER ET AL.
were heated at #4, or moderate heat, for 2 min in a covered Teflon-lined 20.3 cm (8 in) aluminum frying pan. Four eggs were carefully broken out into a bowl and added to the frying pan which was then re-covered. Cooking was continued until all albumen was coagulated while the yolk remained fluid. Sunny side up — The previous 2 methods of cooking fried eggs were selected because the end products are very similar. However, many consumers prefer their fried eggs sunny side up. This method was the same as for over easy, except that the eggs were cooked to the same degree of doneness without turning. Poached. In water — One liter of water, sufficient to float the eggs, was heated to boiling on "High" in a covered 20.3 cm (8 in) Teflon-lined aluminum frying pan. Four broken out eggs were gently added to the water and cooked until all the albumen was coagulated. In egg poacher with 4 individual cups — Two hundred twenty-five milliliters water at 10 C were put in the bottom part and brought to a boil on "High". Four eggs were put into the buttered cups, covered, and cooked until all albumen was coagulated. Omelets. Omelets were made with 4 eggs, but 2 eggs at a time, which is the preferred method for making omelets (Child, 1975; Beard, 1977). The eggs, 15 ml cold water, and 1.5 g salt were beaten with a fork. A 20.3 cm (8 in) Teflon-lined aluminum frying pan was heated on "High" for 3 min, and butter (15 g) was added and melted. The eggs were added and the pan was shaken to stir the eggs until all material was coagulated. The omelet was rolled onto a plate with the aid of a spoon and the pan • reheated for the second omelet. It was made in the same manner with the remaining two eggs. Total time and energy used was recorded for the two omelets.
Cold water start — Four eggs and 600 ml of tap water (10 C), sufficient to cover the eggs, were brought to a boil on "High" in a 181.2 ml (2 qt) covered saucepan. The pan was removed from the element and left to stand for 25 min. The water was poured off and the eggs were cooled in running tap water for 5 min. Scrambled. Top stove — A 20.3 cm (8 in) aluminum frying pan containing 10 ml vegetable oil was heated on "High" for 2 min. Four eggs were beaten with 50 ml water and 3 g salt, added to the frying pan, and stirred with a spoon until all material was just coagulated. Time and energy were recorded. Cooking was continued until eggs were firmly coagulated, and time and energy were recorded. Microwave — Four eggs were broken into a 136.2 ml (1 1/2 qt) Pyrex casserole, and mixed with 50 ml water, 2 g salt, and 15 g butter. Eggs Shirred (Baked) Eggs. Oven — The oven was were cooked 1 min, stirred, cooked 1 min, stirred, cooked 3/4 min (until done for soft preheated to 176 C. Ten grams butter were put scrambled eggs), then cooked 1/4 min longer into each of four 141.5 ml (5 ounce) Pyrex custard cups, the eggs were broken into the for firmly coagulated scrambled eggs. Fried. Over easy — Fifteen milliliters of custard cups, and the cups were put on a vegetable oil were heated in a Teflon-lined 20.3 small metal tray. The assemblage was put in the cm (8 in) aluminum frying pan for 3 min on preheated oven and baked for 10 min at which •#4, or moderate heat. Four eggs were carefully time the albumen was coagulated but the yolk broken out into a bowl and added to the frying was still liquid. pan. When the albumen was nearly coagulated, Toaster oven — The same procedure was the eggs were turned over and cooked until the followed for cooking in a small toaster oven. albumen was fully coagulated, but the yolk The theoretical energy required to cook the remained fluid. eggs was determined on the basis of the energy Covered — Fifteen milliliters of vegetable oil required to: a) elevate the temperature of the
Downloaded from http://ps.oxfordjournals.org/ at Serials Acq (Law) on May 24, 2015
All eggs, obtained from the Cornell Poultry Farm, medium size and 2 to 6 days old, were brought to room temperature before cooking. Four eggs were used for each method and each method was repeated 3 times. The cooking methods used were selected because they are commonly used in the home. Procedures were as follows. Soft Cooked. Six hundred milliliters of cold (10 C) tap water, sufficient to cover the eggs, were brought to a boil on "High", in a 181.2 ml (2 qt) covered aluminum pan and 4 eggs were added. Eggs were cooked for 3, 4, and 5 min. Hard Cooked. Boiling water start — Six hundred milliliters of tap water (10 C), sufficient to cover the eggs, were brought to a boil on "High" in a 181.2 ml (2 qt) covered aluminum saucepan. Four eggs were added. When the water returned to a simmer (91 to 93 C), the heat was turned to #2. The eggs were cooked for 15 min then cooled for 5 min in running tap water.
ENERGY AND EGG COOKING eggs and ingredients from 20 C t o 70 C, t h e t e m p e r a t u r e at which most of t h e egg albumen was coagulated ( R o m a n o f f and Romanoff, 1 9 4 9 ) ; b) elevate t h e t e m p e r a t u r e of t h e utensil from 2 0 C t o 100 C (to 130 C for b a k e d eggs); and c) elevate t h e water used in cooking from 2 0 C t o 1 0 0 C. F o r t h e microwave oven t h e utensil energy was n o t included and in t h e case of shirred eggs t h e energy required t o elevate t h e oven t e m p e r a t u r e was n o t d e t e r m i n e d . T h e basic form of t h e calculations was: Energy = mass of material x specific heat X t e m p e r a t u r e rise. T h e specific heats used in t h e calculations
547
were: egg, . 7 9 ; a l u m i n u m utensil, . 2 1 8 ; glass, .20; and water, 1.0. Utensil weights and w a t e r weights were measured on a l a b o r a t o r y scale. T h e weight of t h e four eggs was assumed t o be 2 2 4 g for t h e eggs with shells and 2 0 0 g for t h e eggs w i t h o u t shells.
RESULTS AND DISCUSSION Soft cooked eggs cooked 5 min only slightly m o r e energy than when min, since m o s t of t h e energy was bringing t h e water t o a boil, and
required cooked 3 used for little for
Total energy (Wh).b
Cooking method
Total cooking time a (rain)
Soft cooked d 3 min (1) 4 min (2) 5 min (3)
10 11 12
80.3 80.3 80.3
144 147 150
Hard cooked Cold start (4) Boiling start (5)
8 22
80.3 80.3
136 183
4 4.25
21.7 21.7
68 73
2.75 3
12.4 C 12.4 C
75 80
5.25 4.25 6
18.9 21.3 18.9
90 74 93
123.2 42.9
230 111
19.9
92
Scrambled Top stove Soft (6) Firm (7) Microwave Soft (8) Firm (9) Fried Over easy (10) Covered (11) Sunny side up (12) Poached In water (13) In poacher (14)
13
Omelet (15) Shirred (baked) Oven Bake Total (16)
10 10 20
Toaster oven Preheat Bake Total (17)
6 10 16
Average of three trials per method, four eggs per trial. Wh = watt hours. c
Excluding energy to elevate the oven temperature. Numbers correspond'to numbers in Figure 1.
Theoretical
18.9
C
18.9
C
Experimental
472 92 564 69 55 124
Downloaded from http://ps.oxfordjournals.org/ at Serials Acq (Law) on May 24, 2015
TABLE 1. Time and electrical energy expended in cookingeggs by various home methods
548
BAKER ET AL.
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HUBERS REFER TO CCOKINC ttTHODS - TABLE 1
nl 0
1 2
1 4 TOTAL
1 1 6 8 COOKING
1 1 I 1 0 1 2 14 TIME - MINUTES
I 16
v '
1 22
FIG. 1. Experimental egg cooking energy vs. time for various cooking methods.
the experimental ranking of energy demands for cooking eggs. The theoretical analysis predicts and experimental data confirms that the methods that require elevating the temperature of large equipment and/or utensils and large amounts of heated water relative to the amount of food prepared can result in excessive energy needed for food preparation. In conclusion, to produce essentially the same results in cooking eggs, some methods are more conserving of time and electrical energy than are others. The energy saving methods are those which reduce losses by taking advantage of 1) the heat stored in water (hard cooked), 2) the heat saved by covering the cooking utensil (fried eggs, covered), or 3) equipment which uses less water to accomplish the same results (poaching eggs in egg poacher). In addition, the least energy is required for the cooking method that brings the food in direct contact with the cooking surface. In the next most efficient method, the food is contained in a small utensil and is surrounded by water as the heat transfer medium. The least efficient method uses air as a heat transfer medium and also requires that a very large mass of metal (i.e., oven walls) be heated. Methods in which a great deal of residual heat remained in the cooking system (pan and water or oven walls) were wasteful. ACKNOWLEDGMENT The authors would like to thank Mary Purchase, College of Human Ecology, Cornell University, for her constructive criticism of the manuscript. REFERENCES Beard, J., 1977. Theory and practice of good cooking. Alfred A. Knopf, New York, NY. Child, J., 1975. From Julia Child's kitchen. Alfred A.
Downloaded from http://ps.oxfordjournals.org/ at Serials Acq (Law) on May 24, 2015
maintaining temperature once the eggs were in the water and the water brought back to a boil (Table 1). Hard cooked eggs cooked by starting in cold water, bringing to a boil and allowing to stand 25 min with the heat off required a cooking time only one-third as long compared to hard cooked eggs cooked from a boiling water start. Considerably less energy was used for the former method also (136 Wh vs. 183 Wh) by taking advantage of the stored heat in the water. Total time involved in hard cooking the eggs, however, was longer due to the extra 25 min of standing time after removing from heat. Scrambling eggs in a microwave oven vs. on top of the stove showed that very little time and no energy was saved by cooking in the microwave oven. In fact, the microwave oven used slightly more electrical energy than the top stove method. Frying eggs to a comparable stage of doneness showed that cooking in a covered frying pan saved little time and a small amount of electrical energy over the over easy method. Fried, sunny side up, required very slightly more time and electrical energy than over easy since the eggs were cooked from one side only. Poaching eggs in a four unit egg poaching pan saved one-third of the time and required about half of the electrical energy required to poach the four eggs in a frying pan containing water. The time and energy required to heat sufficient water to float the eggs in the frying pan was greater than the amount required to create the steam which cooks the eggs in the egg poaching pan. Omelets required little more time and energy than the other top stove non-boiling methods of cooking eggs, such as frying and scrambling, even though only half of the four egg lot could be cooked at one time. Figure 1 shows a relationship between energy required and the total cooking time, with baking methods excluded. The baking methods were omitted because there was insufficient data for the temperature and mass of the appliances for a theoretical calculation of energy input. The implication is that whatever the method, if more time is required, then more energy is required. Methods of cooking eggs that utilized the least amount of equipment and the least amount of water require the least amount of energy and time. With the baking methods excluded, the theoretical ranking of methods nearly parallels
ENERGY AND EGG COOKING Knopf, New York, NY. Cimino, S. L., L. F. Elliott, and H. H. Palmer, 1967. The stability of souffles and meringues subjected to frozen storage. Food Technol. 21:1149-1152. Drew, F., and K. S. Rhee, 1978. Fuel consumption by cooking appliances. J. Amer. Diet Ass. 72: 37-44. Essary, E. O., 1967. Composition of eggs as influenced by cooking methods. Poultry Sci. 46: 1254-1255. Harris, J. L., 1974. Energy used by five electrical appliances cooking a specific food load. Master's thesis, Colorado State University, unpublished. Irmiter, J. F., L. E. Dawson, and J. G. Reagan, 1970.
549
Methods of preparing hard cooked eggs. Poultry Sci. 49:1232-1236. Marshall, N., 1960. Electronic cookery of top round of beef. J. Home Econ. 52:31-34. Rhee, K. S., and F. Drew, 1977. Energy consumption and acceptability comparison of cooking methods and appliances for beef patties. Home Econ. Res. J. 5:269-282. Romanoff, A. L., and A. J. Romanoff, 1949. The avian egg. John Wiley and Sons, New York, NY. Tuttle, J. W., J. H. Wolford, H. E. Larzelere and L. E. Dawson, 1972. Acceptability of scrambled eggs from egg solids products. Poultry Sci. 51:56-59.
Downloaded from http://ps.oxfordjournals.org/ at Serials Acq (Law) on May 24, 2015
(Received for publication February 20, 1979)
INTRODUCTION We have been made aware these last few years of the importance of energy conservation. We have been advised to add insulation to our homes, to turn the thermostat down, and to drive smaller cars. It is also of interest to take a look at the energy required to cook some of the foods that are served regularly in many homes, and that are commonly cooked many ways, in order to determine which methods are more economical of energy. Since eggs are cooked by many methods, they were selected for this study. Egg cooking methods have been the subject of considerable research. Essary (1967) determined the composition of eggs cooked by many home methods. Cimino et al. (1967) froze souffles and meringues and evaluated their stability. Irmiter et al. (1970) hard cooked eggs several ways to determine which produced the least cracks and easiest peeling. Tuttle et al. (1972) scrambled eggs made from several egg solids products and used consumer panels to evaluate their acceptability in comparison with scrambled eggs made from fresh eggs. Several researchers have recorded the energy and time used in cooking foods by several different appliances. These foods include top round of beef (Marshall, 1960), a selected meal
1 1
Department of Poultry Science. Department of Agricultural Engineering.
(Harris, 1974), beef patties (Rhee and Drew, 1977), and meat loaf and beef roast (Drew and Rhee, 1978). No research appears to have been done, however, on a comparison of egg cooking methods on the basis of energy and time consumption, which is the subject of this study.
MATERIALS AND METHODS All top stove cooking was done on a two element portable electric range (Presto model 01/PR2P, National Presto Ind., Eau Claire, WI) rated at 120 volts, 60 cycles, 1650 watts (1100 watts for the large element, 550 watts for the small element). The large element only was used. Heat markings were Low, 1, to High, 6. Energy used was determined in watt hours (Wh) by an appliance meter (Duncan Electric Co., LaFayette, IN) which is rated at 15 amp max, 2 wire, 115 volts, 60 cycles. Oven cooking was done in an electric oven (Hotpoint model RJ 15-B, Hotpoint, Chicago, IL) and in a toaster oven (General Electric model A5 3126 General Electric, Bridgeport, CT) rated at 120 volts, 50 to 60 cycles, 1500 watts. Energy consumed by the electric oven was determined by an appliance meter (Duncan Electric Co., LaFayette, IN) which is rated at 35 amp max, 3 wire, 230 volts, 60 cycles. Microwave cooking was done in an Amana Radarange (Model RR 3H, Amana Refrigeration, Inc., Amana, IA) rated at 1600 watts. Consumption of electrical energy and time was recorded for each method.
545
Downloaded from http://ps.oxfordjournals.org/ at Serials Acq (Law) on May 24, 2015
ABSTRACT Eggs were cooked by various home style methods in order to determine which methods were more economical of energy. Electrical energy consumed was measured by a watt meter. Eggs were cooked by 1) soft and hard cooking, 2) scrambling (top stove and microwave), 3) frying, 4) poaching, 5) omelets, and 6) oven baked (shirring). Energy saving methods were those which reduced heat losses by taking advantage of 1) the heat stored in water (hard cooked), 2) the heat saved by covering the utensil (fried eggs, covered), or 3) equipment which used less water to accomplish the same results (poaching eggs in an egg poacher). 1980 Poultry Science 59:545-549
546
BAKER ET AL.
were heated at #4, or moderate heat, for 2 min in a covered Teflon-lined 20.3 cm (8 in) aluminum frying pan. Four eggs were carefully broken out into a bowl and added to the frying pan which was then re-covered. Cooking was continued until all albumen was coagulated while the yolk remained fluid. Sunny side up — The previous 2 methods of cooking fried eggs were selected because the end products are very similar. However, many consumers prefer their fried eggs sunny side up. This method was the same as for over easy, except that the eggs were cooked to the same degree of doneness without turning. Poached. In water — One liter of water, sufficient to float the eggs, was heated to boiling on "High" in a covered 20.3 cm (8 in) Teflon-lined aluminum frying pan. Four broken out eggs were gently added to the water and cooked until all the albumen was coagulated. In egg poacher with 4 individual cups — Two hundred twenty-five milliliters water at 10 C were put in the bottom part and brought to a boil on "High". Four eggs were put into the buttered cups, covered, and cooked until all albumen was coagulated. Omelets. Omelets were made with 4 eggs, but 2 eggs at a time, which is the preferred method for making omelets (Child, 1975; Beard, 1977). The eggs, 15 ml cold water, and 1.5 g salt were beaten with a fork. A 20.3 cm (8 in) Teflon-lined aluminum frying pan was heated on "High" for 3 min, and butter (15 g) was added and melted. The eggs were added and the pan was shaken to stir the eggs until all material was coagulated. The omelet was rolled onto a plate with the aid of a spoon and the pan • reheated for the second omelet. It was made in the same manner with the remaining two eggs. Total time and energy used was recorded for the two omelets.
Cold water start — Four eggs and 600 ml of tap water (10 C), sufficient to cover the eggs, were brought to a boil on "High" in a 181.2 ml (2 qt) covered saucepan. The pan was removed from the element and left to stand for 25 min. The water was poured off and the eggs were cooled in running tap water for 5 min. Scrambled. Top stove — A 20.3 cm (8 in) aluminum frying pan containing 10 ml vegetable oil was heated on "High" for 2 min. Four eggs were beaten with 50 ml water and 3 g salt, added to the frying pan, and stirred with a spoon until all material was just coagulated. Time and energy were recorded. Cooking was continued until eggs were firmly coagulated, and time and energy were recorded. Microwave — Four eggs were broken into a 136.2 ml (1 1/2 qt) Pyrex casserole, and mixed with 50 ml water, 2 g salt, and 15 g butter. Eggs Shirred (Baked) Eggs. Oven — The oven was were cooked 1 min, stirred, cooked 1 min, stirred, cooked 3/4 min (until done for soft preheated to 176 C. Ten grams butter were put scrambled eggs), then cooked 1/4 min longer into each of four 141.5 ml (5 ounce) Pyrex custard cups, the eggs were broken into the for firmly coagulated scrambled eggs. Fried. Over easy — Fifteen milliliters of custard cups, and the cups were put on a vegetable oil were heated in a Teflon-lined 20.3 small metal tray. The assemblage was put in the cm (8 in) aluminum frying pan for 3 min on preheated oven and baked for 10 min at which •#4, or moderate heat. Four eggs were carefully time the albumen was coagulated but the yolk broken out into a bowl and added to the frying was still liquid. pan. When the albumen was nearly coagulated, Toaster oven — The same procedure was the eggs were turned over and cooked until the followed for cooking in a small toaster oven. albumen was fully coagulated, but the yolk The theoretical energy required to cook the remained fluid. eggs was determined on the basis of the energy Covered — Fifteen milliliters of vegetable oil required to: a) elevate the temperature of the
Downloaded from http://ps.oxfordjournals.org/ at Serials Acq (Law) on May 24, 2015
All eggs, obtained from the Cornell Poultry Farm, medium size and 2 to 6 days old, were brought to room temperature before cooking. Four eggs were used for each method and each method was repeated 3 times. The cooking methods used were selected because they are commonly used in the home. Procedures were as follows. Soft Cooked. Six hundred milliliters of cold (10 C) tap water, sufficient to cover the eggs, were brought to a boil on "High", in a 181.2 ml (2 qt) covered aluminum pan and 4 eggs were added. Eggs were cooked for 3, 4, and 5 min. Hard Cooked. Boiling water start — Six hundred milliliters of tap water (10 C), sufficient to cover the eggs, were brought to a boil on "High" in a 181.2 ml (2 qt) covered aluminum saucepan. Four eggs were added. When the water returned to a simmer (91 to 93 C), the heat was turned to #2. The eggs were cooked for 15 min then cooled for 5 min in running tap water.
ENERGY AND EGG COOKING eggs and ingredients from 20 C t o 70 C, t h e t e m p e r a t u r e at which most of t h e egg albumen was coagulated ( R o m a n o f f and Romanoff, 1 9 4 9 ) ; b) elevate t h e t e m p e r a t u r e of t h e utensil from 2 0 C t o 100 C (to 130 C for b a k e d eggs); and c) elevate t h e water used in cooking from 2 0 C t o 1 0 0 C. F o r t h e microwave oven t h e utensil energy was n o t included and in t h e case of shirred eggs t h e energy required t o elevate t h e oven t e m p e r a t u r e was n o t d e t e r m i n e d . T h e basic form of t h e calculations was: Energy = mass of material x specific heat X t e m p e r a t u r e rise. T h e specific heats used in t h e calculations
547
were: egg, . 7 9 ; a l u m i n u m utensil, . 2 1 8 ; glass, .20; and water, 1.0. Utensil weights and w a t e r weights were measured on a l a b o r a t o r y scale. T h e weight of t h e four eggs was assumed t o be 2 2 4 g for t h e eggs with shells and 2 0 0 g for t h e eggs w i t h o u t shells.
RESULTS AND DISCUSSION Soft cooked eggs cooked 5 min only slightly m o r e energy than when min, since m o s t of t h e energy was bringing t h e water t o a boil, and
required cooked 3 used for little for
Total energy (Wh).b
Cooking method
Total cooking time a (rain)
Soft cooked d 3 min (1) 4 min (2) 5 min (3)
10 11 12
80.3 80.3 80.3
144 147 150
Hard cooked Cold start (4) Boiling start (5)
8 22
80.3 80.3
136 183
4 4.25
21.7 21.7
68 73
2.75 3
12.4 C 12.4 C
75 80
5.25 4.25 6
18.9 21.3 18.9
90 74 93
123.2 42.9
230 111
19.9
92
Scrambled Top stove Soft (6) Firm (7) Microwave Soft (8) Firm (9) Fried Over easy (10) Covered (11) Sunny side up (12) Poached In water (13) In poacher (14)
13
Omelet (15) Shirred (baked) Oven Bake Total (16)
10 10 20
Toaster oven Preheat Bake Total (17)
6 10 16
Average of three trials per method, four eggs per trial. Wh = watt hours. c
Excluding energy to elevate the oven temperature. Numbers correspond'to numbers in Figure 1.
Theoretical
18.9
C
18.9
C
Experimental
472 92 564 69 55 124
Downloaded from http://ps.oxfordjournals.org/ at Serials Acq (Law) on May 24, 2015
TABLE 1. Time and electrical energy expended in cookingeggs by various home methods
548
BAKER ET AL.
OT 2 0 0 -
^
tiso-
„
>• ' 0 0 z
J i K f
9
£
j ^ i ^ l 5Q
^
^
^
'
^
r
iJr<3 R = .72 DEGRESSION " SIGN,
UJ
^
AT
33,36
> 1'LEVEL
HUBERS REFER TO CCOKINC ttTHODS - TABLE 1
nl 0
1 2
1 4 TOTAL
1 1 6 8 COOKING
1 1 I 1 0 1 2 14 TIME - MINUTES
I 16
v '
1 22
FIG. 1. Experimental egg cooking energy vs. time for various cooking methods.
the experimental ranking of energy demands for cooking eggs. The theoretical analysis predicts and experimental data confirms that the methods that require elevating the temperature of large equipment and/or utensils and large amounts of heated water relative to the amount of food prepared can result in excessive energy needed for food preparation. In conclusion, to produce essentially the same results in cooking eggs, some methods are more conserving of time and electrical energy than are others. The energy saving methods are those which reduce losses by taking advantage of 1) the heat stored in water (hard cooked), 2) the heat saved by covering the cooking utensil (fried eggs, covered), or 3) equipment which uses less water to accomplish the same results (poaching eggs in egg poacher). In addition, the least energy is required for the cooking method that brings the food in direct contact with the cooking surface. In the next most efficient method, the food is contained in a small utensil and is surrounded by water as the heat transfer medium. The least efficient method uses air as a heat transfer medium and also requires that a very large mass of metal (i.e., oven walls) be heated. Methods in which a great deal of residual heat remained in the cooking system (pan and water or oven walls) were wasteful. ACKNOWLEDGMENT The authors would like to thank Mary Purchase, College of Human Ecology, Cornell University, for her constructive criticism of the manuscript. REFERENCES Beard, J., 1977. Theory and practice of good cooking. Alfred A. Knopf, New York, NY. Child, J., 1975. From Julia Child's kitchen. Alfred A.
Downloaded from http://ps.oxfordjournals.org/ at Serials Acq (Law) on May 24, 2015
maintaining temperature once the eggs were in the water and the water brought back to a boil (Table 1). Hard cooked eggs cooked by starting in cold water, bringing to a boil and allowing to stand 25 min with the heat off required a cooking time only one-third as long compared to hard cooked eggs cooked from a boiling water start. Considerably less energy was used for the former method also (136 Wh vs. 183 Wh) by taking advantage of the stored heat in the water. Total time involved in hard cooking the eggs, however, was longer due to the extra 25 min of standing time after removing from heat. Scrambling eggs in a microwave oven vs. on top of the stove showed that very little time and no energy was saved by cooking in the microwave oven. In fact, the microwave oven used slightly more electrical energy than the top stove method. Frying eggs to a comparable stage of doneness showed that cooking in a covered frying pan saved little time and a small amount of electrical energy over the over easy method. Fried, sunny side up, required very slightly more time and electrical energy than over easy since the eggs were cooked from one side only. Poaching eggs in a four unit egg poaching pan saved one-third of the time and required about half of the electrical energy required to poach the four eggs in a frying pan containing water. The time and energy required to heat sufficient water to float the eggs in the frying pan was greater than the amount required to create the steam which cooks the eggs in the egg poaching pan. Omelets required little more time and energy than the other top stove non-boiling methods of cooking eggs, such as frying and scrambling, even though only half of the four egg lot could be cooked at one time. Figure 1 shows a relationship between energy required and the total cooking time, with baking methods excluded. The baking methods were omitted because there was insufficient data for the temperature and mass of the appliances for a theoretical calculation of energy input. The implication is that whatever the method, if more time is required, then more energy is required. Methods of cooking eggs that utilized the least amount of equipment and the least amount of water require the least amount of energy and time. With the baking methods excluded, the theoretical ranking of methods nearly parallels
ENERGY AND EGG COOKING Knopf, New York, NY. Cimino, S. L., L. F. Elliott, and H. H. Palmer, 1967. The stability of souffles and meringues subjected to frozen storage. Food Technol. 21:1149-1152. Drew, F., and K. S. Rhee, 1978. Fuel consumption by cooking appliances. J. Amer. Diet Ass. 72: 37-44. Essary, E. O., 1967. Composition of eggs as influenced by cooking methods. Poultry Sci. 46: 1254-1255. Harris, J. L., 1974. Energy used by five electrical appliances cooking a specific food load. Master's thesis, Colorado State University, unpublished. Irmiter, J. F., L. E. Dawson, and J. G. Reagan, 1970.
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Methods of preparing hard cooked eggs. Poultry Sci. 49:1232-1236. Marshall, N., 1960. Electronic cookery of top round of beef. J. Home Econ. 52:31-34. Rhee, K. S., and F. Drew, 1977. Energy consumption and acceptability comparison of cooking methods and appliances for beef patties. Home Econ. Res. J. 5:269-282. Romanoff, A. L., and A. J. Romanoff, 1949. The avian egg. John Wiley and Sons, New York, NY. Tuttle, J. W., J. H. Wolford, H. E. Larzelere and L. E. Dawson, 1972. Acceptability of scrambled eggs from egg solids products. Poultry Sci. 51:56-59.
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