; fwt‘” ‘ q i - I“. . a» . y y . NOV 2 1 2005 THE EFFECT OF HOMOGENIZATION ON THE GELATION AND PALATABILITY OF BAKED CUSTARDS PREPARED WITH DRIED WHOLE EGG SOLIDS BY Marjorie Eleanor Mastic AN ABSTRACT Submitted to the College of Home Economics Michigan State University of.Agriculture and Applied Science in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Foods and Nutrition 1959 Approved W 797' W ’ é/ Marjorie Eleanor Mastic ABSTRACT The effect of homogenization on the firmness of gel structure and palatability of baked custards pre- pared with 2 concentrations of Spray-dried whole egg solids (DWES) were studied. In the preparation of the custards from a stand- ard recipe, dried egg solids were substituted for fresh eggs on a weight basis. Custards with a low concentration of egg contained an additional amount of milk equivalent in weight to the water necessary to reconstitute the dried egg solids. In custards with the high concentration of egg, the additional milk was omitted. The dried egg custards were baked to the end internal temperature of 88, 90 and 92° C. in a 177° C. oven. Fresh egg control custards were baked to 88° C. A taste panel of 7 persons from the Foods and Nutrition Department evaluated the following palatability characteristics on a 7-point scale: color and texture of the crust, color, aroma, flavor, texture, and consist- ency of the body of the custard. Homogenization favorably affected the palatabil- ity of DWES custards. The non-homogenized variables were significantly different in crust texture from the fresh egg custards. The homogenized DWES custards, often described as tough and ”skin-like" on the surfaces, were not differ- ent from the control (1% level of probability). The crust color of the homogenized DWES custards was scored much higher than that of the non-homogenized DWES custards and slightly higher than that of the control which, in some cases, was noted as ”pale" and "anemic." The flavor and aroma of the homogenized DWES custards, though not as de- sirable as the flavor and aroma of the fresh egg custards, were more acceptable than those of the non-homogenized DWES custards. The texture of the body of DWES custards was improved by homOgenization. Particles of incompletely rehydrated dried egg were not present in the homogenized DWES custards but were evident in the non-homogenized DWES custards. The homogenized DWES custards were not signifi- cantly different from the controls. The fresh egg custard ranked highest in consistency. The firmness of the gel structure increased as the end internal baking temperature was raised from 88 to 90 to 92° C. The homogenized DWES custard baked to 92° C. was more firm while the homogenized DWES custard baked to 88° C. was less firm than the unho- mogenized DWES custards baked to the same temperature. The color of the body of the DWES custards was not significantly different from the fresh egg custards. Objective measurements indicated that the gel structure of the custards was greater when the high con- centration of egg was used. Of the custards baked to 92° 0., those receiving the homogenization treatment were usually more firm than those not undergoing the treatment. Homo- genized custards baked to 88° C. were less firm than the non-homogenized custards. Significant correlations were found between the consistency scores and all of the objec-. 'five readings. THE EFFECT OF HOMOGENIZATION ON THE GELATION AND PALATABILITY OF BAKED CUSTARDS PREPARED WITH DRIED WHOLE EGG SOLIDS By Marjorie Eleanor Mastic A THESIS Submitted to the College of Home Economics Michigan State University of Agriculture and ' Applied Science in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Foods and Nutrition 1959 ACKNOWLEDGEMENT The writer wishes to express her sincere grati- tude to Dr. Evelyn M. Jones for her guidance and interest throughout this study. Grateful acknowledgement is also due to Dr. L. E. Dawson, Associate Professor of Poultry Husbandry, Michi- gan State University, and to Dr. T. I. Hedrick, Professor of Dairy, Michigan State University, and his staff. With- out their invaluable assistance, a controlled study would not have been possible. The assistance of Dr. W. D. Baten, Professor of Statistics, Michigan State University, and Statistician, Agricultural Experiment Station, in the statistical analysis of the data is also greatly appreci- ated. The writer expresses her appreciation to Evelyn Appel, Norma Gilmore, Peggy McCullin, Sister Mary Romans McDermott, Lorraine Miller, Jeanne Sherburne, and Evelyn Wheeler who served on the taste panel. ii TABLE OF CONTENTS INTRODUCTION. . . . . . . . REVIEW OF LITERATURE. . . . History. 0 O O O O I O 0 General Method of Processing Methods of Drying Eggs . Belt-drying c c o o o Pfl‘dryingc c o c c c Spray-drying. . . . . Stability of Dried Whole Egg Solids. Decrease in dispersibility. Browning reaction . . Flavor changes. . . . Methods of Stabilizing . Acidification . . . . Glucose removal . . . Fermentation . . . Enzyme treatment . Inert gas packing . . Low-moisture content. Low-temperature storage iii Page mmdqmmemw +4 i4 +4 +4 .4 +4 +4 +4 +4 +4 as U1 \n -> e- wa \» xx +4 C) iv Heat Coagulation of Protein. . . . . . . . . . . Effect of acid. . Effect of alkali. Effect sugar . Effect salt. . Effect Effect the concentration the rate of Custards as a Medium for Egg Solids. . . . . Nutritive Value of Dried EXPERIMENTAL PROCEDURE. Design of Experiment Ingredients. . . . . Formula. . . . . . . Preparation. . . . . Subjective Tests . . Objective Tests. . . Micrometer Adjustment Curd Tension Meter. Per cent Sag. . . Statistical Methods. RESULTS AND DISCUSSION. Subjective Tests . . Color of the Crust. of protein. . . . cooking and temperature the Use of Dried Whole Whole Eggs. 0 O 0 0 O 0 O O O O O 0 Penetrometer. . . . . . O O O O O O O O O O O O Page 16 17 18 18 18 l9 19 20 23 26 26 26 28 3o 33 33 34 34 35 35 37 3s 3s Texture of the Crust. . . . . . . . Color of the Body of the Custard. . Aroma . . . . . . . . . . . . . . . Flavor. . . . . . . . . . . . . . . Texture of the Body of the Custard. Consistency . . . . . . . . . . . . Objective Tests. . . . . . . . . . . . Micrometer Adjustment Penetrometer. Curd Tension Meter. . . . . . . . . Per cent 33$. 1 O O O O O O O O O O 0 Correlation between Subjective Scores for Con- sistency and Objective Measurements . SUMMARY AND CONCLUSIONS . . . . . . . . . LITERATURE CITED. . . . . . . . . . . . . APPENDIX. . . . . . . . . . . . . . ... . Page 42 46 48 48 54 57 61 61 67 7O 73 76 80 84 Table 10 ll 12 13 14 LIST OF TABLES Formulas Used in the Preparation of Baked custards. O O O O O O O O O O O O O O O O O 0 Mean Scores for the Color of the Crust. . . . 2-Way Tables for the Color of the Crust of Baked Custards under Specific Experimental conditions. 0 O O O O O O O O O O O O O O O 0 Mean Scores for the Texture of the Crust. . . 2-Way Tables for the Texture of the Crust of Baked Custards under Specific Experimental conditions. 0 O O O O O O O O O O O O O O O 0 Mean Scores for the Color of the Body of the CuStard O O O O O O O O O O O O O O O O O O 0 Mean Scores for the Aroma . . . . . . . . . . 2-Way Tables for the Aroma of Baked Custards under Specific Experimental Conditions. . . . Mean Scores for the Flavor. . . . . . . . . . 2-Way Tables for the Flavor of Baked Custards under Specific Experimental Conditions. . . . Mean Scores for the Texture of the Body of the Custard . . . . . . . . . . . . . . . . . 2-Way Tables for the Texture of the Body of Baked Custards under Specific Experimental conditions. 0 O O O O O O O O O O O O O O O 0 Mean Scores for Consistency . . . . . . . . . 2-Way Tables for the Consistency of Baked Custards under Specific Experimental Con- ditions O O O O O O O O O O O O O O O O O O 0 vi Page 29 4O 41 45 44 47 49 5O 51 55 55 56 58 6O Table 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 3O vii Mean Penetrometer Readings on Baked Custards with the Crust On . . . . . . . . . . . . . . Mean Penetrometer Readings on Baked Custards with the Crust Off. . . . . . . . . . . . . . 2-Way Tables for the Penetrometer Readings on Baked Custards (Crust On) under Specific Experimental Conditions . . . . . . . . . . . 2-Way Tables for the Penetrometer Readings on Baked Custards (Crust Off) under Specific Experimental Conditions . . . . . . . . . . . Mean Curd Tension Meter Readings on Baked Gus-bards. O O O O O O O O O O O O O O O O l O 2—Way Tables for the Curd Tension Meter Read- ings of Baked Custards (Crust Off) under Specific Experimental Conditions. . . . . . . Mean Per cent Sag of Baked Custards . . . . . 2-Way Tables for the Per cent Sag of Baked Custards under Specific Experimental Con- ditions O O O O O O O O O O O O O O O 0 O O 0 Correlation between Subjective Scores for Consistency and Objective Measurements of Baked Custards. . . . . . . . . . . . . . . . Score Card for Baked Custards . . . . . . . . A Statistical Analysis of Consistency . . . . Studentized Multiple Range Comparison of Treatments at the 1% Level of Probability . . A Further Statistical Analysis of Consistency Studentized Multiple Range Comparison of Tem- peratures at the 1% Level of Probability. . . Procedure for Correction for Missing Value in Per cent Sag Calculations. . . . . . . . . Procedure for Calculation of Correlation coeffiCientso O I O O O O O O O O O O O O O O Page 62 63 64 65 68 69 71 72 75 85 86 87 89 91 92 INTRODUCTION In recent years, the demand for dried whole egg, yolk, and white increased sharply for use in com? mercial food products and in large quantity cooking. Work with the dried eggs, however, indicated that flavor and certain functional properties were altered during processing and storage. These changes limited the use of dried egg solids, as the quality of the foods in which they were incorporated was affected. One of the changes in functional properties was the decrease in dispersibility upon reconstitution. An objectionable characteristic observed in custards made with dried whole egg of decreased dispersibility was the formation of a thick, tannish-orange surface crust and a weakened gel structure (3). At Michigan State University, preliminary ex- perimental work in the preparation of custards made with dried whole egg solids indicated that homogenization of the custard mix gave a product acceptable in appearance and comparable to custards prepared with fresh shell eggs. The purpose of this study, therefore, was to determine the effect of homogenization on gelation and to compare the quality of baked custards made with 2 concentrations of dried whole egg solids and baked to 3 different end internal temperatures. REVIEW OF LITERATURE History The egg-drying industry began in the United States shortly after the turn of the century; but because a cheaper product was obtained from China, the industry did not grow. With the Japanese invasion of China and the enforcement of a new tariff in the 1930's, importations were cut; and the drying of eggs was stimulated in the United States (24). Only a small fraction of the total volume of eggs processed in the United States was dried before World War II. The amount varied from year to year, with the larger part being dried whites and dried yolks which were used in candies, noodles, and doughnut mixes (10). With the advent of war in Europe, the demand for dried whole eggs increased as it was realized that the concentrated product was a widely used and a highly nutritious protec- tive food. In addition, the dried eggs were easier and less expensive to handle since they took less storage space and weighed considerably less than packaged shell ease (19) . With the increased number of prepared mixes marketed in recent years, the demand for dried eggs be— came still greater. Rolfes, Clements, and Winter (26) stated that this demand would be even greater if various other food manufacturers could obtain equally good results. Extensive research was effective in extending the storage life of dried eggs and improving their palatability and functional performance by advances in methods of process- ing, facilities, equipment, and production standards (36). General Method of Processing A number of Operations are involved in the prep- aazation of dried whole egg, yolk, and white. The general procedure for the production of these products is summae- :flsed from several sources (10, 14, 29, 37). (a) Candling The fresh eggs are examined in a dark room for the presence of meat and blood spots. If spots are detected, the eggs are rejected. (b) Washing After candling, the shells of the eggs are washed when necessary with a detergent solution, followed by rinsing in a solution containing chlorine and then by fan-drying. (c) Breaking and separating The eggs are broken and yolks separated from whites if such treatment is planned. At this time any eggs having an off-odor are eliminated. Strict sanitation stand- ards are of utmost importance in the break- ing process. (d) Blending and homogenizing With blending or churning, smooth uniform products of yolks or whole eggs are obtained. Egg whites are not blended. Homogenizing completes the process of blending. The eggs are screened to remove any shell par- ticles or membranes. (e) Glucose removal In this process the whole eggs, yolks, and whites are desugared by enzyme action or fermentation. (f) Pasteurizing Flash pasteurizing of the desugared whole eggs and yolks aids in checking the bacteri- 'hJI growth. Desugared whites are not pas- teurized. (g) Acidification After pasteurization, dried whole egg sol- ids are acidified to a pH of 5.5 by the addition of hydrochloric acid. (h) Drying Dried whole egg and dried yolk are prepared by pumping the liquid egg into the spray drier under high pressure. Whites are pan- dried and occasionally spray-dried. (1) Packing Packing of dried egg in an atmosphere of 20% carbon dioxide and 80% nitrogen is rec- ommended. Methods of Drying Eggs Three commercial methods of drying eggs have been used in the United States. They include belt-drying, pan-drying, and spray-drying. The last 2 methods are much more important at the present time (24). Belt-dgyigg This commercial method, deveIOped early in the industry, was one in which the egg was poured onto metal belts about 4 feet wide and run through tunnels at low speed. Within the tunnels, heated air was circulated over the belt at 160° F. Mulvany (24) indicated that this method of drying was used to produce flaked yolk and flaked dried whole egg. Pan-drying Pan-drying is the method most used for the preparation of dried egg whites (19). In this method, a thin layer of stabilized liquid egg is placed on a tray or a shallow pan coated with wax or mineral oil. The pan is placed in a cabinet and warm air circulated over the eggs. The drying process takes 6 to 24 hours. The time is dependent on the temperature and air control in the cabinet. The dried egg white is flake-like and is re- ferred to as crystalline albumen. Powdered albumen is prepared by grinding and screening the flakes. Spray-drying Spray driers have been divided into 2 groups (10, 24). l) The tunnel or chamber type drier in which heated air passes through a chamber contain- ing nozzles from which the liquid egg is sprayed. 2) The cyclone type drier in which the egg is sprayed into a whirling current of air in a tower or similar structure. The operations involved in the processing of spray-dried eggs begin with a thorough mixing and strain- ing of the broken liquid egg. This is followed by heat- ing to 140° F. to improve the drying operation (19). The warm liquid egg, under a pressure of 2,000 to 6,000 pounds per square inch is sprayed from nozzles into a large drier chamber, through which a stream of air is passed at 250° to 300° F. The air picks up the moisture from the egg and leaves the chamber at 140° to 180° F. The temperature of the inlet air and the rate of flow of the liquid egg are adjusted to maintain the desired air outlet temperature. The egg powder settles in the bottom of the chamber from which it is withdrawn contin- uously (chamber or tunnel type drier), or it is in the exhaust air stream from which it is strained out (cyclone type drier) (10, 19, 24). The powder contains 4% to 5% moisture. If 3% or less moisture content is desired, the powder is brought in contact again with dry air at 140° F. to 220° F. until the proper level of moisture is reached (19). i The spray-drying method has been used in the preparation of dried whole egg solids and dried egg yolk. Dried egg white has been prepared only to a limited ex- tent by the spray-drying method. Lineweaver and Feeney (19) pointed out that because of the character of the white, lower temperatures and pressures are required. Stability of Dried Whole Egg Solids Eggs have been widely used in foods because of the many important functional properties they possess. As a result of the drying process and storage, an al- teration of some of these qualities occurred. This in- stability was one of the chief disadvantages of dried eggs. Decrease in dispersibility, the browning reaction, and flavor changes were properties of dried eggs which affected baked custards. A discussion of the functional properties affected by the processing and storage pro- cedures, the causes of these changes, and methods of prevention follow. Decrease i3 dispersib_iIi_t1 The quality of dried whole egg solids deteri- orated with imprOper processing and poor storage con- ditions. This physical deterioration was measured in terms of dispersibility (3). Both increases in tempera- ture of storage and water content influenced the rate 0f decrease of dispersibility (3, 20). A freshly prepared and carefully dried sample Wf dried egg remained homogeneous when reconstituted and I‘OS the 1/8 ing (20 con pre ten age 10 allowed to stand (3). Dried egg which underwent decrease in dispersibility due to overheating during drying or high temperature storage creamed on reconstitution and standing. Microscopic examination of the layer which rose to the tOp and was referred to as "cream” showed that some of the small fat globules from the yolk of the egg fused together and some of the larger globules con- tained air bubbles. An objectionable characteristic of custards prepared from dried eggs of decreased dispersi— bility was the formation of a tannish-orange surface crust, 1/8 to 1/4 inch thick, which was the result of the cream- ing of the egg solids on reconstitution (ll, 23). Lows (20) described this crust as a rubbery egg layer which could be lifted off practically intact from the custards prepared with dried eggs. Conrad et al.(lO) stated that acidification of liquid egg to a pH of 5.5 before drying favored the re- tention of dispersibility of a dried egg powder in stor- age. Browning reaction The browning or Maillard reaction in dried eggs was another undesirable change which took place in stor- age, and its occurrence was reported by several investi- «Sators (ll, 25). This reaction involved the aldehyde 11 group of glucose, naturally present in the eggs, and the free amino group of proteins (25, 28, 36). The rate of browning was influenced greatly by the temperature and length of storage, the pH, and the moisture content (20). As the temperature and length of time of storage were increased, the browning was greater. In addition, an increase in alkalinity speeded the brown- ing reaction. Browning occurred more rapidly in a moist product than in a dry product. Lineweaver and Feeney (19) indicated that glu- cose removal and acidification were 2 methods by which the stability of dried whole egg solids and dried egg whites was increased. Flavor Chggges Flavor changes were reported by several experi- menters (3. 4. 11) in their work with dried egg solids which made them unsatisfactory for use in straight egg dishes. Hawthorne (15) stated that samples with high- moisture content tended to deteriorate in flavor more rapidly during storage than those with low-moisture OOH? tent. In a later study, Bate-Smith, Brooks, and Hawthorne (3) pointed out that the rate of flavor deterioration ‘Ias a function of the storage temperature and water content. 12 The deterioration of dried eggs was rapid at high temper- atures and as water content increased, flavor changes were detectable at lower storage temperatures. Palatability was also affected by an increase in the length of storage time as reported by Paul et al. (25). The different types of off-flavors have been described as follows (3): Storage - This was the flavor developed at mod- erate temperatures of storage (15° 0.). It has often been described as ”cardboard". "Burnt" - This flavor resulted from high-temp perature storage or overheating during drying. The burnt or carmelized flavor has been described as ”biscuit“. ”Fishy" - Low moisture content samples stored at 15° C. for long periods developed a "fishy“ flavor. "Acid" or "Cheesy" - This flavor was developed in samples which had a low pH after recon- stitution. The texture of the product was grainy. Other - The development of other flavors was due to storage in non-air tight containers near strong smelling materials. 13 These flavor changes were generally due to high- temperature deterioration or non-oxidative changes and to oxidative changes in the phospholipid fraction of the eggs (3). The preparation of dried eggs of lowbmoisture content, the packaging of the dried eggs in containers from which all oxygen has been excluded, and storage at low temperatures were recommended as ways to control fla- vor changes (10). Methods of Stabilizing Acidificgtion The browning or Naillard reaction in dried eggs was minimized by the acidification process prior to dry- ing. After pasteurization, liquid whole egg was acidi- fied with hydrochloric acid to a pH of 5.5 and dried to a low level of moisture content. Sodium bicarbonate, approximately 1.5 pounds per 100 pounds dried egg solids, was mixed in with the dried product so that upon recoup stitution, the acid was neutralized (28, 36). Glucose removal By the removal of the naturally occurring glu- cose from.the egg, a more stable product was produced. l4 Fermentation and enzyme treatment were 2 methods of de- sugaring used. Fermentation Formerly egg whites were desugared by spontap nuns fermentation. This was an uncontrolled type of fer- mentation with the length of time of fermentation depen— dent on the temperature and the type of organism at work. (24). Odors and the proteolysis evident in the later stages of fermentation and the presence of the Salmonella organism made this method objectionable (2). Baker's yeast and various micro-organisms were employed in the desugaring process of egg whites and whole eggs, also. Enzyme treatment Approximately 10 years ago enzyme treatment was introduced. It was found to speed up the desugaring process considerably (25, 27). Snyder (27) reported that glucose oxidase was one enzyme accepted unanimously by egg dryers. This enzyme catalyzed the reaction by which glucose was converted to gluconic acid in the presence of excess oxygen. The source of the oxygen was hydrogen peroxide, from which it was released by the enzyme, cata- lase, present in the commercial preparation of glucose oxidase. After adjustment of the pH to 7.0 - 7.5 by the addition of hydrochloric acid, the egg white was heated 15 to 85° to 90° F. While held at that temperature, the enzyme preparation was added, followed by the continuous addition of hydrogen peroxide over a period of 7 hours. When all the glucose was converted, the egg white was dried. Enzyme activity was terminated by the drying proc- ess.. The same process, with minor adaptions, was used for the desugaring of whole eggs and yolks. Adjust- ment of the pH was not required. The egg was heated to a slightly higher temperature (100° F.), and a larger amount of the enzyme was used. 1193;: gag packigg To prevent or lessen deterioration in storage due to oxidation, the egg solids were cooled immediately and put into cans. The cans were vacuumized and gased with a mixture of 20% carbon dioxide and 80% nitrogen. The carbon dioxide aided the stabilization of the flavor of the eggs while the nitrogen minimized the vacuum dam- age to the cans. 6 Egg-moisture content Another method of retarding deterioration of dried eggs was by low-moisture content, but this has not been completely effective in itself (30). Hawthorne (5) stated that there was no critical moisture content below 16 which deterioration would not occur. Since low-moisture dried egg powders have a longer shelf-life, the trend today has been to produce powders with a moisture content of 2 to 4%. ngetemperature stcrgge Dried whole eggs became less "soluble" at the higher storage temperatures; and consequently, dispersi- bility was decreased (22). Jacobs (16) indicated that 50° F. was the maximum temperature at which whole egg should be stored for any length of time, even when the dried egg had a moisture content of 5% or less. Below 40° F. the changes were slowed; and at 0° F., they were practically eliminated. Thistle, White, Reid, and Wood- cock (30) reported objective tests of quality indicated that even at temperatures as low as -40° C. egg powder deteriorated slowly. Heat Coagulation of Protein Although protein may be coagulated by many means, heat has been one of the more important methods. Weiser (33) stated that heat coagulation of protein occurred in 3 distinct processes. The first reaction, denatura- ticn, was an intramolecular rearrangement (33) or an 17 opening up of the protein molecule (20), whereby certain chemical groups not detectable in the native protein be- came evident in the modified product. The second process was the flocculation of the denatured molecules, followed by the formation of an insoluble coagulum from the floc- culated mass, the third process. In custards, the largest amount of heat coag- ulable protein is furnished by the egg. Only 0.75% of) the heat coagulable protein is provided by the milk. Many factors affect the coagulation of protein and the gelation temperature of the custards. These factors in- clude the pH of the mixture, the proportion of ingredi- ents, and the rate of cooking. As a result, no one end baking temperature can be recommended as the optimum tem- perature to which a custard should be baked. Effect 9; A_c_i_d_ Weiser (33) indicated that certain protein sols coagulated at a definite temperature which was fairly constant for each protein. With the lowering of the pH by the addition of acid, the coagulation temperature was raised. Chick and Martin (8) pointed out that denatura- tion, the first part of the heat coagulation process, was not hastened by acid solution, but the clotting or coag- ulation process was speeded. 18 Effect gf_Alkali Chick and Martin (9) found that the second part of the coapflation process, the clotting or coagulation, did not occur in alkaline solution. They pointed out that if, after heating, the alkali was neutralized with acid, the coagulation process occurred. Effect gfb§gg§g The addition of sugar to egg protein raised the gelation temperature due to the peptization of the protein by the sugar. Lows (20) concluded that this ef- fect was directly proportional to the amount of sugar added. Effect 2;,Salt Salts or electrolytes greatly influenced the behavior of protein. Coagulation was brought about by adsorption of an ion having a charge opposite that of the protein to which it was attracted (20, 33). The amount of ion needed was dependent on the concentration of the colloid, the concentration of the salt, and the valence of that ion. The effect of the concentration of the salt and the valence of the ion on the coagulation temperature was demonstrated in baked custards (20). In general, the amount of salt necessary to produce flocculation varied with the valence of the ion. The greater the valence of 19 of an ion, the more effective was its coagulation power; and the more effective an ion was in its coagulating power, the less amount of that ion needed to bring about flocculation. Effect 9;; 1133 Concentrgm _o_f_ Protein Lows (20) stated that as the amount of protein increased, the temperature of gelation decreased. The lowering of the temperature was inversely proportional to the quantity of egg added. Lowe (20) reported that the rate of coagulation increased as the temperature was raised. In addition, a firmer custard was obtained as the temperature increased until at a specific temperature, dependent on the rate of cooking, Optimum gelation occurred. Further heating to a higher temperature caused porosity and finally syn- eresis. Experimentation showed that the rate at which custard was cooked affected the gelation temperature (20). With a slow rate of cooking, gelation of custard occurred at a lower temperature, while gelation took place at a higher temperature with a fast rate of cooking. A slower rate of cooking was considered most desirable because optimum gelation was more easily perceptible. Cu 81' pl“ (11 1‘8 pr per of 31‘ 20 Custards as a Medium for the Use of Dried Whole Egg Solids The use of dried eggs depends on how well they retain the properties that make fresh eggs useful in cook- ery. Thickening power is one of the important functional properties of the egg and is closely associated with the dispersibility of the dried egg. Since the baked custard represents a type of cooked product in which egg is a principal ingredient and one in which the thickening prop- erty of the egg protein is used, it can be used to com- pare the gelation properties of dried and fresh eggs. Color, flavor, and odor are also detected easily in the custards as they are made of relatively few essential ingredients. The quality of the dried eggs greatly affects the product in which they are used. Bate-Smith, Brooks, and Hawthorne (3) indicated that dispersibility could be used as a measure of quality. With deterioration, there is a decrease in the dispersibility of the dried egg which in turn affects the product. Ary and Jordan (1) found a slower rate of heat penetration in baked custards prepared with dried eggs of low dispersibility than in those in which fresh eggs or dried eggs known to have a higher degree of dispersibility 21 were used. The rate of rise in temperature was similar in custards prepared with fresh and dried egg until the temperature was reached at which the coagulation of egg protein began (68° to 70° C.). A possible factor respon- sible for the slowing down of heat penetration in the custards prepared with dried eggs of decreased dispersi- bility was the interference contributed by many small particles of incompletely rehydrated egg present in the gel structure. The firmness of the gel structure is dependent in part on the quality of the dried eggs. Dawson, Shank, Lynn, and Wood (11) observed that freshly dehydrated eggs produced custards which were smooth and firm, while dried eggs which had rapidly deteriorated due to adverse stor- age conditions gave custards which were soft and watery in consistency. Jordan and Sisson (18) reported dried egg custards were firm enough to be of a desirable con- sistency but not as firm as fresh egg custards. Ary and Jordan (1) stressed that a less firm custard may be asso- ciated with a powder of reduced dispersibility. The firmness of the gel structure also depends on the end internal baking temperature. No one specific temperature has been recommended due to variations in proportions of ingredients and the rate of cooking. Lows (20) stated that custards have a serving consistency between 82 00 CE tc ir WE 22 82° to 84° C. if cooked at ordinary rates. Curdling may occur at 85° to 87° C. under similar cooking conditions. With a more rapid rate Of heating, the custard may be heated to a higher temperature of 89° C. before curdling may be evident. Carr and Trout (7) found that the rate of heat penetration was slower in custards made with homogenized milk than in those made with unhomogenized milk. The firmness of the custards indicated that the custards pre- pared with homogenized milk could be baked to a higher end internal temperature without seriously affecting the stability of the gel. Miller, Jones, and Aldrich (23) observed that the Optimum gelation temperature of custards prepared from fresh shell, homogenized frozen, and blended frozen eggs with homogenized milk was 86° to 88° 0., while custards prepared with dried whole egg solids and baked to the same temperatures were less firm. Their study indicated that a higher end internal baking temperature was desirable for custards made with dried whole egg solids. Several experimenters (ll, 23) reported the formation of a thick, tannish-orange surface crust Of undesirable texture in custards prepared with dried eggs. This crust formation was directly related to the decrease in dispersibility of the dried egg solids. Miller, Jones, 23 and Aldrich (23) suggested that a longer period Of rehy- dration might reduce the thickness of the crust and, con- sequently, improve the texture. Unpleasant changes in flavor became evident as the dried egg powder underwent deterioration. Bennion, Hawthorne, and Bate—Smith (4) reported that the unpleas- ant flavor made dried eggs undesirable for straight egg dishes, which included baked custards, but could be used satisfactorily in sponge cakes. Ary and Jordan (1) simi- larly found that the undesirable flavor of dried egg powb ders of decreased dispersibility was more objectionable in baked custards than in plain cakes. Dawson, Shank, Lynn, and Wood (11) pointed out that storage temperature was very important in the retention Of flavor. Even after 1 year of storage at temperatures below 60° F., good fla- vor was retained. Jordan and Sisson (18) reported that custards made from dried eggs reconstituted by contact with water for 18 hours were nearly comparable in flavor to fresh egg custards. The study by Miller, Jones, and Aldrich (23) indicated that off-flavor was quite evident in custards prepared with dried egg solids. Nutritive Value of Dried Whole Eggs Since dried eggs completely replaced fresh shell 24 eggs in certain foods, the nutritive value of the dried eggs was of concern. Good quality dried whole eggs were found to have about the same food value as shell eggs if prOperly stored (31). They contained iron and the protein was of good quality. Several experimenters (5, 10, 35) studied the stability of the important vitamins in dried eggs. During the dehydration process, Whitford et al.(35) reported no destruction of vitamin A, thiamin, or riboflavin. With storage there was an appreciable decrease in vitamin A content, with the amount lost dependent on the length and the temperature of storage. Conrad et al.(10) pointed out that the loss of vitamin A was probably due to oxi- dation which could be prevented by storing in an inert gas atmosphere. Work by Bohren and Hauge (5) tended to confirm this theory. Considerable thiamine was destroyed upon storage but to a lesser degree than vitamin A. It was shown that reduction of the moisture content or acid- ification increased the stability of thiamine (10). Ribo- flavin and pantothenic acid were very stable in storage D (12). In view of these findings, dried eggs were con— sidered a good source of riboflavin and pantothenic acid. 25 If properly handled, they also supplied thiamine and vi- tamin A in appreciable quantities (35). EXPERIMENTAL PROCEDURE Design of Experiment Subjective and Objective evaluations were con- ducted on baked custards prepared with spray-dried whole egg solids and with fresh shell eggs which served as the control. Two concentrations of dried egg solids were used. The dried egg custards were baked to the and internal temperatures of 88° 0., 90° 0., and 92° 0. in a 177° 0. even. The fresh egg custard was baked to an end internal temperature of 88° C. The variables of dried egg custard mix received 2 treatments: homogenization and nonphomogenization. Four variables and a control were prepared each baking day. Six replications of each dried egg variable were baked. An entire replication of each variable, OOH! sisting of 20 custards, was baked at one time and included 7 custards for the subjective tests and 8 for the Objec- tive tests and 1 for the temperature reading. Ingredients Dried whole egg solids (DWES) from a common 26 27 lot were used in the preparation of the custards. The whole egg solids were prepared commercially. They were enzymatically desugared by glucose oxidase with hydrogen peroxide and spray-dried to a moisture content of 2 to 4% in a Gray-Jensen dryer with air outlet temperature of 74° C. The DWES were cooled immediately to 46° 0., packed in drums (July 19, 1957), and held at 7° 0. After overnight shipment from the processing plant, the egg solids were stored again at 7° 0., hermetically sealed in a nitrogen atmosphere in 3-pound tin cans, and shipped to Michigan State University (November 4, 1957) where they were refrigerated immediately at 5° C. The DWES were 18 to 20 months Old when used in this study. Fresh eggs for the control custards were obtained from a specific flock of White Leghorn hens at the Michi- gan State University Poultry Farm. The eggs were stored under refrigeration at the Poultry Building and were 2 days old when used. Freshly processed homogenized milk was obtained in a large lot from the Michigan State University Dairy on the day preceding each baking day and was stored at 5° 0. in a walk-in refrigerator. I The granulated sugar was from a common lot of best sugar. 28 Formula The weights of ingredients used in the prepay :nfldon of the control custards and the custards prepared from the 2 concentrations of DWES are found in Table l. The formula for the fresh egg custard was based on the recipe in Lowe's text (20) with one change; namely, the amount of sugar was increased to 2% tablespoons per cup of milk. The weight of DWES substituted for the shell eggs was based on the fact that the raw whole egg contained 74% water and 26% solids (32). One concentration of DWES used in the preparation of custards was equal to the weight of the solids content of the fresh eggs in the formula for control custard. The weights of sugar and milk re- mained the same as those used in the control custard. For the purpose Of simplification, the concentration of dried egg in these custards was designated as a high con- centration. In the custards made with the second concen- tration of DWES, the milk was increased by an amount equiv- alent in weight to the water necessary for reconstitution of the egg solids. The weights Of the dried egg and the sugar remained the same. This concentration of egg solids was designated as a low concentration. 29 TABLE 1 Formulas Used in the Preparation of Baked Custards Ingredients Fresh Dried Egg Custards Cugéird High Egg Low Egg Concentration* Concentration gm. gm. gm. Milk 2440 2440 2791 Egg - Fresh 480 -- -- - Dried -- 129 129 Sugar 312 312 312 Salt ' 2 2 2 * Amounts Of ingredients were increased one-tenth when mix was homogenized. 30 Preparation The day preceding the preparation Of the cus- tards, the sugar, salt, and DWES were weighed into con- tainers on a Toledo direct reading scale and tightly cov- ered with Saran wrap. The DWES were refrigerated at 6° 0. The homogenized milk was weighed out as needed for preparation and heated to 27° C. in the top of a large double boiler. In the preparation Of the DWES custards, 1 cup of milk was removed from the double boiler. The entire amount of sugar was added to the remaining milk and dissolved by an initial stirring for 1% minutes and five l5-second stirrings at intervals. Meanwhile, the cup of milk was added to the dried eggs and blended for 15 minutes by a Kitchen Aid mixer, model K5-A, with a whip attachment on speed 1 to form a paste. After 2 and 4 minutes, the mixer was stopped and the unmoistened DWES were scraped from the sides and bottom of the mixing bowl with a rubber scraper. At the end Of the 15-minute blend- ing period, the sugar-milk mixture was added in 2 equal portions. Each was blended with the dried-egg-milk mix- ture at speed 1 for 5 minutes. The custard was poured through a #18 mesh strainer to separate out any large particles of dried egg. 31 Homogenization of the custard mix was done at the Michigan State University Dairy Plant in Anthony Hall in a laboratory homogenizer with a single stage process at a pressure of 2,000 to 2,500 pounds per square inch. The custard mixes were transported in large glass jars, transferred to stainless steel containers at the Dairy Plant, and warmed to 54.4° 0. (130° F.) in a running hot water bath. After homogenization, the mix was cooled to 26.7° C. (80° F.) in a running cold water bath and returned to the Food's laboratory and baked immediately. The homogenized DWES custards were the first 2 variables baked on any given day. For the fresh egg custards, the sugar was added to the entire quantity of milk and similarly dissolved by an initial stirring for 1% minutes and five lS-second periodic stirrings. During this time 11 shell eggs were broken out and blended on a Kitchen Aid Mixer, model K3—0, for 6 minutes at speed 1 with a whip attachment. The eggs were weighed into a mixing bowl and the milk-sugar mixture added and blended on the Kitchen Aid mixer, model K5-A, for 6 minutes at speed 1. The custard mix was then strained. The custards were baked in 5-ounce pyrex cus- tard cups. Each cup was filled with custard mix to a measured depth of 1 3/4 inches. The cups, divided into 32 5 coded groups and numbered from 1 through 20, were placed in numerical order in a large stainless steel baking pan which contained a layer of screening to hold the cups off the bottom of the pan. The baking pan was placed on a rack 3 inches from.the bottom of a gas oven preheated to 177° 0. Water at room temperature (25° - 27° 0.) was poured into the baking pan until it came up to the level of the custard mix in the cups. Three lead wires from a Brown Electronik Potentiometer High Speed multiple Point Recorder were sus- pended by means of clamps from the upper rack of the oven. The tip of one of these lead wires was centered in a cus- tard in a central position in the baking pan. A second wire was placed in the water bath while the third wire was suspended freely in the oven. Time-temperature read- ings were Obtained from the recordings made by the poten- tiometer during the baking of the custards. Readings were taken every 5 minutes for the first 50 minutes of baking, every 2 minutes for the next 10 minutes of baking, and every minute thereafter until the custards reached the desired internal temperature. Upon completion of baking, the custards were removed from the water bath, placed on a wire rack, and allowed to cool at room temperature for at least 1% hours 33 before covering with aluminum foil for refrigerator stor- age. Subjective Tests All custards were randomized with regard to baking position for the subjective tests. The custards were covered individually with aluminum foil to prevent any intermingling of odors and were refrigerated at 6° C. until evaluated during the morning following the baking. The panel, composed of 7 judges from the Foods and Nutri- tion Department of Michigan State University, evaluated the cold custards on the following characteristics: color and texture of the crust, color, aroma, flavor, texture, and consistency Of the body of the custard. A 7-point scale was used in the evaluation with 7 as the highest score. The judges were asked to record comments with regard to any outstanding features noted. A sample of the score card used in the subjection evaluation is in Table 24 of the appendix. Objective Tests All samples were randomized for the Objective 34 tests and were stored 19 to 22 hours at a refrigerator temperature of 5° 0. before the tests were made on the cold custards. Micrometer Agjgstment Penetrometer The firmness of the baked custards was deter- mined by use of the Micrometer Adjustment Penetrometer. The custard cup was placed on a level platform directly beneath the cone attachment, with the point of the cone just touching the surface of the custard. The cone was released and a reading taken at the end of 5 seconds. The depth in millimeters to which the cone and rod (150 gram weight) penetrated the baked custard was considered a measurement of the firmness. Duplicate readings were taken on samples of all variables from which the crust was carefully removed and those from which the crust was not removed but loosened from the edges of the cup. As the reading increased, the amount of penetration was greater. This indicated a decrease in the firmness Of the gel structure of the custard. 295; Tension £9.19}: The Raytheon Curd Tension Meter (model number 2-505) was used to measure the firmness of the custards. Duplicate readings were taken on samples of all variables from which the crust was removed. The custard cup was 35 placed on the platform of the instrument, directly beneath the cutting blade. The motor-driven blade was then low- ered into the custard. The resistance Offered the blade in passing through the custard was determined by the amount the float was raised out of the column of mercury. The measurements were obtained directly from a scale calibrated in grams. 22222212113 The firmness of custards was also determined by measurements for the calculation of per cent sag. The height of the baked custard was measured to the nearest 1/32 inch by means Of a depth gauge inserted into the center of the custard while it remained in the cup. The custard was then loosened carefully with a metal spatula and inverted on a glassplate. After 15 minutes the height was determined again by inserting the depth gauge into the center of the custard. The difference between the 2 readings divided by the original measured height and multiplied by 100 gave the per cent sag. Statistical Methods The data Obtained from the subjective and ob- jective tests on the baked custard variables were evaluated 36 by F tests for the analysis Of variance. When signifi- cant differences due to the treatments were found, the mean scores for the variables on which the tests were made were compared using the studentized multiple ranges. Correlation coefficients were calculated on the following pairs of items: consistency vs. curd tension meter readings (crust Off); consistency vs. penetrometer readings (crust on); consistency vs. pene- trometer readings (crust Off); and consistency vs. per cent sag (inverted). RESULTS AND DISCUSSION The quality of baked custards prepared from homogenized and non-homogenized custard mix containing 2 concentrations of DWES, baked to the end internal tem- perature Of 88° 0., 90° 0., and 92° C. were evaluated by subjective and Objective tests. The scores obtained from these tests were analyzed by an analysis of variance and by the studentized multiple range (13) when signifi- cant differences were found. The mean taste panel scores and Objective test readings for each replication of the baked custards variables and 2-way tables listing the mean scores of the custard. under experimental conditions of treatments, temperatures, and concentrations Ofegg solids are given in tables accompanying the discussion of the results Obtained for each of the quality factors. An illustration of the analysis of variance and student- ized range calculations for one of the quality factors are found in the appendix, on pages 86 to 90. The formula used in the correction for the 1 missing value in the per cent sag calculations is shown in Table 29 on page 91 of the appendix. 37 38 Subjective Tests Color 2; the Crust The mean scores for the color of the crust are listed in Table 2. The source of variation among the scores as indicated by the analysis of variance from which the scores of the control were excluded was the homogeni- zation treatments. In the 2-way tables in Table 3 are given the mean scores of the experimental treatments, temperatures, and concentrations of egg for the samples of baked cus- tards. Comparison Of the treatments by the studentized multiple range method showed that the homogenized DWES custards and the non-homogenized DWES custards were sig- nificantly different from the fresh egg custard and from each other. Baked custards made from the homogenized mixes received higher mean scores than custards prepared from the non-homogenized mixes, irrespective Of the concentra- tion Of the dried egg. Fresh egg custards had a mean score between those of the homogenized and non-homogenized samples. The crusts Of the non-homogenized DWES custards were an Off-color (bright yellow to orange). This Key: Variable 1 10 11 12 13 39 Homogenized DWES custards, high egg concentration, baked to 88° C. Homogenized DWES custards, high egg concentration, baked to 90° 0. Homogenized DWES custards, high egg concentration, baked to 92° C. Homogenized DWES custards, low egg concentration, baked Homogenized DWES custards, low concentration, baked Homogenized DWES custards, low concentration, baked Non-homogenized DWES concentration, baked Non-homogenized DWES concentration, baked Non-homogenized DWES concentration, baked Non-homogenized DWES concentration, baked Non-homogenized DWES concentration, baked Non—homogenized DWES concentration, baked to 88° C. to 90° 0. to 92° 0. custards, to 88° 0. custards, to 90° C. custards, to 92° 0. custards, to 88° 0. custards, to 90° 0. custards, to 92° 0. 98% egg high 663 high egg high egg low egg low egg low egg Fresh egg custard (control), baked to 88° C. 40 TABLE 2 Mean Scores for the Color of the Crust Vari- Replications Mean able 1 2 3 4 5 6 11 5.72 5.4 5.4 5.3 5.3 5.9 5.50 2 5.6 6.0 5.3 5.1 5.4 5.3 5.45 3 5.4 5.4 5.3 5.6 5.6 5.2 5.42 4 5.6 5.7 5.7 5.3 5.6 5.3 5.53 5 4.7 5.3 5.6 5.6 5.4 5.3 5.32 6 5.9 5.7 5.3 5.0 5.4 5.6 5.48 7 3.6 3.6 3.9 3.4 4.0 3.9 3.73 a 3.7 3.9 2.4 3.7 3.4 3.1 3.37 9 3.7 3.9 3.3 3.3 3.6 4.0 3.63 10 3.3 4.0 3.7 3.4 3.3 3.9 3.60 11 2.9 3.9 4.0 3.9 3.3 3.3 3.55 12 4.4 3.1 3.0 3.6 3.1 3.4 3.43 13 4.2 4.3 4.7 5.0 4.8 5.0 4.67 1 Refer to the key for variables on page 39. 2 Mean score of 7 judges' evaluationsof 1 replication Of each variable. 41 TABLE 3 2-Way Tables for the Color Of the Crust of Baked Custards under Specific Experimental Conditions Treatments Temperatures Treatment Means** 88° C. 90° C. 92° C. Homogenization 66.2 64.6 65.4 5.5 Non-homogenization 44.0 41.5 42.4 3.6 ** The homogenization and non-homogenization treatments of DWES custards were significantly different from each other at the 1% level of probability. Temperatures DWES Concentrations Temperature Means High Egg Conc. Low Egg Conc. 88° C. 55.4 54.8 4.6 906 c. 52.9 53.2 4.4 926 c. 54.3 53.5 4.5 Concentrations _r_ Tfi°tm°nt° HomOgeni- Non-homo- Concentration zation genization Means High Egg Concen- tration 98.2 64.4 4.5 Low Egg Concen- tration 98.0 63.5 4.5 - . - - .. - u c o—. 4 sun-on.- 9 o ,,- . 1 4 .2 . o . . .4- v - . _ .. - . - . O . . --E - «o - — - - - 4 v 2 .... ~ . ' - - 1 r - e -- - us . - .. , , p . 4 . . -- 4 - ‘ - o , 1 ‘ - . .. v . . . 42 Objectionable, intense color accounted for the low scores assigned the custards. The homogenized DWES custards had crusts of a lighter yellow. A slight gray cast was evident in the color of these samples also. The taste panel considered the crust Of the fresh egg custard ”pale" and "anemic" in some cases. Browning was apparent frequently on the custards baked to 92° 0. and occasionally on those baked to 90° 0. Texture 2; Q3 g_r_q_s_t ‘ The mean scores for the texture of the crust of the custards are presented in Table 4. The analysis of variance of the scores from which those of the control were excluded and the studentized multiple range showed significant differences in the joint effect of the treat- ments and concentrationson.the crust texture. Variation due to replications was not significant. Table 5 includes the mean scores for this quality factor under the experi- mental conditions. . The fresh egg custards had the highest mean score for the texture of the crust and were considered the most acceptable. The scores for the texture of the crust of all the non-homogenized DWES custards were sig- nificant from the control at the 5% and 1% levels of prob- alrility. At the 1% level, all the non-homogenized DWES 43 TABLE 4 Mean Scores for the Texture of the Crust Vari- Replications Mean able 1 2 3 4 5 6 11 4.02 4.0 4.7 4.3 5.3 4.9 4.53 2 5.0 4.3 4.6 5.1 4.4 4.4 4.63 3 4.0 4.7 4.9 4.7 5.0 4.0 4.55 4 4.1 4.4 3.4 4.6 4.6 4.7 4.30 5 4.0 3.4 4.9 4.7 4.7 4.1 4.30 6 4.6 4.3 4.7 3.7 4.6 4.6 4.42 7 3.9 2.9 4.0 3.0 3.6 3.4 3.47 8 4.0 3.4 1.9 3.7 3.0 3.3 3.22 9 3.1 3.0 2.3 3.4 3.6 3.3 3.12 10 3.6 3.3 3.4 3.0 3.1 4.0 3.40 11 3.1 3.1 3.1 3.3 3.4 3.4 3.23 12 4.6 3.4 2.9 3.9 3.9 3.9 3.77 13 4.1 4.6 4.4 5.1 4.9 4.9 4.67 1 Refer to the key for variables on page 39. 2 Mean score of 7 judges' evaluations of l replication Of each variable. 44 TABLE 5 2-Way Tables for the Texture of the Crust of Baked Custards under Specific Experimental Conditions Treatments Temperatures Treatment ileans 88° 0. 90° 0. 92° 0. Homogenization 53.0 53.6 53.8 4.5 Non-homogeniza- tion 41.2 38.7 41.3 3.4 Temperatures DWES Concentrations Temperature Means High Egg Conc. Low Egg Conc. 88° 0. 48.0 46.2 3.9 906 0. 47.1 45.2 3.8 92° C. 46.0 49.1 4.0 Concentrations Treatments Concentration Means Homogeni- Non-homogeni- zation zation_ High Egg Con- centration 82.3 58.8 3.9 Low Egg Con- centration 78.1 62.4 3.9 - s—AA .1 e . —.' F- e 0 .fi- 0...-”- s \4 . -v- h--. 45 custards except that variable containing the low concen- tration of dried egg and baked to 92° C. were significantly different from all samples of homogenized DWES custards with regard to the texture of the crust. The homogenized DWES custards and the fresh egg custards were not signi- ficantly different from each other. The fresh egg custard was scored the highest in texture of the crust. The 3 homogenized DWES custard variables Of high egg concentration were judged next high- est, followed by the 3 homogenized DWES custard variables of low egg concentration. The judges indicated that the crusts of the homogenized DWES custards were tough and formed "skin-like" surfaces. The crust of the non-homogenized DWES custards did not have a desirable texture. The taste panel noted that the crusts of these custards were thick, grainy, and porous. It was evident that incompletely rehydrated egg suspended in the custard mix contributed to the thickness and intensity of the color of the crust. These particles of egg rose slowly to the surface until the gelation tem- perature of the custard was reached. Variation in the texture of the crust was apparent within any one replica- tion of the non-homogenized DWES custards. This variation was due to the differences in the amounts of creamed egg solids each cup held. The first custard cups filled from 46 a container of the DWES custard mix tended to have a consid- erable amount of the creamed egg solids; and as a result, the crusts had a thick, moist, and extremely porous ap- pearance. Later custards poured from the same container of custard mix had a thick, grainy, and smoother crust as less “cream" was present. The homogenization process was a successful method whereby the texture of the crust of the DWES cus- tards.was altered to give an acceptable product. Possibly, the toughness associated with the crusts of the homogenized DWES custards may be explained in part by the greater dispersion of the fat globules in the DWES custard as a result of homogenization. 29.122 24. 12.1.2.4 air 9.2 ms ____Custard In Table 6 the mean scores for the color of the body of the custard are listed. An analysis Of vari- ance indicated no significant differences in the color Of the body of the fresh egg custards and the custards prepared with whole dried egg solids. This fact was at- tributed to the attempt made to use fresh eggs which gave a product comparable in body color to that of the dried egg custards in order to eliminate any bias in scoring by the taste panel. Variation due to replications was not significant. 47 TABLE 6 Mean Scores for the Color of the Body of the Custard Vari- Replications Mean able 1 2 3 4 5 6 11 5.72 5.9 5.0 5.1 5.7 5.4 5.47 2 5.7 5.6 5.6 5.6 5.0 5.3 5.47 3 5.7 5.7 5.6 5.4 5.3 5.4 5.52 4 5.3 5.6 6.0 5.3 5.0 5.1 5.38 5 5.1 a 5.3 5.7 5.4 5.4 5.4 5.38 6 5.6 5.7 5.0 5.7 5.7 5.6 5.55 7 5.6 4.9 5.4 5.4 5.6 5.4 5.38 8 5.7 5.4 5.4 5.1 5.1 5.4 5.35 9 5.7 5.3 5.1 5.4 5.4 5.9 5.47 10 5.1 5.3 5.1 5.0 5.1 5.4 5.17 11 5.1 5.7 5.1 5.4 5.3 5.4 5.33 12 5.9 4.7 5.4 4.9 5.3 5.4 5.27 13 5.3 5.0 5.1 5.4 5.3 5.3 5.23 1 Refer to the key for variables on page 39. 2 Mean score of 7 judges' evaluationsof l replication of each variable. .. v- cu...“ ge- - -9 ' -e 0‘---” “- -v.-.“ 48 Table 7 shows the mean scores for the aroma of the baked custards. The source of variation among the scores for aroma shown by the analysis of variance which included the scores of the control was due to the treatments at the 5% level of probability. Further analy- sis of the individual factors which comprised the treat- ments indicated no differences in aroma between the DWES custards. The difference existed between the 2 types of egg used. Table 8 lists the mean scores for the aroma Of the baked custards under the different experimental conditions. There were no significant differences between replications. The fresh egg custard received the highest mean score and was considered typical in aroma. By the stu- dentized multiple range method, the fresh egg custard scores were significantly higher than all other scores for the DWES custards except the homogenized DWES custards of both egg solid concentrations baked to 92° C. Aroma was a quality factor which was sometimes hard to evaluate. This difficulty was expressed by sev- eral members of the taste panel. Flavor Table 9 gives the mean scores for the flavor of the baked custards. Treatments accounted for the 49 TABLE 7 Mean Scores for the Aroma Vari- Replications Mean able 1 2 3 4 5 6 11 4.92 5.0 4.7 5.1 5.3 5.1 5.02 2 4.9 5.1 4.9 5.4 5.1 4.7 5.02 3 5.0 4.9 5.4 5.0 5.1 5.3 5.12 4 5.0 4.9 5.3 4.9 4.9 5.1 5.02 5 5.1 4.6 5.1 4.9 5.0 4.4 4.85 6 5.3 5.3 5.1 5.1 5.0 5.1 5.15 7 4.9 4.6 5.0 5.0 5.1 5.1 4.95 8 4.9 4.9 5.0 4.9 5.1 4.9 4.95 9 4.7 4.9 4.3 4.7 5.1 5.3 4.83 10 4.7 4.7 5.0 5.1 4.9 5.1 4.92 11 4.4 5.0 4.9 5.1 5.1 4.9 4.90 12 5.0 5.1 4.7 5.3 4.9 4.9 4.98 13 5.1 5.3 5.3 5.3 5.3 5.3 5.27 1 Refer to the key for variables on page 39. 2 Mean score of 7 judges' evaluationsof 1 replication of each variable. 50 TABLE 8 2-Way Tables for the Aroma Of Baked Custards under Specific Experimental Conditions Treatments Temperatures Treatment Means 88° C. 90° 0. 92° C. Homogenization 60.2 59.2 61.6 5.0 Non-homogeniza- tion 59.2 59.1 58.9 4.9 Temperatures DWES Concentrations. Temperature , Means High Egg Conc. Low Egg Conc. 88° C. 59.8 59.6 5.0 906 c. 59.8 58.5 ' 4.9 925 c. 59.7 60.8 5.0 Concentrations Treatments Concentration Means Homogeni- Non-homogeni- zation zation High Egg Con- centration 90.9 88.4 5.0 Low Egg Con- centration 90.1 88.8 5.0 D A -i~ s ,, - o ‘—- -v‘ TABLE 9 Mean Scores for the Flavor Vari- Replications Mean able 1 2 3 4 5 6 l1 4.42 4.1 4.0 3.7 3.4 4.4 4.00 2 5.0 4.4 4.9 4.7 3.9 4.6 4.58 3 4.9 5.4 4.9 4.3 5.1 4.6 4.87 4 4.6 4.3 5.0 4.0 3.1 4.6 4.27 5 3.9 4.3 4.6 4.4 4.1 3.7 4.17 6 5.3 4.7 4.0 4.0 5.0 5.3 4.72 7 5.0 4.3 5.1 4.4 4.9 4.4 4.68 8 4.6 4.9 4.0 4.4 4.7 4.9 4.58 9 4.9 4.3 4.9 4.4 4.7 5.3 4.75 10 4.0 4.9 4.3 4.6 4.7 4.6 4.52 11 4.9 4.7 4.6 4.9 4.3 4.6 4.67 12 4.7 4.9 4.3 5.0 4.6 4.6 4.68 13 5.4 5.4 5.3 5.4 5.6 5.7 5.47 1 Refer to the key for variables on page 39. 2 Mean score of 7 judges' evaluations of 1 replication of each variable. 52 variation in flavor as indicated by the analysis of vari- ance of the scores in which those of the control were included. Analysis of the individual factors involved in treatments to the DWES custards showed that the homo- genization and non-homogenization treatments and the tem- peratures to which the dried egg custards were baked were statistically different. Variation due to replications was not significant. Table 10 shows the mean scores of the baked custard variables in relation to treatments, temperatures, and concentrations of egg. The fresh egg custard was the most acceptable and had the highest mean score for flavor. It was con- sidered typical in flavor. All DWES custards were scored significantly lower than the control (studentized multiple range methods of comparison). At the 1% level, only one sample, the homogenized DWES custard of high egg concen- tration baked to 92° 0., did not vary significantly from the control. Nevertheless, this variable was not consid- ered typical by the taste panel. The "eggy" flavor evi- dent in the custards made with DWES was noted less fre- quently by the taste panel in those custards which had received the homogenization treatment. Those custards baked to the end internal tem- perature Of 92° C. were rated the highest of all the DWES 53 TABLE 10 2-Way Tables for the Flavor of Baked Custards under Specific Experimental Conditions Treatments Temperatures Treatment Means* 88° 0. 90° C. 92° 0. Homogenization 49.6 52.5 57.5 4.4 Non-homogeni- zation 55.2 55.5 56.6 4.6 * The homogenization and non-homogenization treatments of DWES custards were significantly different from each other at the 5% level of probability. Temperatures DWES Concentrations Temperature Means** High Egg Conc. Low Egg Conc. 88° 0. 52.1 52.7 4.4 906 c. 55.0 53.0 4.5 92: c. 57.7 56.4 4.8 ** All temperatures were significantly different from each other at the 1% level of probability. Treatments Concentrations Concentration Homogeni- Non-homogeni- Means zation zation High Egg Con- centration 80.7 84.1 4.6 Low Egg Con- centration 78.9 83.2 4.5 54 custards and were considered the most desirable in fla- vor. All of the custards contained the same amounts of sugar, but those baked to 88° C. appeared more sweet than those baked to 90° 0. and 926 0. Texture 9_f_ 1h; B2311 2; 1:23 Custard The mean scores for the texture of the body of the custard are given in Table 11. As determined by the analysis of variance, the variation of the scores from which the control was excluded was due to the inter- action between the treatments and the end internal tem- peratures to which the DWES custards were baked. Varia- tion due to replications was significant at the 5% level of probability. Possibly this was due to the differences in the amounts of incompletely rehydrated particles of dried egg which became trapped in the gel structure as it formed during the baking process. In addition, the taste panel's reaction to this effect on texture may be another source of the variation in replications. Mean scores of the experimental treatments, temperatures, and concentrations of egg protein for the custards are included in Table 12. As indicated by the mean scores, the homogenized DWES custards with high concentrations of egg solids baked to 90° C. and 92° 0. were judged the smoothest in texture. 55 TABLE 11 Mean Scores for the Texture of the Body of the Custard Vari- Replications Mean able 1 2 3 4 5 6 11 5.92 6.0 5.0 5.1 6.0 4.6 5.43 2 6.4 5.9 5.9 5.7 5.6 5.1 5.77 3 5.9 6.1 6.0 5.3 6.1 5.1 5.75 4 5.4 5.6 6.3 4.7 4.3 5.0 5.22 5 6.0 5.6 6.0 5.4 5.6 5.3 5.65 6 5.9 6.0 5.1 5.4 5.7 6.1 5.70 7 5.1 5.3 4.9 5.1 4.6 5.0 5.00 8 5.3 5.0 5.3 4.4 4.6 5.0 4.93 9 4.9 4.1 4.9 4.4 5.0 5.6 4.82 10 4.4 5.6 4.7 4.1 4.9 5.3 4.83 11 4.9 5.4 4.9 5.3 4.3 5.3 5.02 12 4.7 4.6 4.7 4.1 4.6 4.6 4.55 13 5.9 5.8 5.7 5.3 5.8 5.8 5.72 1 Refer to the key for variables on page 39. 2 Mean score of 7 judges' evaluations of l replication of each variable. 56 TABLE 12 2-Way Tables for the Texture of the Body of Baked Custards under Specific Experimental Conditions Treatments Temperatures Treatment Means 88° 0. 90° C. 92° C. Homogenization 63.9 68.5 68.7 5.6 Non-homogeniza- tion 59.0 59.7 56.2 4.9 Temperatures DWES Concentrations ' Temperature Means High Egg Conc. Low Egg Cone. 88° 0. 62.6 60.3 5.1 90° 0. 64.2 64.0 5.3 925 c. 63.4 61.5 5.2 Concentrations Treatments Concentration Means Homogeni- Non-homogeni- zation zation High Egg Concen- tration 101.7 88.5 5.3 Low Egg Concen- tration 99.4 86.4 5.2 57 The control ranked next in texture followed by the homo- genized DWES custards with low egg concentration baked to 92° 0. and 90° C. All non-homogenized DWES custards were scOred much lOwer. The poorer scores received by these custards was attributed in part to the yellow particles of incompletely rehydrated dried egg noted by the taste panel. The 2 non-homogenized DWES custards baked to 92° C. were scored the lowest. The taste panel described these variables frequently as porous. These results substan- tiate the inter-relationship of treatments and tempera- tures in this study. The extreme differences in texture scores for the non-homogenized and homogenized DWES custards is due to the homogenization treatment which resulted in a greater dispersion of the dried egg. It would appear that the homogenized custards could withstand a higher end inter- nal baking temperature before porousness was evident than could the non-homogenized custards. This thesis is in accord with the findings of Carr and Trout (7) in their work with custards made with homogenized milk. Consistency Table 13 shows the mean scores for the consist— :ency of the baked custards. An analysis of variance of the scores from which those of the control were e—U .. (J 58 TABLE 13 Mean Scores for Consistency Vari- Replications Mean able 1 2 3 4 5 6 11 5.02 5.0 3.3 3.6 4.9 2.7 4.08 2 5.7 5.0 5.6 5.0 5.3 5.9 5.42 3 5.6 5.4 5.7 5.1 5.6 5.6 5.50 4 5.4 4.3 5.4 2.4 3.7 3.3 4.08 5 4.4 5.6 4.9 4.1 5.0 5.3 4.88 6 5.9 5.9 3.3 5.3 5.6 5.7 5.28 7 5.4 4.0 5.6 5.1 5.3 4.9 5.05 8 5.6 5.1 5.1 5.3 5.3 5.1 5.25 9 5.3 4.7 5.1 5.1 5.0 5.4 5.10 10 3.4 4.9 4.0 4.0 4.6 5.4 4.38 11 5.4 5.1 5.1 4.7 5.0 5.4 5.12 12 5.1 5.4 5.4 5.4 5.6 5.1 5.33 13 5.4 5.6 6.0 5.9 6.0 6.0 .5.82 1 Refer to the key for variables on page 39. 2 Mean score of 7 judges' evaluations of l replication of each variable. 59 excluded indicated that the source of variation was the end temperature to which the custards were baked. Vari- ation due to replication was not significant. Table 14 gives in 2-way table form the mean scores for the custard variables as influenced by the experimental conditions. Taste panel evaluation showed that the consist- ency of the fresh egg custard baked to 88° C. was most preferred in firmness. Of the DWES custards, those cus- tards baked to 92° 0. received mean scores higher than those baked to 88° 0. and 90° 0. with the exception of the non-homOgenized custard containing the high concen- tration of dried egg baked to 92° 0. In the latter case, the non-homogenized DWES custards baked to 90° 0. was slightly preferred. Although the custards baked to 92° C. were occasionally described as too firm, their consisten- cies were more desirable than those Of the custards baked to the lower end internal temperatures. Custards prepared with the low concentration of egg and baked to 88° C. and 90° 0., were designated as being "too soft” more frequently than those custards containing the high concentration of egg and baked to the same end internal temperature. The concentration Of egg protein gave no statistical dif— ference in the firmness of the DWES custards. The analysis of variance Of the scores for all 60 TABLE 14 Mean Scores for the Consistency of Baked Custards under Specific Experimental Conditions Treatments Temperatures Treatment - Means 88° C. 90° 0. 92° 0. Homogenization 49.0 61.8 64.7 4.9 Non-homogenization 56.6 62.2 62.6 5.0 Temperatures DWES Concentrations Temperature Means** High Egg Conc. Low Egg Conc. 88° 0. 54.8 50.8 4.4 90° C. 64.0 60.0 5.2 92° C. 63.6 63.7 5.3 ** The 88° 0. temperature was significantly different at the 1%.level of probability from the 90° 0. and 92° C. temperatures. The 90° C. and 92° C. temperatures were not significantly different from each other. Concentrations Treatments Concentration Means Homogeni- Non-homogeni- zation zation High Egg Concen- tration 90.0 92.4 5.1 Low Egg Concen- tration 85.5 89.0 4.8 .. , - . . . - . ... . . - o - a ,4 .1 - . .. . . A . ‘ . ‘ - I . . _ . . . . a . 4 __ - .‘fl 0 . . . . 4 . . --.-s- - - .. . . n . .- .. _ _.. . . g _ .. . h - - ‘ r- r . . I . . s . . . ‘ --... --.. .. . . . .... . - . - .. . - - - - .. _ . .2“ . ‘ _.. ' ‘ .- -‘. . I - ' t . ’ r .I ‘ . - o 7 s ,, o. >‘ _ . - 4 . — 1 .- - . _ .9 . ._ .... o . -a. .s - . - a s 4 n 0.. . ‘ fl . -7- . | . . a s - . . , c . . . . .- . an - ‘- 4 a .- - a. an .4 . - _. ~ ‘ ~ . .‘ . O ‘ I . . a . O ‘ ' ’ o . . O ', . . - . . . . _ .. . .. . .. . . - . .. -.-—.. - ....4........ n n. - _ _. - - s . . -...,__- _ ' . , , ‘ . ' , l . . h . . I - , . .4 . . - 4. . ..4 .- - .. .. _..-- -. ..1 .. _ .. ~-...........n.._.-- 7--.--- _ o . A ., , . .- . ' t - u , _‘ s 4 -- — 0-4 . -- o o a. e)- .. -- 1 _ - - '5' . ‘ . _, . k- .. . ., . . . - - .. .- . . .o - - 4 . . .1 "-—-... o '0. . . D I ' 61 the variables of baked custards and the studentized mul- tiple range comparison indicated that the fresh egg cus- tard which was baked to 88° C. was significantly differ- ent in consistency at the 5% level from all DWES custards baked to 88° C. The comparison of the end internal tem- peratures showed that the 88° 0. temperature was signifi- cantly different in its effect on consistency from the temperatures of 90° 0. and 92° C. The latter 2 tempera- tures did not differ statistically from each other. This is confirmed by the fact that the DWES custards baked to 88° 0. received the lowest mean scores. Objective Tests Micrometer Agjustment Penetrometer The depth to which the cone of the Micrometer Adjustment Penetrometer penetrated the baked custards was used as a measurement of the firmness of the custards. The mean penetrometer readings on custards with the crust on and Off are included in Tables 15 and 16. The mean readings of custards with the crust on as affected by treatments, temperatures, and concentrations are shown in the 2-way tables in Table 17. The mean readings of custards from which the crust was removed and under the experimental conditions are found in Table 18. 62 TABLE 15 Mean Penetrometer Readings on Baked Custards with the Crust 0n Vari- Replications Mean able 1 2 ‘ 3 4 5 6 11 32.12 32.2 32.1 31.1 29.4 31.1 31.33 2 31.0 30.4 30.3 31.2 28.9 29.5 30.22 3 30.3 29.4 30.4 27.8 29.0 28.6 29.25 4 32.1 31.9 32.1 32.5 31.8 32.6 32.17 5 31.7 30.6 31.0 30.8 30.4 29.8 30.72 6 31.2 30.9 30.3 28.5 28.9 29.0 29.80 7 30.9 31.4 29.5 30.6 29.7 30.0 30.35 8 31.8 31.1 30.2 28.7 28.0 30.1 29.98 9 30.9 29.2 29.3 29.7 29.8 29.4 29.72 10 32.7 31.2 32.1 31.0 29.6 30.4 31.17 11 32.5 30.2 31.3 30.7 30.1 30.2 30.83 12 32.7 30.7 30.6 29.8 28.7 30.8 30.55 13 30.8 31.1 30.7 31.0 29.7 30.3 30.60 1 Refer to the key for variables on page 39. 2 Mean score of 2 readings on 1 replication of each vari- able. 63 TABLE 16 Mean Penetrometer Readings on Baked Custards with the Crust Off Vari- Replications Mean able 1 2 3 4 5 6 11 33.02 33.8 33.3 32.3 31.7 34.1 33.03 2 32.7 34.4 31.6 33.0 30.6 31.2 32.25 3 31.3 30.3 31.3 29.8 30.9 31.1 30.78 4 34.0 33.0 33.2 35.2 33.0 32.5 33.48 5 34.7 31.7 32.8 31.9 31.6 30.6 32.22 6 32.9 31.4 32.1 30.1 30.7 31.7 31.48 7 32.5 33.8 32.1 32.3 32.0 32.3 32.50 8 34.1 32.9 32.1 31.3 30.5 31.4 32.05 9 33.1 31.7 31.5 31.3 30.5 32.0 31.68 10 34.2 32.2 32.6 32.6 32.5 31.9 32.67 11 32.4 33.2 33.6 32.4 32.6 32.2 32.73 12 33.4 32.0 31.9 32.0 29.9 30.7 31.68 13 32.4 33.4 32.0 31.2 31.1 31.2 31.88 1 Refer to the key for variables on page 39. 2 Mean score of 2 readings on 1 replication of each vari- able. 64 TABLE 17 Mean Scores for the Penetrometer Readings on Baked Custards (Crust 0n) under Specific Experimental Conditions Treatments Temperatures Treatment Means 88° C. 900 C. 92° C. Homogenization 381.0 365.6 354.3 30.6 Non-homogenization 369.1 364.9 361.6 30.4 Temperatures DWES Concentrations Temperature Means High Egg Conc. Low Egg Conc. 88° C. 370.1 380.0 31.3 902 0. 361.2 369.3 30.4 92° C. 353.8 362.1 29.8 Concentrations Treatments Concentration Means** Homogeni- Non-homogeni- zation zation High Egg Concen- tration 544.8 540.3 30.1 Low Egg Concen- tration 556.1 555.3 30.9 ** The high egg concentrations and the low egg concentra- tions were significantly different from each other at the 1% level of probability. -u.-. 65 TABLE 18 Mean Scores for the Penetrometer Readings on Baked Custards (Crust Off) under Specific Experimental Conditions Treatments Temperatures Treatment Means 88° C. 90° C. 92° C. Homogenization 399.1 386.8 373.6 32.2 Non-homogenization 391.0 388.7 380.2 32.2 Temperatures DWES Concentrations Temperature Means High Egg Conc. Low Egg Conc. 88° C. 393.2 396.9 32.9 905 0. 385.8 389.7 32.3 92° C. 374.8 379-0 31.4 Concentrations Treatments Concentration Means Homogeni- Non—homogeni- zation zation High Egg Concen- tration 576.4 577.4 32.1 Low Egg Concen- tration 583.1 582.5 32.4 66 An analysis of variance of the penetrometer readings from which the readings of the control were ex- cluded indicated that the differences were due to the joint effect of treatments and temperatures at the 5% level of probability on custards with the crust off. The concentration of egg protein in the DWES custards and the interaction of temperatures and treatments were significant at the 1% level in samples tested with the crust on. Significant differences existed at the 1% level between the replications of the baked custards with respect to both penetrometer tests. The rank of the mean readings of firmness of custards with the crust removed shows that all DWES cus- tards baked to 92° C. were more firm than the control and that the homogenized variables were more firm than the non-homogenized samples. In general, the weakem:gel structures were evident in the homogenized DWES custards baked to 88° C. This substantiates the slower rate of heat penetration into the custard due to the homogeniza- tion process reported by Carr and Trout (7). In the custards in which the crusts were not removed, those baked to 88° 0. ranked lowest in firmness. The mean readings indicated that dilution of the egg pro- tein by the addition of extra milk produced a more deli— cate or weaker gel structure. The custards containing 67 the high egg solids concentration baked to 92° C. were equal or greater in firmness to those custards which con- tained the low concentration of egg protein baked to the same temperature. Qu_r_c_1_ Tension Met}; The firmness of baked custards from which the crust was removed was measured by the curd tension meter. The mean curd tension meter readings of the baked custards are given in Table 19. Table 20 shows in 2-way table form the mean readings of the custards as affected by the treatments, temperatures, and concentrations of egg solids obtained from this test. An analysis of variance of the readings on the custards from which the readings of the control were ex- cluded showed that the concentration of egg protein affect- ed the firmness of the gel structure. Variation due to replication was significant at the 1% level of probabil- ity. An interaction of the treatments and temperatures indicated significance at the 1% level. It is evident from the mean readings that the resistance of the custard to cutting by the knife blades of the instrument was greater in custards containing the high egg concentration than in those custards made with the low egg concentration. 68 TABLE 19 Mean Curd Tension Meter Readings on Baked Custards Vari- Replications Mean able 1 2 3 4 5 6 11 24.52 25.0 25.0 24.5 30.0 21.0 25.00 2 21.0 27.0 29.5 26.5 34.0 28.0 27.67 3 32.5 37.0 38.5 43.0 39.0 43.0 38.83 4 21.5 23.0 25.0 24.0 22.5 23.5 23.25 5 17.5 21.5 23.5 25.0 24.5 28.5 23.25 6 27.0 32.5 28.0 37.0 33.0 34.0 31.92 7 19.0 22.0 23.0 25.0 22.0 26.0 22.83 8 23.5 24.0 26.0 27.0 32.5 27.5 26.75 9 25.0 29.5 30.5 27.0 34.5 27.0 28.92 10 14.5 19.5 17.0 17.0 18.0 19.5 17.58 11 19.5 23.0 22.0 19.0 23.0 25.5 22.00 12 23.0 23.5 23.5 24.0 27.5 26.5 24.67 13 32.3 30.2 35.3 36.0 37.5 35.2 34.42 1 Refer to the key for variables on page 39. 2 Mean score of 2 readings on 1 replication of each vari- able. 69 TABLE 20 Mean Scores for the Curd Tension Meter Readings of Baked Custards (Crust Off) under Specific Experimental Conditions Treatments Temperatures Treatment Means 88° C. 90° C. 92° C. Homogenization 289.5 305.5 424.5 28.3 Non-homogenization 242.5 292.5 321.5 23.8 Temperatures DWES Concentrations Temperature Means High Egg Conc. Low Egg Conc. 88° C. 287.0 245.0 22.2 909 0. 326.5 271.5 24.9 92° C. 406.5 339.5 31.1 Concentrations Treatments Concentration Means** Homogeni- Non-homogeni- zation zation High Egg Concen- tration 549.0 471.0 28.3 Low Egg Concen- tration 470.5 385.5 23.8 ** The high egg concentrationaand low egg concentrations were significantly different from each other at the 1% level of probability. .-. e..- 70 With a rise in the end internal temperature, the gel structure of the custards became firmer as determined by the greater resistance of the custard to cutting. No significant differences in firmness were indicated by an analysis of the variance of the readings as a result of an increase in the end baking temperature. The mean scores show that the homogenized DWES custard of high egg concentration baked to 92° C. was the firmest. The control ranked second in firmness while the nonphomogenized DWES custard baked to 92° C. was next. 1229391922 The measurements for the calculations of per cent sag were used to determine firmness of baked custards. The mean per cent sag of the custards are listed in Table 21. Analysis of variance of the per cent sag calculations showed differences in concentrations significant at the 1% level of probability. The mean per cent sag for samples of the 2 concentrations are given in the 2-way tables in Table 22. Variation between replications was not evident. The results showed that additional milk tended to weaken the gel structure of DWES custards. This ac- counts for the higher percentages of sag found in custards made with a low concentration of egg solids, baked to any given end internal temperature. The strongest gel structures 71 TABLE 21 Mean Per cent Sag of Baked Custards Vari- Replications Mean able 1 2 3 4 5 6 11 25.02 28.4 38.6 31.3 27.1 28.9 29.88 2 23.7 24.5 24.2 26.6 21.8 22.7 23.92 3 17.4 14.6 21.1 17.9 21.3 18.8 18.52 4 27.4 34.0 32.7 32.9 31.3 31.6 31.65 5 28.5 25.0 26.8 31.9 24.2 25.3 26.95 6 24.5 22.9 32.6 22.9 26.1 26.3 25.88 7 27.2 26.7 25.5 26.2 26.8 23.3 25.95 8 24.5 25.0 24.0 26.8 24.2 25.0 24.92 9 26.0 18.4 18.5 26.5 21.7 23.1 22.37 10 37.0 28.9 19.6 30.2 24.8 28.4 28.15 11 27.5 23.4 28.3 26.5 28.1 27.8 26.93 12 23.5 28.5 24.5 27.1 22.9 24.5 25.17 13 26.4 28.4 27.8 26.0 23.4 24.5 26.08 1 Refer to the key for variables on page 39. 2 Mean score of 2 readings on 1 replication of each vari- able. 72 TABLE 22 Mean Per cent Sag of Baked Custards under Specific Experi- mental Conditions Treatments Temperatures Treatment Means 88° C. 90° C. 92° C. Homogenization 369.2 305.2 266.4 26.1 Non-homogenization 324.6 311.1 285.2 25.6 Temperatures DWES Concentrations Temperature Means High Egg Cone. Low Egg Conc. 88° C. 335.0 358.8 28.9 906 0. 293.0 323.3 25.7 922 0. 245.3 306.3 23.0 Concentrations Treatments Concentration Means** Homogeni~ Non-homo- zation genization High Egg Concentra- tion 433.9 439.4 24.3 Low Egg Concentra- tions 506.9 481.5 27.5 ** The high egg concentrations and the low egg concentra- tions were significantly different from each other at the 1% level of probability. . *v—u. e 4-.- o .o -. a..- . - C 4 e-.. v O-o ““-_.“ “ ‘- " . vh--M ’ ‘ ~ O