lVIESI.) RETURNING MATERIALS: Place in book drop to LJBRAfiJES remove this checkout from mun. your record. FINES wiH be charged if book is returned after the date stamped beIow. FORMULATION AND EVALUATION OF IMITATION EVAPORATED MILK By Abdulrahman Abdulla Al-Saleh A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Food Science and Human Nutrition 1984 317l3’75 ABSTRACT FORMULATION AND EVALUATION OF IMITATION EVAPORATED MILK BY Abdulrahman Abdulla Al—Saleh This study was undertaken to develop an imitation evaporated milk utilizing sweet whey, sweet cream buttermilk and other milk by-products. Additionally, this study compares the new product to normal evaporated milk. Two methods were used to produce imitation evaporated milk; a) by' direct-formulation Unixing the ingredients without evaporation) and b) by evaporation (fluid—base). Sweet cream buttermilk, sweet whey, isoelectric casein, and soybean oil were used to prepare the imitation evaporated milk. In addition, corn syrup solids were added to direct-formulation milk to increase total solids. The addition of disodium phosphate and sodium citrate increased the stability of imitation evaporated milk as determined with heat and alcohol test, whereas the addition of calcium ions decreased it. The addition of ascorbic acid (0.107. w/v) or sodium hexametaphosphate (0.10% w/v) in- hibited the development of browning in direct-formulation product (D—F), whereas (0.15% w/v) of ascorbic acid, and (0.15% w/v) of sodium hexametaphosphate was required to Abdulrahman Abdulla Al—Saleh prevent the browning defect in the fluid-base (F-B). The D-F product possessed normal heat stability and a low level of discoloration. The F-B product exhibited enhanced flavor, body, and mouth feel, but was accompanied by an increase in discoloration which could be lessened by the addition of ascorbic acid or sodium hexametaphosphate. To the memory of my beloved Father and Mother. ii ACKNOWLEDGMENTS I would like to express appreciation to my professor, Dr. J.R. Brunner, Professor of Food Science, for his con— tinuous and patient advice throughout my graduate program. Special appreciation is expressed to Dr. L.E. Dawson, Professor of Food Science, Dr. A.M. Pearson, Professor of Food Science, and to Dr. E.S. Beneke, Professor of Botany and Plant Pathology, for serving on my guidance committee. A special thanks to Ursula Koch for her continual assistance in the laboratory. iii TABLE OF CONTENTS TITLE PAGE DEDICATION ACKNOWLEDGMENTS LIST OF TABLES LIST OF FIGURES INTRODUCTION REVIEW OF LITERATURE Recombined Evaporated Milk Factors Effecting Heat Coagulation of Evaporated Milk Correlation between the Alcohol Test and Heat Coagulation Forewarming of Evaporated Milk Effect of Milk Salts on Heat Stability of Evaporated Milk Browning of Evaporated Milk EXPERIMENTAL Materials and Methods iv Page ii iii vii ix 11 14 16 16 TABLE OF CONTENTS (CON'T) Formulation and Manufacturing Procedures Preparation of Sweet Cream Butter— milk and Sweet Whey Direct-formulation Imitation Evaporated Milk Fluid-base Imitation Evaporated Milk Analytical Procedures Determination of Total Calcium Ionic Calcium Determination Alcohol Tests Salt Tests Evaluation of Forewarming Treatment Browning of Imitation Evaluation Milk Evaluation of Homogenization Sensory Evaluation Procedure RESULTS AND DISCUSSION The Effect and Control of Calcium as It Relates to Heat Stability of Imitation Evaporated Milk Prediction of Heat Stability with the Alcohol Tests The Binding of Ionic Calcium by Na-citrate Prediction and Control of Heat Stability with the Stabilizing Salt Test Forewarming Effect on the Heat Stability of Imitation Evaporated Milk Page 18 18 20 22 23 23 24 24 26 27 27 28 29 3O 3O 30 34 37 49 TABLE OF CONTENTS (CON'T) Page The Effect of Selected Substances,on pH, and CaCl solution on the Develop- ment of Brow; Discoloration 51 The Effect of Homogenization on the Emulsion of Imitation Evaporated Milk 59 Sensory Evaluation of Imitation Evaporated Milk 62 Experimental Imitation Evaporated Milk- 64 Commercial Trials CONCLUSION 70 BIBLIOGRAPHY 71 vi Table Table Table Table Table Table Table Table Table Table Table Table Table 12. No. 10. 11. LIST OF TABLES Page World production of evaporated milk 2 Properties of sweet cream buttermilk and sweet whey 18 Calculations for the manufacture of direct-formulation imitation evaporated milk 21 Effect of CaCl solution on the alcohol test (Direct-formulation product) 32 Effect of CaCl solution on the alcohol test (Fluid-base product) 33 The effect of Salt-balance on the alcohol test (Direct formulation product) 35 The effect of Salt-balance on the alcohol test (Fluid—base product) 36 The concentration of ionic calcium bound to citrate 38 The effect of disodium phosphate on direct formulation product 40 The effect of disodium phosphate on fluid-base product 42 The effect of additional varying amounts of disodium phosphate upon the coagulation time of fluid-base product 43 The effect of additional varying amounts of disodium phosphate upon the coagulation time of direct formulation product 45 vii Table Table Table Table Table Table Table Table Table Table Table Table No. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. LIST OF TABLES (CON'T) The effect of CaCl upon the coagulation time of fluid-base product The effect of CaCl upon the coagulation time of direct formulation product The influence of forewarming treat- ment on heat stability of imitation evaporated milks The effect of ascorbic acid on the browning of imitation evaporated milks The effect of sodium hexameta- phosphate on the browning of imitation evaporated milks Effect of pH on the browning of imitation evaporated milks Effects of CaCl on the browning of imitation evgporated milks Sensory evaluation of imitation evaporated milks Properties of imitation evaporated and commercially-processed evaporated milks Selected properties of experimental imitation evaporated milk - commercial trials Selected properties of experimental imitation evaporated milk - commercial trials viii Page 46 47 50 53 54 57 58 63 65 66 68 Figure No. Figure Figure Figure Figure Figure LIST OF FIGURES Schematic representation for the production of sweet cream butter- milk and sweet whey Device used to collect ultrafiltrate for ionic calcium determination Form used for sensory evaluation of imitation evaporated milks Photomicrographs of fluid-base, direct-formulation and commercially processed evaporated milks (100x magnification) Photomicrographs of heat-coagulated fluid-base and direct-formulation imitation evaporated milks (100x magnification) ix Page 19 25 29 6O 61 INTRODUCTI ON Evaporated milk is a commercially sterile, concentrated milk containing not less than 7.9% (w/w) fat and not less than 25.9% (w/w) total solids. Its primary advantage lies in its convenience, relatively long shelf life, and low cost. Thus, the world population of evaporated milk has increased from 1969 to 1981 (See Table 1). The primary purposes of the study were to develop an imitation evapo— rated milk product and to compare the new product with normal evaporated milk. By utilizing materials such as sweet cream buttermilk, sweet whey, isoelectric casein, and partially hydrogenated soybean oil it should be possible to formulate imitation evaporated Hulk” Thus, the following advantages would be achieved: 1) a utilization of whey (by-product of cheese manufacture), 2) a development of local industries e.g. vegetable oil production, cheese production, 3) and. the elimination of the need to refrigerate milk products during transportation, especially in developing countries. 2 Table 1. World Production of Evaporated Milka Area c Years 1969—1971 1979 1980 1981 World 4,540,704b 4,648,310 4,685,397 4,749,160 N. America 1,620,165 1,347,425 1,340,030 1,353,665 s. America 135,700 167,374 160,825 180,400 Asia 427,013 582,474 616,900 642,073 Europe 1,809,295 1,880,482 1,892,100 1,923,210 Australia 79,670 88,626 88,281 77,212 aFrom FAO Production Yearbook, V. 35, 1981. bMT = million tons. cAverage annual production of evaporated milk. LITERATURE REVI EW Recombined Evaporated Milk Recombined, filled, and imitation milks have gained an increasingly important role in the marketplace, es— pecially in supplying large population areas with milk and milk products. Recombined milk products are derived by combining non-fat milk solids with one of the sources of milk fat. These mixtures may be packaged with or without water. Filled evaporated milk is produced by combining skimmed milk with any fat or oil other than milk fat. Imitation milk products are simulated products which have no conventional products in their formulation. Lactose, demineralized whey solids, and sodium caseinate are not considered as milk products (Lampert, 1975). While the method of manufacturing varies slightly, the composition should meet legal standards. Kieseker (1982) reviewed the literature on the formulation and manufacture of recombined evaporated milk. Water is heated to 45-550C in preparation for the dispersion of skim milk powder by using a high speed blade. Liquid fat is then added. The preheating and homogenization temperature is usually 55-600C. The homogenization pressure varies in the range of 2000-2500 4 psi on the first stage, followed by 500 psi at the second stage. 'Fat stability in the product is increased by in- creasing the pressure of homogenization. The goal is to ensure fat dispersion. Failure to achieve a stable fat dis— persion results in fat separation. The addition of citrate, phosphate or calcium ions is required to stabilize the protein against the effects of heat denaturation during sterilization. However, the addition of these salts should be kept at minimum levels since they adversely affect flavor when used in high concentrations. Kieseker (1982) found that the main problem encountered during the production of recombined and filled milks is the possibility of protein coagulation during sterilization. Alyer (1969) described a method for the preparation of artificial milk and found out that solubilizing acid casein at pH values in excess of 9.0 had a detrimental effect on the caseinate, probably because of its effect on the sulphur amino acids. Additionally, he reported that acid casein imparted better keeping qualities to artificial milk than neutral sodium caseinate and does not form sedi- ment in the presence of normal levels of calcium ions. Factors Effecting Heat Coagulation of Evaporated Milk The principal problem in the manufacturing of evapo— rated milk is heat coagulation.*which. occurs during the sterilization process. The heat process effects the salt and protein components of milk and causes a heavy body and 5 precipites the milk protein. The effect of heat upon various constituents of milk has been studied extensively (Hunziker, 1949; Sommer and Hart, 1926). The time and temperature of heating are primarily responsible for producing the changes that occur during heating. Hunziker (1949a) reviewed the factors affecting the heat stability of evaporated milk and identified two main types of problems: 1) those which effect the properties of the milk, and 2) those influencing the efficiency of manufacturing. The first group includes: a) acidity of milk (the hydrogen ion concentration and titratable acidity). Any increase in the acidity decreases the heat stability. b) The milk proteins. Hunziker (1949a) agreed with Webb (1935) that the problem of heat stability can be attributed to the nature of the calcium caseinate system and c) the salt-balance which includes the cations (calcium and magne- sium) and the anions (phosphate and citrate). The second group includes: a) a forewarming temperature below the boiling point (190-2100F) for 10-25 minutes is adequate for enhancing the heat stability of evaporated milk; b) the heat coagulation temperature decreases as degree of concentration increases; c) a high homogenization pressure lowers the heat stability of evaporated milk; and d) heating after concentration of 150°C (302°F) with no holding produced maximum stability. Sommer and Hart (1919) reported that the milk salts constitute the main factor in heat coagulation of fresh 6 milk. Contrary to this, Rogers, Deysher, and Evans (1921) concluded that the salts of milk are a minor factor in determining coagulation time, due to the rearrangement of acid-base relations in the condensing process. They also concluded that there is no definite relationship between the true acidity (hydrogen ion concentration) of the milk before sterilization and the coagulation temperature of evaporated milk. Sommer and Hart (1922) criticized this conclusion, stating that they failed to find any relation- ship between the coagulation of evaporated milk and the salt-balance. They speculated on the inadequancy of the analytical method utilized by the Rogers group. Holm, Webb and Desher (1932) observed that the salt-balance as deter- mined by analysis of milk has no direct relation to the heat stability of fresh milk or its evaporated products. Millory (1915) found that when milk was heated there was a slight increase in titratable acidity. Maxcy and Sommer (1954) reported that factors influencing the heat stability were a) forewarming, b) homogenization, c) concen— tration, d) presence of rennet-producing organisms, e) acid and pH, f) albumin and globulin content, g) relative concen— tration of ions, h) total ion or salts concentration, and 1) possible differences in the casein components. Dejongh (1978) stated that increasing the solids-not— fat concentration from 16 to 18 percent reduced the heat stability from 57 to 42 minutes at 120°C. They also demonstrated that increasing the fat concentration from 8% 7 to 10% reduced the coagulation time from 49 to 39 minutes at 130°C. Newslead, Conaghan and Sanderson (1976) showed that evaporated milk prepared from concentrated whey com bined with milk fat had a distinct heat stability/pH relationship. Correlation between the Alcohol Test and Heat Coagulation The alcohol test is one of the tests used in the evaporated milk industry to detect suitability of milk for the sterilization process. Some investigators, such as Dahlberg and Garner (1921) and Sommer and Binney (1923), reported that this test is reliable for detecting the quality of milk. Others, such as Anne, Beton and Albery (1926) reported that the alcohol test is not reliable. Ayers and Johnson (1915) mentioned that the addition of acid to milk would change dibasic phosphate, which is present in milk, to a state in which it is possible to precipitate the casein by alcohol. They considered milk from a single cow to be abnormal if it showed a positive alcohol reaction. A positive alcohol test with mixed milk was attributed to bacterial action, but they did not show a definite relationship between the number of bacteria in milk and the alcohol test. Dahlberg and Gerner (1921) stated that the alcohol test showed possibilities of being a reliable and practical test for determining the quality of milk for condensing. Sommer and Binney (1923) reported that the salts of milk have an 8 important effect on alcohol coagulation. A slight increase in calcium or magnesium caused a positive alcohol test, whereas an increase: of' phosphate, citrate, chloride and sodium did not result in a positive alcohol test. Anne, Bentin and..Albery (1926) stated. that whether the alcohol test is negative or positive does not prove anything relative tn) the heat stability of milk. Changing alcohol positive milk to alcohol negative by adding ci— trate or other buffers does not increase the stability unless a critical combination of salt-balance and pH is approached. This condition was found in the majority of samples, which they studied at or near the point where the milk is negative to 70 percent alcohol and positive to 75 percent alcohol. White and Davis (1958) reported that the most important factor governing the stability of the case- inate complex in milk to alcohol is the concentration of bivalent cations. Deman and Batra (1964) found that alcohol test values increased with the addition of phosphate or citrate. These anions act in similar ways in complexing calcium ions and thus increasing milk stability. Forewarming of Evaporated Milk The time of milk coagulation at a given temperature varies with the nature of the forewarming treatment. It is known that the forewarming temperature has a great effect on the stability of evaporated milk. Sommer (1923) stated that the effect of forewarming was largely due to the 9 precipitation of milk albumin (whey proteins), since the albumin content of milk has an affect upon its coagulation. He suggested that the forewarming treatment decreased the coagulating tendency by promoting the precipitation of soluble calcium. Webb and Bell (1942) found that the heat stability of evaporated milk of 26% total solids content was increased as much as six times that of control samples when forewarmed to 95°C (203°F) for 10 minutes. Bell and Webb (1943) concluded that the heat stability of evaporated milk may be greatly increased by high tempera— ture forewarming to 95°C (203°F) for 10 minutes without any effect upon the color. Deysher, Webb and Holm (1929) stated that the heat treatment of milk affects the heat stability of evaporated milk. Temperatures up to 70°C for 10 minutes decreased the heat stability while higher temperatures increased it. Bell, Curran and Evans (1944) reported that the forewarming treatment of only 65°C (149°F) for 10 minutes did little to increase heat stability. Hunziker (1949b) stated that forewarming fluid milk was the most common method for inducing increased heat stability in evaporated milk. Rose (1962) found that fore- warming milk at 120°C for 10 minutes decreased milk pH by about 0.09 and lowered the pH at which maximum heat sta- bility occurs by about 0.16. He also found that the behavior of an individual milk after forewarming depends upon its original ph relative to the pH at maximum heat stability. 10 Griffin, Hickey, and Chandler (1976) reported that preheating tends to increase the heat stability of milk when the pH of milk is lower than the pH of maximum heat stabili— ty. When the pH of the milk is greater than that of the maximum heat stability, forewarming tends to reduce the heat stability. Pearce (1979) concluded that the only effect of forewarming was to change the pH of maximum heat sta- bility from about 6.6 to 6.5. Newstead, Conaghan, and Baldwin (1979) noted that when forewarming was carried out following both homogenization and evaporation, no increase in heat stability was induced by the forewarming treatment. When milk was forewarmed after either homogenization or evaporation, the evaporated milk was considerably less heat stable than normally pro— cessed milk in which forewarming treatment preceded homogenization. Sweetsur and Muir (1980) showed that the combination of £1 suitable stabilizer, such as NazHPOA, and forewarming could induce a large increase in the heat sta- bility of both skim and concentrated skim milk. Sweetsur and Muir (1982) found that the heat stability of concentrated milk could be enhanced to the greatest extent by high temperature forewarming (145°C for 5 sec.), two-stage of homogenization, and addition of sodium phosphate. Newstead and Baucke (1983) stated that the greatest heat stability of the raw skim milk was obtained by using forewarming treatments of 110 - 120°C for 120-240 sec. Effect of Milk Salts on Heat Stability of Evaporated Milk Milk salts play an important role in the heat stability of evaporated milk. The successful manufacture of evapo- rated milk is largely dependent on the ionic equilibrium (cations and anions) of salts and the way they affect the stability of the calcium caseinate complex. Sommer and Hart (1919) concluded that casein required a definite optimum calcium content for maximum stability, and that the calcium content of casein is controlled by the concentration of phosphates, citrates, and magnesium. Benton and Albery (1926) found that there was an optimum balance of buffer salts and pH within a pH range of 6.58 — 6.65m The salt—balance was the most important factor, but outside the optimum pH range, pH had a greater influence on stability. Sommer and Hart (1926) showed that calcium and mag— nesium on the one hand, and phosphate and citrates on the other hand, have opposite effects on heat coagulation; an excess of either one of these two ionic groups will cause the coagulation" ‘To prevent heat coagulation of the milk, it should have a proper balance of salts (cations and anions). They found that in some of the milk, addition of a suitable amount of disodium phosphate or sodium citrate, and in other samples by the addition of calcium acetate or magnesium chloride.. They explained that the reason for the difference between the heat coagulation of the unconcen— trated milk and that of evaporated milk was due to the 11 12 precipitation of salts, and concomitant increases in the hydrogen ion concentration. Holm, Webb, and Deysher (1932) showed that there was an increase in heat stability of milk as the concentration of magnesium and calcium became greaten Seeks and Smeets (1948) stated that precipitation of fresh milk was due to increased calcium ion activity which could be corrected by the addition of sodium citrate. Zittle, Dellamoneca, and Custer 91957) concluded that both phosphate and citrate act by binding calcium, which in the case of phosphate leads to the formation of insoluble calcium phosphate. In the case of a calcium-phosphate/ calcium caseinate complex, an excess of calcium precipitated both calcium caseinate and tricalcium phosphate. Evenhuis and DeVaries (1957a) reported that the binding capacity of casein for calcium in a given milk is related to the composition of the milk protein, the citrate con- tent, and its heat treatment. Evenhuis and DeVaries (1957b) found that the composition of collodial calcium phosphate was always the same when precipitated at pH values of 6.7, 8.0 or 9.0, possessing a (Mg + Ca)/P ratio of about 1.60. They concluded that milk with high citrate and low phosphate contents, together with a low collodial calcium phosphate content, could be unstable to heat (Evanhuis 1957). little and Pepper (1958) reported that CaClz-induced aggregation of casein occurred in two stages: an immediate aggregation upon the addition of CaCl2 followed by a period of gradual aggregation. The principle function of calcium 13 in casein aggregation is a ramification of its effect on the hydration and charge of the casein complex. Zittle, Della— monica, Ruddard and Custer (1957) found that both heated and unheated B-lactoglobulin in the presence of calcium bound the same amount of calcium in the pH range of 6 to 8. Sub- sequently, Dellamonica, Custer, and Zittle (1958) observed that a dilute solution of’ B-lactoglobulin. (1%0 was not precipitated by calcium chloride when heated in the pre— sence of casein. The reason for this, they postulated, was that the casein reduced the concentration of calcium chloride available to the B-lactoglobulin. Rose (1961a) concluded that the nmximum heat stability of milk in the pH range of 6 to 8 was significantly cor- related with the following salt ratios: a) soluble calcium/ soluble inorganic phosphorus, b) calcium ions/soluble inorganic phosphorus, and c) soluble magnesium plus soluble calcium/soluble citrate plus soluble inorganic phosphorus. Rose (1961b) observed that by increasing the calcium con- tent, the maximum heat stability' was decreased, and 'by increasing the phosphate content there was an increase in the maximum heat stability; This effect, however, was reversed at high levels of phosphate. Rose (1962) also noted that the removal of collodial phosphate from milk by dialysis or acidification increased heat stability. Deman and Batra (1964) showed that when 60 mg/100ml of calcium was added to skim milk the ratio of ionic to soluble calcium shifted from 0.56 to 0.64, and the ratio of soluble 14 to toal calcium shifted from 0.33 to 0.42. This indicated that only one quarter of calcium ions remained in the ionic form. They also found that the destabilizing effect of adding 10 mg/100 ml of calcium ions was counteracted by approximately 60 mg of added citrate. Zittle (1969) reported that k-casein was not precipitated by heating in the absence of calcium ions, but k-casein was precipitated when calcium ions were subsequently added. Wedit (1981) pointed out that the commonly used heat treatment i.e., preheating, pasteurization, and steriliza- tion, increased the sensitivity of the whey proteins to calcium ions and caused denaturation of the whey protein so that the susceptibility of whey proteins to denaturation depends on the presence of calcium ions. Horne and Parker (1981) reported that the addition of Ca would lead to higher concentration of colloidal calcium phosphate and such addition leads to reduced Etoh stability. They also reported that the addition of phosphate would increase colloidal phosphate, or Ca phosphate itself, but did not have an equivalent effect. Phosphate, at the level added, had no observable effect on Etoh stability, while Ca phosphate had a destabilizing effect. Browning of Evaporated Milk Evaporated milk usually has a darker color than fresh whole milk; a ramification of the prolonged heat treatment of evaporated milk. For many consumers, evaporated milk 15 should possess very little brown color. Experimental studies on the factors causing color formulation in evaporated milk are very limited. There are two types of browning involved in the browning of evaporated milk: a) the Maillard—type or amino-sugar browning; and b) the caramelization of lactose. Most investigators support the first type (Jenness and Patton, 1959a). There— fore, lactose and casein are the two major constituents involved in the browning of evaporated milk. Webb and Holm (1930) reported that these changes in color were due to the effect of heat; whether during storage sterilization or forewarming. Hunziker (1949c) stated that the lactose-protein reaction was responsible for the dark color of milk. The NH2 group combines with the CHO group of lactose, leaving the acid group free, which causes a reduction in the pH and the eventual formation of a colored product. Jenness and Patton (1959b) reviewed the following factors which effect browning in the fluid milk system: a) properties of milk; b) total solids concentration; c) heat treatment; d) pH; e) oxygen; f) storage time and tem- perature; g) various added compounds; and h) processing steps of forewarming and sterilization. They reported that as the concentration of milk solids, the concentration of lactose, and the pH increased, browning increased. From a stability point of view, as the stabilizer level was increased the color intensity increased. This was attri- buted to a shift in pH due to the alkaline stability salts. EXPERIMENTAL Materials and Methods The principal chemicals used in this study are listed below. The water used was distilled. The chemicals used in the calcium determination, sodium acetate and sodium chloride, were purchased from Mallinckrodt, Inc.; ammonium purpurate was purchased from Sigma Chemical Company; sodium citrate and disodium ethylenediamine tetraacetate were obtained from IFisher Scientific Company; phosphoric acid was purchased from J.T. Baker Chemical Co.; calcium chloride and potasium chloride were obtained from Mallinckrodt. The standard titration solution was prepared by dis— solving 10 grams of disodium ethylenediamine tetraacetate and 2 grams of sodium hydroxide pellets in water which was made to one liter. The solution was standardized against a standard solution of CaCl2 to be equivalent to approxi- mately 1.0 mg of calcium per milliliter (Jenness, 1953). Calcium indicator was prepared by grinding 100 grams of sodium chloride and 0.2 grams of ammonium purpurate into an intimate mixture. Chemicals used in browning studies include ascorbic acid purchased from Mallinckrodt, and sodium hexametaphos- phate obtained from the Fisher Scientific Company. 16 17 An anion exchange resin was used to prepare an ion exchange columna 'The column was backwashed with water and several portions of IN sodium acetate followed by rinsing with distilled water. .A superspeed centrifuge, Servall Type SS-1, was used to obtain ultrafiltrate product for ionic calcium determina- tion. Centrifuge tubes (50 ml) were fitted with a per- forated plexiglass platform and support ring served as a support for specimens placed in Visking tubing bags. A laboratory-size Delaval Separator was used to separate cream from pasteurized milk. A Logeman Laboratory Homogenizer Model C-8 was used to homogenize the imitation evaporated milk preparations. Photomicrographs of the fat phase in imitation evaporated milks were produced with a Microstar, series 10, American Optical Co. Microscope equipped with a poloroid camera. An oil bath equipped with a thermoregulator (i 1°C) and mixer was used for temperature stability evaluations. Temperatures ranging from 118°C (245°F) to 132°C (270°F) were used. Capped Pyrex tubes (15 ml) were employed as sample holders, fitted with Septum—Cap Teflon discs, 13 mm inside diameter. Formulation and Manufacturing Procedures Preparation of Sweet Cream Buttermilk and Sweet Whey The main constituents used in the manufacture of imita- tion evaporated milk were: sweet whey, sweet cream butter— milk, soybean oil, and isoelectric casein. The major steps involved in producing sweet whey and sweet cream butter milk are shown in the schematic diagram (See Figure 1). The raw milk was obtained from the MSU dairy barn. There is no accurate test for determining the ‘heat stability of raw milk which will predict with certainty the coagulation tendency of the manufactured product. However, an alcohol test can be used to distinguish abnormal ndlkg Raw milk used to produce sweet whey and sweet cream buttermilk had a pH 6.58 and a negative alcohol test. Total solids determination was accomplished by using a Mojonnier Milk Tester. The Babcock method was used to determine the fat content (See Table 2). Table 2. Properties of sweet creanl buttermilk. and sweet whey Property Product pH TS% Fat% Total Calcium Calcium ions Sweet cream mg% buttermilk 6.58 9.66 0.36 70 18 Sweet whey 6.47 6.50 -— 14 3 18 Raw Milk (from MSU Dairy Barn) Batch Pasteurization (145°F/30 min.) Cooling to 100-1100F Separator Cream Skim Milk Shaking "Churning" ‘ Rennet Extract /\ /\ Butter Sweet Cream Buttermilk Sweet Whey Curd Figure 1. Schematic representation of the procedure em- ployed for producing sweet cream buttermilk and sweet whey. 19 20 Two methods were used to manufacture imitation evapo- rated udlkx an evaporative-concentration (fluid—base) method and a direct formulation procedure. For both methods the same ingredients were used except that in the direct— formulation method, corn syrup solids were used to balance the carbohydrate composition. Direct-formulation Imitation Evaporated Milk The formulation of the components used in the direct method consisted of 50% (V/V) sweet whey and 30% (V/V) sweet cream buttermilk. By calculating the shortage of milk ingredients, the amount of soybean oil, isoelectric casein, and corn serum solids required to achieve a legal composi~ tion (25.9% TS and 7.9% fat) was determined. Data in Table 3 show the calculation procedure for formulating the direct method imitation evaporated milk. Mixing of the ingredients was carried out by increasing the pH of the whey to 8.0 with a mixture of KOH/NaOH (4:1) prior to the addition of isoelectric casein. This operation was accomplished at a low temperature to reduce the degrada— tion of casein. The pH was neutralized to 6.7 with H3P04. Then, the sweet cream buttermilk was added and the mixture was divided into three portions. The first part of the mixture was not heated, the second part of the mixture was forewarmed to 87.5°C (190°F) for five minutes and the third part of mixture was forewarmed to 93.50C (200°F) for ten minutes. This was done to compare the effect of the 21 Table 3. Calculations for the manufacture of direct formu- lation imitation milk. Fat Protein Lactoss Salts or CSS __________________ ‘%--------—--------- 50% Sweet crgam buttermilk 0.18 1.8 2.35 0.35 30% Sweet whey? —— 0.21 1.41 0.21 Total 0.18 2.01 3.76 0.56 Desired 7.9 6.8 9.03 Need 7.72 4.79 5.27 Oil IECd csse aCorn syrup solids. waeet cream contains 0.36% fat, 3.6% protein, 4.7% lactose and 0.7% salts. cSweet whey contains 0.7% protein, 4.7% lactose, and 0.7% salts. dIEC: isoelectric casein. eCSS: corn syrup solids. forewarming treatment. This mixture was cooled to 38.50C (100°F). Corn syrup solids were added and the mixture cooled to 4°C (40°F). The non-fat solids content of the direct—formulation product was determined to ascertain that the level of solids was not less than 18%. The formulated milk was warmed to 65°C (150°F) and partially hydrogenated soybean oil (up 92°F) was added while stirring. 'IWo stage-homogenization 22 (2,000/500 psi) was accomplished at 65°C (150°F). This direct-formulation product was cooled immediately after homogenization to 22°C (70°F) and stored at 4°C (40°F) for subsequent experiments. Alternately, the same procedure was followed to produce a direct-formulation product, but with 20% (V/V) of sweet cream buttermilk, and 80% (V/V) of sweet whey. The product which was produced by this formula tested and looked like whey, thus, it was rejected. Fluid-base Imitation Evaporated Milk To manufacture imitation evaporated milk by this ap- proach, the following procedure was followed. The formula consisted of 80% (V/V) of sweet whey, 20% (V/V) sweet cream buttermilk, and3% (W/V) of isoelectric casein. The {Hi of the whey was increased to 8.0 with KOH/NaOH (4:1) and the prescribed amount of isoelectric casein was dissolved at low temperature. Upon complete dissolution of the isoelectric casein, the pH was neutralized to 6.7 with H3P04. Then, sweet cream buttermilk was added to the mixture and the mixture was divided into three portions. The first portion of the mixture was not heated, the second portion of the mixture was forewarmed to 87.5°C (190°F) for five minutes and the third portion of the mixture was fore— warmed to 93.500 (200°F) for ten minutes. This was done to compare the effect of forewarming treatment. Each mixture was concentrated by evaporat ive 23 condensation at 50°C and 28 inches of vacuum until a TS content of 18% was attained. Partially hydrogenated soybean oil (m.p. 92°F) was added and agitated. Two-stage homogeni- zation (2000/500 psi) was performed. The resulting fluid- base product was cooled to 22°C (70°F) and stored at 4°C (40°F) for subsequent analysis. Analytical Procedures Determination of Total Calcium Ten milliliters of milk were placed in a 100 ml volume- tric flask and diluted with 20 ml distilled water. Two milliliters of 1N hydrochloric acid were added and the sample allowed to stand for 10 minutes, after which 2.5 ml of 0.5 N sodium hydroxide were added. the acid dissolves the collodial calcium salts and disperses the casein on the acid side of its isoelectric point. Addition of alkali brings the pH to 4.0 whereupon the casein is precipitated and the calcium remains in solution. The contents of the flask were made to volume, and thorough- ly mixed. The precipitate was filtered off; leaving a water clear filtrate. Ten ml of the filtrate was passed through an anion exchange column, followed by two 10 ml portions of distilled water to rinse the column. The entire effluent was collected. To determine total calcium to 30 ml of ion exchanged solution, 1 to 2 ml of 1.5 N sodium hydroxide was added to bring the pH above 10 as determined with universal indicator 24 paper. Then 1 scoop (0.2 gram) of prepared calcium indi- cator was added. The solution was titrated with stand- ardized enthylenediamine tetraacetate solution to a purple color that does not change on addition of another drop of titrant. Ionic Calcium Determination One end of the dialysis membrane (approximately 10 cm length) was twisted and a small knot was tied and then filled with 15 m1 of imitation evaporated milk. The mem— brane was closed with a small knot and tied. Cheese cloth was wrapped and placed into a 50 ml centrifuge tube and centrifuge for 15 minutes at. approximately 5000 rpm (See Figure 2). To approximately one milliliter of centrifugal ultrafiltrate, 3-4 ml of distilled water was added. One milliliter of 1.5 N sodium hydroxide and 0.1 gram of the prepared calcium indicator were added, and the solution was titrated. with ethylenediamine tetraacetate solution to .a purple color that did not change on addition of another drop of titrant. The titer was converted to calcium con- centration. Alcohol Tests Two ml of imitation evaporated milk samples were mixed with 65%, 70%, and 75% alcohol and checked for coagulation. For most accurate results, the addition should be made rapidly. 1 inch Centrifuge Tube Cheese Cloth Dialysis Membrane 15 ml of Milk Perforated Support Supporting Ring Figure 2. Device used to collect ultrafiltrate for ionic calcium determination. 25 26 To determine the effect of 0.25 M Na-citrate solution (n1 the stability of milk to alcohol, different concentra- tions of 0.25 M Na-citrate were added to 2 m1 of imitation evaporated milk. To determine what influence the salt-balance in milk has on its stability to alcohol, varying quantities of 0.25 M CaCl2 solution were added to 2 ml of imitation evaporated milk. To determine the amount of 0.25 M Na-citrate bound to calcium ions, 0.375 ml of 0.25 CaCl2 solution, which made the alcohol test distinctly positive, was added to 15 ml of imitation evaporated milk. One and one-half milliliters of Na—citrate were added to the direct-formulation specimen and 1.875 ml of Na-citrate to the fluid-base specimen. These concentrations of Na-citrate prevented the coagulation encountered in the previous test. Then, ionic calcium was determined. Salt Test To determine the proper amount of the stabilizing salt (NaZHPOA) to add, a solution containing 10 grams of dry salt dissolved of the 10% disodium phosphate solution were added to 5 m1 portions of imitation evaporated milk in sealed tubes. The milk tubes were submerged in the oil bath for sterilization at 118°C (245°F) for 15 minutes. After the sterilization process, color, viscosity, and coagulation were evaluated. Viscosity was assessed by measuring the 27 flow out time from a 3 ml pipette. A stop watch was used to monitor the time. The coagulation time was evaluated as follows. Dif— ferent amounts of 10% NazHPO4 solution and distilled water were added to 5 ml of imitation evaporated milk. Milk tubes were submerged in the oil bath which had been heated to 132°C (270°F). Coagulation time (minutes) corresponded to the appearance of coagulated particles. Similarly, the influence of varying amounts of 0.25 M CaCl2 on the coagulation time of the evaporated milk specimens was monitored. Evaluation of Forewarming Treatment To determine the effect of forewarming on the heat stability, samples were taken from imitation evaporated milk manufactured by the direct-formulation and fluid-base methods. The first group of samples was not heated. The second group of samples was heated to 87.5°C (190°F) for five minutes. Remaining samples were heated to 93.5°C (200°F) for ten minutes. Following the forewarming treat- ment, the coagulation time at 132°C (270°F) was determined. Browning of Imitation Evaporated Milk To investigate the effect of selected substances in preventing the discoloration of imitation evaporated milk, different concentrations of 10% ascorbic acid solution were added to 10 ml of imitation evaporated milk. Distilled 28 water was added to eliminate the dilution factor. Also, various amounts of a sodium hexametaphosphate solution were added 111 the same manner. The color was subjectively com- pared to that of commercially-processed, filled evaporated milk. To determine the effect of pH on browning of imitation evaporated milk, the pH was adjusted to different levels by addition of various amounts of M/10 HCL solution and M/4 NaOH solution to 5 ml of imitation evaporated milk. The color of the sterilized sample was compared subjectively with the control sample. To determine the effect of pH on browning of imitation evaporated milk as a result of the addition of 10% sodium hexametaphosphate solution and 10% disodium phosphate solu- tion, various concentrations were added to 5 ml of imitation evaporated milk. The color was monitored as before. To determine the effect of ionic calcium on discolora- tion of imitation evaporated milk, different concentrations of M/4 CaCl2 solution were added to 5 ml of imitation evaporated milk. The color was monitored as before. Evaluation of Homogenization After sterilizing .and. cooling, slides were prepared from both types of imitation evaporated milk. From each product and without diluting, a sample sufficient to cover the area under the slipcover was taken. The slipcover was pressed slightly to achieve a thin layer. A 10 x lens 29 was used to examine the field. the oil immerSion lens was employed to enlarge the field 100 times for making photo— micrographs. Similarly, slides from both samples were prepared at the time of coagulation at 270°F. Sensory Evaluation Procedure Ten participants were asked to judge the samples on a 1 to 5 scale as compared with a commercial product. Six of the ten participants were considered dairy product experts. The evaluation was done in the environment of the research laboratory. Figure 3 represents a copy of the evaluation form used. Check the samples and select one of the following numbers: 1. Very Poor 2. Poor 3. Fair 4. Good 5. Excellent Visual Mouth feel Sample Color texture (body) Flavor (smooth, coarse) Odor Figure 3. Sensory Evaluation Form. RESULTS AND DISCUSSION About 3 liters of imitation evaporated milk were manu- factured by both the direct-formulation and the fluid—base procedures. Constituents acceptable for the formulation of direct- formulation product included 50% sweet whey and 30% sweet cream buttermilk. For the fluid—base method, 20% sweet cream buttermilk and 80% sweet whey were employed. The proportions were selected based on: a) the lowest contents of sweet cream buttermilk and b) the highest contents of sweet whey which were acceptable on the basis of flavor, mouth feel and texture. Following the production of imitation evaporated milk, numerous experiments were performed to compare this new product with normal evaporated milk and for quality improvement. The Effect and Control of Calcium as‘It’Relates to'Heat Stability Offlmitation‘Evaporated Milk Prediction of Heat Stability with the Alcohol Test Alcohol test furnished direct evidence of instability of evaporated milk toward heat treatment. Alcohol exerts 30 31 denaturation and dehydration action on the protein system of milk, precipitating calcium caseinate at critical concen- trations. The imitation milks manufactured by both methods were stable to 70% alcohol. Therefore the milk samples should be stable to heat treatment. This test is not sufficiently sensitive to show the heat stability of fluid milk samples, but is capable of detecting abnormal milk. Milk salts are of importance and. to idetermine the effect of these salts on the alcohol stability of the imita- tion milks, various quantities of 0.25 M CaCl2 solution were added (See Table 4 and 5). For evaporated milk prepared by direct—formulation method, the addition of 0.02 ml of 0.25 M CaCl2 solution, and 0.01 ml to the second batch sample, caused coagulation, whereas the fluid-base imitation milk was coagulated by the addition of 0.01 ml. The lower amount of added CaCl2 which caused coagulation in the second batch specimen may be ascribed to the higher concentration of indigenous ionic calcium in the sample. The concentration of ionic calcium required to effect coagulation was found to be 0.22 mg per 2 ml (11 mg%) of the first batch sample and 0.11 mg per 2 mg (5.5 mg%) for the second batch sample of direct-formulation product. For the fluid—base product it was 0.11 mg (5.5 mg%) of ionic calcium. The results illustrate that a slight increase in calciun content will cause a positive reaction to the alcohol test. Presumably, calcium-caseinate-phosphate complex is sensitive to a change 32 Hosooam wo Lawnmhum 6:90 .HOUUNM COHUDHHU 05H mUwCHEHHO 0U ON: MO mUCDOF—w UCflMNWMHn—U xHHE mo HE N cu wonvm mums Naomo z mN.0 mo mcofiumhucoocoo ucwhmmmfinn mamfipu 03m.o + + + + + + + + + I I fins + + + + + + + + H I I Ufion HE H. 00.0 no.0 00.0 no.0 «0.0 no.0 No.0 H0.0 nm00.0. 0 Naomo 2m~.0 HE 0 H0.0 No.0 no.0 «0.0 00.0 50.0 00.0 00.0 m00.0 UH.0 0N: Auoavona cowumHDEMOMIuomMHQV umou Honooam mam co cofiuDHOm Homo mo uommmm .q canoe 33 Honooam mo nuwcmuum 6:90 wouomm :oHuDHwU onu oumcHEHHo ou om: mo mucsoEm acouommwoo xHHE mo #5 N on covom owoz NHomo : mm.o mo mcowumuucoocoo ucmuomonn mamfiuu 038m + + + + . + + + + + I I $05 + + + + + + + + + I I Ufiom N as H. 00.0 no.0 00.0 00.0 00.0 no.0 No.0 Ho.o nmoo.o o aomo ZmN.o HE o Ho.o No.0 no.0 00.0 00.0 50.0 00.0 00.0 000.0 0H.o 0N: Aboaemae measuraaeeo ammo Horoeae are :6 seamaaoa Home mo uaauwm .m weary 34 in calcium activity. Destabilizing this complex causes aggregation of the casein particle. The addition of Na-citrate to imitation evaporated milk did not cause coagulation and the alcohol test was negative. Citrate counteracts the action of calcium by decreasing the concentration of ionic calcium. The Binding of Ionic Calcium by Na-citrate From the results of previous tests, it was noted that a slight increase in calcium caused coagulation whereas the addition of citrate caused negative alcohol tests. Data in Table 6 show that 0.05 ml of 0.25 M CaCl which 2 rendered the alcohol test distinctly positive and caused coagulation in direct-formulation product was prevented by the addition of 0.2 ml of 0.25 M Na-citrate. The concentra- tion of Na—citrate which prevented the coagulation was found to be 14.6 mg per 0.5 mg of ionic calcium. The addition of 0.25 ml of 0.25 M Na—citrate to 2 ml of fluid-base product prevented the coagulation caused by 0.05 ml of 0.25 M CaCl2 (See Table 7), indicating that 18.25 mg of Na-citrate prevented the coagulation caused by 0.5 mg of ionic calcium. To determine the concentration of ionic calcium bound to citrate, 0.375 ml of 0.25 M CaCl2 was added to 15 ml of milk which made the alcohol test distinctly positive. To prevent the coagulation caused by ionic calcium, Na—citrate was added in concentration expected to counteract the action 35 Honooam mo zuwcoum 0:90 .xaae «6 as N 60 cream aea oumuuHoImz z m~.0 ocm «Homo z n~.o mo cofiumuuCoocoo uconMMHon .mHmHHu 039m I I I + + fine I I I + + axon HE om.o m~.o o~.o ma.o oH.o moaneaoIaz z n~.o HE no.0 mo.o mo.o no.0 amo.o Nauru z m~.o mfiuonvoua cowumHDEuom uomuaoo umou Hosooam mnu co mocmamnIuHmw mo uommmm one .0 oHan 36 Honooam mo nuowwum oseo xeae me as N an verve one; oumuuHoImz z 0N.0 0cm Naomo z m~.o mo mcowumuucoocoo ucopmmmwon mHmHHu 039m I I + + + fine I I + + + axon HE om.o m~.o o~.o ma.o oa.o abreaaaIez z mN.o N as no.0 no.0 no.0 no.0 a35 Homo z m~.o Auosoouo mmmnIUHDHmo umou Honooam onu co mocmHmnIuHmm mo uoomwm 059 .n manme 37 of ionic calcium. Data in Table 8 show that of the 10.75 mg of ionic calcium in direct—formulation product, 7.5 mg was determined as Ca+_+, indicating that 3.25 mg of ionic calcium was bound to citrate. For the second batch speci— men, 3.35 mg of ionic calcium was bound to citrate. In the fluid-base product, of the 12.75 mg of ionic calcium 9.2 mg was determined as Ca++, thus 3.55 mg of ionic calcium was bound to citrate and for the second batch 3.15 mg of ionic calcium was bound to citrate. The concentration of Na—citrate, which bound ionic calcium in direct—formu- lation product, 33.69 mg of sodium citrate per mg of ionic calcium for the first batch and 32.68 mg for the second batch. For the fluid-base product 36.70 mg of Na-citrate per mg of ionic calcium was required for the first batch and 41.36 mg of Na—citrate per mg of ionic calcium for the second batch. The above described experiments indicate that salts have an important influence (M1 alcohol stability. The effect of calcium, which cause a positive alcohol test, can be counteracted by the addition of citrate. The concentra- tion of sodium citrate required to prevent coagulation was different for each milk sample. Prediction and Control of Heat Stability with the Stabilizing Salt Test Sommer and Hart (1926) stated that heat stability was maximized at an optimum salt—balance. When this optimum salt-balance disturbed, evaporated milk was less heat stable. 38 .HOm oU6HuHoI6z 066 .Hom NH060 mo coHquo6 onu H6uM6 EDHoH6o UHCOH mo assoe6 6:86 .GOHuH606 3:6 whommn EDHoH6o oHcoH mo uCDoE6 6:90 .xHHm me as ma 60 66666 Same aaoa>aee mnu Eouw xHuocHumHo coHu6H306oo vom56o soan H060 2 m~.o mo aoHu6uuaoocoo osen .wH6Huu 0396 0.NH NH ~.o 05.0 m mn0.H 050.0 uoaoouo om6nI6HnHm 0.0 o 60.“ mn.m on m.H amnm.o uosoowo coHu6HDEuo0IuoouHm 66066 @6666 HE N HE uonvoum oocHEuouoo 02 HE 00H\0z ou6HuHoI6z .Ho6o ++6o ++6o ++6o 2 00.0 2 n~.0 ou6HUHo ou vason ESHoH6o oHCoH mo coHu6Hucmwcoo one .0 6H06H 39 To determine the proper amount of stabilizer, disodium phosphate was added to imitation evaporated milks in dif- ferent concentrations (See Table 9). The first sample represents the direct-formulation product withcut any salt addition. The second represents the same milk in dilution form to compensate for the dilution factor. The dilution rate was the same in all the milk samples. Data in Table 9 show that there was no coagulation in any of the samples, but by increasing the addition of 10% disodium phosphate the color became darker in the sterilized product. Color development was minimal for the control sample and was only slightly darker than the color of commercially—processed, filled evaporated milk. Ad- dition of 0.10 ml and 0.15 ml of the phosphate solution caused increased color development. The sample to which 0.2 ml of 10% NaHPO4 had been added developed the darkest color. In the United States, the addition of stabilizing salt to the extent of 0.1 percent by weight to evaporated milk has been legalized and is equivalent to the sample containing 0.005 ml of 10% NazHPO4 in this experiment. Additionally, the viscosity was increased by increasing the concentration of disodium phosophate. Even though the viscosity was increased, it approximated commercial evaporated milk which showed a 27.5 sec. flow time at 24°C (75°F). The direct-formulation product to which 0.005 ml and 0.01 ml of 10% NaZHPO4 had been added had 40 1.666 m.k~o meme 06 xaae omu6hoa6>m omHHHm oommmooualeHmHohmEEoo nuH3 COth6ano up 06u3m665 663 huHmoomH>U A++o xHHE ©6u6uou6>o ooHHHm 06mm600hathH6HouoEEoo nuH3 mHH6amH> ©6u6oEoo 663 poHooo .aae ma\eoma~ be eaaaaaaeaa use xaae we as m on 66666 aoezNaz Hoa mo coauaaocmucoo oceeammann .mH6HHu o3u mo 606H6>6 6:96 om 0H.0N 0N 0.NN 0n.- 0N.NN 0.5N 0.n~ Hom$ 0%UHwoomH> +++++ _++++ ++++ +++ +++ +++ +++ +++ ouoHoo III III III III III III III III GOHU6H306oo N.o 0H.o oH.0 00.0 Ho.o 0000.0 0 o H8 dommm6z NoH o 00.0 oH.0 NH.o oH.0 00H.0 «.0 o HE 0N: 6 uosoowo :oHu6HDEwom uoowHo co ou6£omona 55.200620 mo uoowmo one .0 6Hn6e 41 a viscosity very close to commercially-processed, filled evaporated milk. Data in Table 10 indicate that none of the samples showed coagulation. Color was increased by increasing the quality of NazHPO4 solution. For samples ranging from no addition to 0.01 ml of 10% Na HPO4 stabilizer, the 2 color was slightly darker than that of commercial evapo— rated milk. The addition of 0.08 ml, 0.10 ml and 0.15 ml of 10% NazHPO4 yielded essentially identical color but were darker than the commercial specimen. The highest concentration of added disodium phosphate (0.2 ml) yielded the darkest color. There was no noticable difference in viscosity between fluid-base and the direct-formulation products. However, the fluid-base product was somewhat higher. This behavior was ascribed to a slight increase in total solids or, perhaps, to an increase in the caseinate-phosphate par- ticles. The fluid-base product has total solids of 26.53% compared to the direct-formulation product which con- tained 26.26% total solids. Thus, the principle problem encountered was the slight increase in brown color. Data in Table 11 show the effect of disodium phosphate on the coagulation time of the fluid-base product. Samples to which disodium phosphate solution had not been added were coagulated in 8 min., 50 sec., whereas the coagulation time of all other samples exceeded 15 minutes. By in- creasing the concentration of the stabilizer to 0.2 ml, 42 omu6poo6>o voHHHm vowmmoouoI0HH6HomeEoo LuH3 COmHu6oEoo >0 06H56665 663 qumoomH> lama m.a~6 acme be 6665 6 A++o xHHE owu6uoo6>6 voHHHm vommooopoleH6Hoperoo nuH3 xHH6st> 06660500 663 uoHooo 66 6666360666 666 xaae 66 He m .662 AH\aome~ 66 66666 aoexuaz $63 66 aoaeaauceocoe 6660666666 .mH6Huu o3u mo 606u6>6 6:96 6.6m n.6N 6.66 6.6N H.6N 6.~N m.a~ 6.6 6a6666663> +++++ ++++ ++++ ++++ +++ +++ +++ +++ UHOHOU III III III III III III III III fioHu6H306oo 6.6 63.6 63.6 66.6 a6.6 6666.6 6 ,6‘ He aoemuaz $63 6 66.6 6H.6 Na.6 6H.6 66H.6 ~.6 6 He 66: m nonvouo 666DIUHDHM co mU6nomOLQ ESHoOmHU mo uomwmo one .oH 6Hn6H 43 .mouncHE 0H\m o- u6 coNHHHuoum 6G6 xHHE mo HE 0 on 06006 6&63 6665060 0 ESHUomHv NoH mo wcoHu6uucoocoo ucoquMHon .mH6HHu o3u mo 606u6>6 6:96 o0 6H N.o o 0N 0H 0H.o 00.0 00 0 H.o H.o o 6 00.0 0H.0 A.CHE 0H C6£u mmoHo 00. 0 o «.0 .066 .cHE HE 600=N6z HE 0N: oEHu :oHu6H506oo uosvoua 666045450 00 66.3 coHu6H=06oo on“. com: 6m6£omono ESHcomHo mo 66:3086 06H0u6> H6coHuHoo6 mo uoommo 659 .HH oHn6H 44 coagulation time was increased. For the direct-formulation product there was no difference in the coagulation behavior except that the coagulation time was longer than that for the fluid-base product (See Table 12). There was a two minute difference for the direct-formulation product in the lowest concentration of 10% NazHPO4 (0.05 ml), which is equivalent to a 5 mg addition of stabilizer. Addition of 0.2 ml (20 mg) of stabilizer salt increased the coagulation time to 35 min., 50 sec. minutes and was longer than that for the fluid—base product by 6.0 minutes. Therefore, in both types of imitation evaporated milks, optimum addition of disodium phosphate had the effect of stabilizing them against coagulation by sterili— zation. Data in Table 13 show the effect of CaCl2 on coagula- tion time of the fluid—base product. The coagulation time was decreased by increasing additions of 0.25 M CaCl2 solution. For the first sample, to which no CaCl2 was added, the coagulation time was 7 minutes. The addition of 0.005 ml of 0.25 M CaCl2 (equivalent to 0.05 mg of CaClz) decreased the coagulation time by one minute. The highest addition of 0.25 M CaCl2 (0.1 ml; equivalent to 1.10 mg of CaClz) decreased coagulation time to 2 min., 50 sec. As shown in Table 14, the addition of 0.25 M CaCl2 to the direct-formulation product decreased the coagulation time. The highest concentration (0.1 ml; equivalent to 1.10 mg of CaClZ) decreased the coagulation 45 .CHE 0H\m ohm D6 UmNHHHuoum 0:6 xHHE 00 He 0 ou 66066 6u63 ou6£amo a enHvoch on mo maoHu6pucmocoo ucmquMHan .mH6ku 036 no 606p6>6 6:96 66 66 ~.6 6 66 66 66.6 66.6 6 6 6.6 6.6 6 6 66.6 66.6 6:65 66 6666 66666 66 66 6 6.6 .oom .cHE HE HE 6666 66666666666 amom~6z 666 6N: uosoouo coHu6HDEw00IuoouH6 mo oeHu :oHu6H306oo oMu coo: mU6£owona EDH0o6 I26 00 665556 0cH>u6> H6coHuHEo6 mo uoommo 659 .NH oHn6e 46 .660 6a\e 64m 66 6666660666 6:6 6666 66 He 6 OH UUUUM 0H0?» HUGO ”— WN. MO mCOHUNHUd—QUCOO UCflHmHMHn—n— .mH6ku o3u mo 606uo>6 65H6 66 N 6.6 6 66 6 66.6 66.6 6 a 66.6 66.6 6 6 666.6 666.6 6 a 6 6.6 .066 .CHE HE HE 6566 66666666666 66666 2 66.6 66: uoaooue 666LIUHDHM mo 95”. 6936160600 606 com: N$6060 mo uoommm one .MH 3060. 47 .6666: 66\e 6am 66 6666666666 6:6 6666 66 He 6 Cu Umvfium QHG3 HOMO cw WNoo MO mCOHUmHUCwUCOU UCQIHmMMHn—fl .mH6Hhu o3u mo 606w6>6 6:96 00 m H.o 0 0 0 00.0 00.0 00 0 H0.o 00.0 0 6 000.0 000.0 0 0 0 H.0 .oom .CHE HE HE oeHu coHu6H306oo NH060 z 0N.0 0N: uosvon :oHu6HDEquIuoowHU 6Com: H060 mo uomwmo 9.3. .6H 6Hn6e mo mEHu coHu6H506oo 6:» 48 time to 3 min., 50 sec. At the same concentration of CaClZ, the direct-formulation product exhibited a longer coagulation time than the fluid-base product. Thus, the latter product possess a lower heat stability. Casein exists as complex particles or micelles con- taining citrate, inorganic phosphate and calcium. Many problems associated with heat-treated dairy products depend on the behavior of this system. The caseinate particles are very sensitive to ionic calcium which causes coagula- tion. Whereas citrate and phosphate exert an opposite action to that of calcium because they decrease the effect of calcium concentration. It would be expected that the concentration of ionic calcium and phosphate in milk would be decreased by heat treatment because calcium phosphate is less soluble at high temperatures (Jenness and Patton, 1959C). From the result obtained with the salt test, one observes that the heat stability was decreased by increasing the concentration of total milk solids. This behavior is attributed to the in- crease in destabilizing ions (i.e. Ca++). Furthermore, it was shown that an increase in heat treatment or calcium ions decreased the heat stability of the concentrated milk. Increased heat stability of the caseinate system is achieved not only by the addition of phosphate or citrate salt. Some evaporated milk is stabilized by the addition of calcium and destabilized by the addition of citrate or phosphate (Sommer and Hart, 1926). This atypical behavior is 49 attributed to a distortion in the salt balance of milk. If this phenomenon is due to an excess of phosphate or citrate, it can be prevented by adding the proper amount of calcium chloride or by an increase in acidity. This procedure changes secondary phosphate to primary phosphate which have a little or no effect on salt balance (Hunziker, 1949). On the other hand, if heat instability is due to an excess of calcium, appropriate amounts of disodium phosphate or sodium citrate will assist in preventing heat coagulation. Therefore an excess of either citrate, phosphate or calcium can cause coagulation. Thus, a salt test is needed to find the type and amount of salt to be used. Forewarming Effect on the Heat Stability of Imifation Evaporated“Milk Forewarming is one of the most important steps in the manufacture of evaporated milk from the heat stability point of view. Data in Table 15 show that for the direct— formulation product there was a difference in coagulation time. Compared with the product forewarmed to 93.500 (200°F) for 10 minutes, there were 4 min., 25 sec. less for coagulation time for the product sterilzed without a forewarming treatment, and 2 min., 45 sec. less for the product which forewarmed to 87.5°C (190°F) for 5 minutes. For the fluid—base product, there were 4 min., 10 sec. in coagulation time for the product without forewarming treatments, and one min., 85 sec. for the product which 50 .6H6Huu o3u mo 606um>6 6:96 IH 0 0H 00m 0m 0 0 00H 0 q 05H8H63ouom usonuH3 uoavoum 666nI6H=Hm 00 0 0H 00m 0H 66 0 00H uoaoouo 00 0 wcHEh63ouom uDoLUHz coHu6H=EquIuomuH0 .oom .cHE ACHEV ousu6wmoeme mocha mEHH uosooum uoavoum u6 mEHu coHu6H506oo 0cHEh63oHom mxHHE 66u6uoo6>6 coHu6uHEH mo muHHHn6um u6o£ co 6:65u6ouu wcHEu63ouom mo mucosHmcH 65H .0H 6Hn6H 51 preheated to 87.50C (190°F) for five minutes. Comparing the results in Table 15 with those in Table 11 and 12, one observes that by diluting the sample with 4% water the heat coagulation time was increased. The fluid-base product increased in coagulation time by 40 sec., whereas for the direct-formulation product it was 35 sec. When imitation evaporated milk is not forewarmed, or when a low temperature preheat treatment is used, it will coagu- late more readily when sterilized. Sommer (1923) explained that the albumin content of milk has an effect upon the coagulation. Since albumin is precipitated by forewarming, the heat stability of evaporated milk is increased by this process. Additionally, the forewarming process decreased heat coagulation by pre— cipitating some of the soluble calcium as calcium phosphate. Forewarming improves the heat stability and viscosity and can be a factor in color development and flavor of evaporated milk. In general, temperatures from 93.5°C (200°F) to the boiling point for 5 to 10 minutes are em- ployed in the manufacture of evaporated milk. Time and temperature depend on the seasonal factor, the concentration of evaporated milk, and the method of forewarming. The Effect of Selected Substances,ng and CaCl2 Solution on the Development of Brown Discoloration The prolonged heat treatment of evaporated milk, as in the sterilization process, caused an increased discolora- tion.i31 the finished product. Stalberg and Radaeva (1966) 52 studied this problem and recommended using selected sub- stances to minimize or prevent this discoloration. Addition of 0.01 ml of 10% ascorbic acid solution to 10 ml of direct-formulation product gave a color similar to that of commercially-processed, filled evaporated milk (See Table 16). This is equal to 10 mg of ascorbic acid per 100 ml of evaporated milk. For the fluid—base product the addition of 0.015 ml, 0.02 ml and 0.025 ml of 10% ascorbic acid gave a color closer to that of filled evaporated milk. Thus, fluid-base product requires a larger addition of ascorbic acid than direct-formulation product. This behavior may be ascribed to a slight increase in the lactose content of the fluid- base product. Addition of 15-25 mg % of ascorbic acid may help to reduce the brown color in the fluid-base products. Evaporated milk exhibits a darker color than whole milk. Addition of more than 15 mg of ascorbic acid to 100 ml of direct-formulation product and 25 mg to 100 ml of fluid—base product produced a whiter product than the normal color of evaporated milk. On the other hand, the addition of less than 10 mg of ascorbic acid to 100 m1 of the direct- formulation product and 15 mg of ascorbic acid to 100 ml of the fluid-base intensified the brown color. Data in Table 17 show that the addition of sodium hexa- metaphosphate (10-20 mg/100 ml of evaporated milk) eliminated the browning in the direct-formulation product, whereas 0.015-0.02 ml of 10% sodium hexametaphosphate (15-20 53 .I+++6 666e 0006M006>0 vaHHw ommmmoouoIhHH6Hopmeeoo nuH3 mHH6DmH> 00h6oeoo 663 uoHooo .XHHE MO HE OH OH mummvmvm 0903 UHUG UHDHOUmQ ARCH MO COHUQHUCflUCOU UCflHQNNHQ n .mH6HHu 0396 ++ +++ +++ +++ ++++ ++++ ++++ uonooua 066DI0HDHh ++ ++ ++ +++ +++ ++++ ++++ 0000060 0 :0Hu6H38hom uomuHQ HE 00.0 0N0.o No.0 0Ho.o Ho.o D000.o 0 0H06 oHnuoom< on 0 000.0 Ho.o 0Ho.o No.0 0No.o 00.0 HE oNx mxHHE 0006H006>0 coHu6uHEH mo wcHC3own mnu co 0Ho6 UHDHOm6 no 006006 659 .0H oHn69 54 .A+++o xHHE 00066006>0 00HHH0 ommmmoouoIzHH6HoumeEoo cuH3 MHH6an> 00H6oEo0 063 uoHooo XHHE MO HE OH OH Ummumvm 0903 0UM£QNUGEN$¢£ EHHHUOW o\oO.—.. MO mCOHUQHUCUUCOO UCNHGWNHQ n mH6HHu 0396 0030000 ++ ++ +++ +++ ++++ +++++ +++++ 0660I0H5Hm 0050000 ++ ++ +++ +++ +++ ++++ 0++++ :oHu6HDEwom uuouHa I HE 00.0 0N0.0 No.0 0Ho.o Ho.o 0000.0 0 006£000£0600§6X0£ esHvom fioH 0 000.0 Ho.0 0Ho.0 No.0 0~o.o no.0 He 0 mxHHE 00060006>0 coHu6uHEH mo 00H53oun 050 so 006£omoco6wme6x0£ EDHvom 00 000000 059 .NH 0Hn69 55 mg/100 ml of eNaporated milk) prevented the brown color in the fluid-base product. Less than 10 mg/100 ml caused discoloration and more than 20 mg/100 ml for both types of milk yield a whiter color than commercially-processed,filled evaporated milk. Stalberg and Radaeva (1966) found that the addition of 0.01 percent of vitamin A, 0.15 percent of glucose oxidase, 0.1 percent of ascorbic acid and 0.15 percent of sodium hexametaphosphate to the sweetened condensed milk inhibited the formation of brown color. They also found that the amino-sugar reaction proceeded at a slower rate when compared with control samples. Comparing the results in Table 16 and 17 with the results of Stalberg and Radaeva (1966), demonstrate that there is similarity for the amount of ascorbic acid (10—15 mg) which was added to 100 m1 of direct—formulation product. For fluid-base product, the amount of ascorbic acid was 15 mg/100 ml of evaporated milk which was higher than the level recommended by Stalberg and Radaeva. However, for sodium hexametaphosphate, 10 mg/100 ml of direct-formulation product, was less than the amount used by Stalberg and Radeva. For the fluid-base product, both results were the same; 15 mg/100 ml of evaporated milk. In general the following conclusions may be drawn. 10 mg of ascorbic acid or 10 mg of sodium hexametaphosphate per 100 ml of direct-formulation product is effective in preventing the borwn color. For the fluid-base product, 15 mg of ascorbic acid or 15 mg of sodium hexametaphosphate 56 per 100 ml of milk effectively inhibited discoloration. Data in Table 18 show the effect of pH on the browning of imitation evaporated ndjju All samples for both types of milk exhibited brown color. At higher pH levels (7.0 7.2), discoloration increased in both types of imitation evaporated milk. Within the pH range of 6.60-6.70, the color was slightly darker than commercially-processed, filled evaporated milk. Addition of 15 mg of sodium hexa- phosphate per 100 ml of milk did not produce a change in the pH (i.e. 6.70) of imitation evaporated milk, whereas the addition of 10 mg of disodium phosphate per 100 ml of milk caused an increase in pH to 6.74. Presumably, this increase in pH was a contributing factor in color formation. Data in Table 19 show the effect of added CaCl2 solu- tion (Hi the browning of imfltation evaporated milks. The addition of 0.25 M CaCl2 to imitation evaporated milks did not promote discoloration. There was no difference in color with or without addition of CaClz. Thus, calcium is not a factor effecting browning in imitation evaporated milk. Certainly, the time and temperature of sterilization are important factors which contribute significantly to the formation of brown color. Thus, evaporated milk should be cooled immediately after the sterilization process. Other- wise milk will be exposed to excessive heat which will increase the formation of brown color. 57 .A+++o.xHHE 00060006>0 00HHHw 00mm0oou0ImHH6Hou0EEo0 50H3 >HH6DmH> 00060500 663 uoHooo. .m0uscHE 0H wow u 000 06 00NHHHu0um 666 6662 66 He 6 66 6662 66\z 666 66: 66\z 66 66666666 06 66666666 663 :66 .mH6Hhu 030 mo 006u0>6 0:96 +++++ +++++ 0N.n +++++ +++++ 00.9 ++++ ++++ 09.0 ++++ ++++ 00.0 ++++ ++++ . 00.0 ++++ ++++ 000.0 0uoHoo :0 6030000 0m60I0HDH0 00:00H0I:0Hu6HDEHOMIuo0HH0 6 mxHHE 00066006>0 00Hu6uHEH mo wcHC3ohn 0:0 :0 :0 no 000000 .0H 0Hn69 .A+++o xHHE 00060006>0 00mm00000I9HH6H0005500 £0H3 9HH656H> 00060500 663 00H000 .0030000 0m60I0HaH0 00 000 .0000000 60H06H58000 0000H0 00 000 .CHE 0H\o 00m 06 .8 00NHHHH006 0:6 xHHE 00 HE 0 00 00006 0003 NH060 z 0N.o 00 0000600000000 00w0000H00 5 .mH6Hu0 030 00 006H0>6 0096 uoHoo 0050000 ++++ ++++ ++++ ++++ ++++ 0m6£I0H3H0 ++++ ++++ ++++ 0++++ ++++ 00H06Mwhmw0wwwwmmm N9.0\N9.0 0N9.0\0H9.0 09.0 09.0 09.0 =0 0600. o NHomo 2 mm. 000.0 o 00: 6 mxHHE 00060006>0 coH06uHEH 0o 00Hc3000 0:0 :0 NH060 00 000000 .0H 0H069 The Effect of Homogenization on the Emulsion of Imitation EVaporatedIMilk An emulsion consists of two ihmfiscible liquid phases. One is a dispersed phase and the other is a dispersing medium. The dispersed phase is known as the globular phase while the liquid surrounding the globules is known as the continuous phase (Clayton, 1935). Milk is an emulsion of the oil/water type in which the oil phase consists of fat globules and the water phase is the milk plasma. The process of reducing the globules to a small and approximately equal diameter is called homogeni- zation. By increasing the number of globules and decreasing their size, the stability of an emulsion will increase. As a result, globular separation will be prevented and a uniform emulsion system will be obtained. The size of fat globules in the fluid-base product was 3—4 0, whereas in the direct—formulation product fat globules size were 2-3 u (See Figure 4a and b). The size of fat globules of commercially-processed, evaporated milk was about 2 I1(See Figure 40). One observes that the emul- sion system of the direct-formulation product approximated that of commercially-processed, evaporated milk. Thus, there was no obvious tendency for the fat globules in imita- tion evaporated milk to form clusters or fat separation. The effect of heat treatment on the emulsion system is shown in Figure 5 a, b. In both products, the emulsion system was disturbed (larger fat globules) and the casein- ate phosphate micelles aggregated. 59 - ~Du h— 6.6 . A c. ‘ l.‘ I, 1‘ ' - . 05> 5. K” . .3 (M. l b) direct formulation product, and c) commercially processed evaporated milk (100x magnification) Photomicrographs of a) fluid—base product Figure 4. 61 16666666666666 .66666 06 0H0 0050000 :0006H5E000 m00hH0 A6 00 m0H0E6m 0006H50600 060: 00 6:06 awng. I ”“6460 .6, .6 .6av.§kfi%fi . b . .KFNM. 640% 66w? 0.0. I 0.0.0.6610”: . .6. If t. .D‘ O fikfi ...6I60066 .66.. 6.66, ”Nahumawn66.umwnfiriI . dvyv . r o . Mum." “re-irks: T. .fiw.wflax. 666 66 .666 66 6666666 6666I66666 06 666 lemmam 66 .666 ouoHEouo£0 w .0 0050H0 Sensory Evaluation of Imitation Evaporated Milk Sensory evaluation is an important part of the process— ing and development of new milk products. The method employed to evaluate the imitation milks developed in the study consisted of a performance survey in which there were ten participants. This number of participants was too low for extended statistical analysis but large enough to pro- vide a "working" opinion about the products which were pro- duced. Data in Table 20 show the results of this evaluation. By using the analysis of variance there was no significant difference between any of the comparisons at 95% level. The color in all samples was acceptable. For the fluid-base product, samples from 2-4 were similar to each other. The addition of sodium hexametaphosphate to 15 mg/100 milk (sample no. 4) increased the acceptance of the color, flavor, mouth feel, and odor over the commercially—pro— cessed, filled evaporated milk. For direct-formulation product, samples from 5 to 7 were less acceptable in flavor and body. Compared to the commercially-processed, filled evaporated milk, the color, mouth feel, and odor were good. In general the fluid-base method would be better for the manufacturing of imitation evaporated milk that the direct—formulation method. However, the direct-formulation method produced a product possessing better heat stability and a lighter color when sodium hexametaphosphate or as— corbic acid were not added. However, the defects encountered 62 63 .603H6> 0606 0:90 .H0>0H N00 06 60060060500 000 00 936 0003000 00300000H0 036000chHm 00 663 00000 0036H06> 00 mHmzH636 050 03063 906 .006006000600E6x0n E3H0om 00H\0E 0.H 5003 0030000 00006H3eo00 000000 .9 .006000000600E6X00 E30000 00H\0E 0.9 £003 0030000 :0006H3E000 000000 .0 .00600600060056000 00 00000006 0300003 0030000 30006H3E0o0 000000 .0 .00600600060066000 E30006 660\66 66 6663 6666606 6666I66660 .6 .00600605060056000 E30006 00H\0E 0.9 00 60060606 6603 0030000 0660I00300 .m .00600600060056000 530006 66 66660666 6666603 6666606 6666I66660 .0 .6666 00060006>0 00HHH0 006600000 0HH60000EE00 .H 0.0 0.0 9.0 0.0 H.0 9 0.0 N.0 0.0 N.0 0.0 0 0.0 N.0 0.0 H.0 0.0 0 0.0 0.0 0.0 0.0 0.0 0 0.0 0.6 0.0 0.0 9.0 m 0.0 0.0 0.0 0.0 N.0 N 0.0 0.0 0.0 0.0 00.0 H 0000600 .0000860 000000 0030000 0000 0:0H000 £030: 00>6H0 H63mH> 0oHoo 0H0E6m 6mxHHE 00060006>0 000060H50 00 000063H6>0 9006000 .0N 0H069 64 in the fluid-base product can be lessened by the addition of stabilizing salts to prevent coagulation and sodium hexametaphosphate or ascorbic acid to reduce the brown colon Data in Table 21 show the properties of imitation evaporated milk produced by both methods compared to those of commercially—processed, evaporated milk and filled, commercially-processed evaporated milk. As indicated, the total solids in fluid-base and direct formulation products were higher than that of commercially— processed, evaporated milks. The viscosity of the imitation evaporated milk was less than that of the commercially- processed, filled evaporated milk. This property may be due tn) the addition of carrageenan and disodium phosphate to the commercially-processed, filled evaporated milk. Only sodium hexametaphosphate was added to the imitation evaporated milks. Ionic calcium as a major factor in the heat coagulation of evaporated milk was less in imitation evaporated milk than in the commercially-processed milks and this may increase the heat stability of imitation type of product. Experimental Imitation Evaporated Milk - CommerCialiniaIs Imitation evaporated milk was manufactured under com— mercial conditions, using soybean oil, isoelectric casein, water, and demineralized whey solids as ingredients. By decreasing the amount of demineralization whey solids, there was an increase in ionic calciun and in viscosity (See Table 22) . 65 0.9N N0 0.0m 0m 000 009\HE m 00000000> 00 00 0 0 0e OO0\0e 5300000 00000 mm mm mm mm 05 OO0\0e 5300000 00009 00.0w 00.0w 0N.0N 00.0m NmH x005 x005 00000000>0 00000000>0 000000 0030000 0030000 00000000 000000000 . 000000000 00000035000 000000050 000000005500 000000005500 000000 0000300300 00000000>0 000000000 000000005500 000 00000000>0 0&005 000000050 00 0000000000 .00 00000 66 .00000 003 0000000000 0000 000000 0 00 0500 0080 .0003 0003 000000 00 #0 000 000000 0003 0000000000500 Nma.m0 0000 0000X0 0 00 0500 0090 .0003 0003 00000 0000000000 oz .0000000000 .000000 .000 00m 00 00000000500 000 00000 0003 000000 0003 0000000000500 Nm0 .AOOm.N\om0v 0 000 00 00000000500 000 00000 003 000.00 000 00m.000N0 00 000000000 530000 0003 000m3 00 00000>000 003 000.~0 0000000 000 000 0.00 00 000 0000\05 m 00000000> 00 00 om.M0 m 0000\050 5300000 00000 00 00 00 00 AooH\0ev 5200000 00000 00.00 00.00 O0.0~ 00.00 000 000N0\00 000\O0 w0\w 0\0 00000000 .000000 on 0000000000 0 0 00000 w0m 00000 0:0 00000 000 0 000009 0000005500 II 0005 00000000>0 000000050 0000050000x0 00 0000000000 0000000m .mm 00008 67 The addition of stabilizing salts to sample from the third trial decreased the ionic calcium, so that the viscosity of that product was less than that of the same batch but without any additional stabilizer. The amount of demineralized whey solids in the second and third trials were similar. However, the viscosities were different. This increase in apparent viscosity was attributed to the effects of the higher activity of calcium ions. One indication of this is that the addition of stabilizing salts decreased the amount of ionic calcium, and thus decreased the viscosity. Although the second trial sample had higher amounts of ionic calcium than that of the third trial sample with added stabilizer, its viscosity was less. This may be ascribed to the increase in total solids in the third trial. All of the experimental samples exhibited some degree of browning, but compared to the trial with deionized (lower calcium) whey solids, there was a noticable improvement. Deionized whey (sodium zeolite) increased the browning color, viscosity and salty flavor. Data in Table 23 show that the viscosity was decreased by increasing the amount of ionic calcium in sample No. 8 of the fifth trial series. Also its viscosity was very high. Possibly, the calcium—casein combination was not at its optimum level. The increase in total solids from the fourth to the fifth trial was regarded as the cause for the increase 68 .wcofiumwucmocoo ucmumMMHU cw coHuSHom Naomu mo Show msu Cw boobs .cmvnm was iao.mv Hao mm3 A#mn.ov mos: ooNHwaoCHEma was sawoamo owcoH new .omaooo .oom um omnwcowoeos cam omma Ou woumon .owoom .Aoomm\oomv um sumacmmoeos .momma ou cmumm: .Iomz cam cowamo .ONI cogs wouum>coo mos A#o.mv cfiommos No He m.¢o ma me an an an mm summooma> Aoofi\mec om am am NN ma m.oa m.oH m.o m.m endgame oacoH iooH\wec mm mm we as mm an em m.H~ as eaaoamo Hmuoe am am am an an a.- a.- a.N~ o.a~ ems em.as Ha.qm mm.oq mo.wm ~a.om aa.m~ o¢.mfi mn.a o supmaopm cocoa Eswoamo owcoa HE ooH\wE w a o s m N a o «amass sum lawns“ nus mHmHuH HmHoumEEoo xHHE omumw0dm>m cowumuwsw Hmucmefiwoaxo mo moauumaoua oouooaom .mm manmh 69 in viscosity; Calgon (hexametaphosphate) was added to the fourth and fifth trials, but without effecting the tendency to discolor. In evaporated milk, heat treatment is the most important factor effecting the browning reaction and the rate of formation brown pigmentation. Total solids content shouLd be the same as the legal standard (25.97.) because increasing the total solids in- creases the viscosity and the potential for development of color. Forewarming is an important step in the manufacture of evaporated milk, and one observes that in this study none of the milk samples were forewarmed. In addition to that, the use of 12.95% demineralized whey solids increases lactose content, and thus increases the potential for the browning reaction to occur. Therefore, using 107. or less of mineralized whey or sweet whey and 0.157. Calgon or ascorbic acid may help in reducing the formation of color. Dissolving casein with KOH and NaOH (4:1) will help in reducing the salty flavor. The addition of whey and calcium or appropriate stabilizer salts before homogeniza- tion might also give a better emulsion system and improved viscosity. CONCLUSION The stability of imitation evaporated milk manufactured by the direct-formulation method and the fluid-base evapora- tion method were found to be affected by the addition of calcium, phosphate and citrate ions. Forewarming increased the heat coagulation time for products produced by both methods. The heat coagulation time of the direct—formulation product was greater than that of the fluid-base product. The evaporative concentra— tion process employed to produce the fluid-base product enhanced the flavor, body and mouth feel of the sterilized product. 70 BIBLIOGRAPHY BIBLIOGRAPHY Alyar, K.R. (1969) Artifical milk as basis for research. New Zealand J. Dairy Tech. 4(1): 11-13. Ayer, 8.11. and Johnson, W.T. (1915) The alcohol test in relation to milk. U.S. Dep. of Ag. Bull. 202: 1-34. Bell, R.W., Curran, H.R. and Evans, F.R. (1944) Effects of temperature and time of steril ization upon properties of evaporated milk. J. Dairy Sci. 27: 913-919. Bell, R.W. and Webb, B.H. (1943) Relationship between high temperature forewarming and the color and heat stability of evaporated milk of different solids content. J. Dairy Sci. 26: 579—585. Benton, A.G. and Albery H.G. (1926) Studies on the stability of evaporated milk during sterilization with reference to the hydrogen in concentration, alcohol test, and addition of scientific buffers. J. Biol. Chem. 68: 251— 263. Clayton, VL Theory of Emulsion and Their Technical Treat- ment. Published by Blakiston's Son & Co., Inc. Phila- delphia, 3rd Ed. p. 2. Dahlberg, A.O. and Garner, H.S. (1921) The alcohol test as a means of determining the quality of milk for con— denseries. U.S. Dep. of Ag. Bull. 1944: 1-13. DeMan, J.M. and Batra, S.C. (1964) Effect of certain salts on the stability of skim milk as determined by rennet coagulation time and alcohol test. J. Dairy Sci. 47: 954-957. Dellamonica, E.S., Cusler, J.H., and Zittle, C.A. (1958) Effect of calcium chloride and heat on solutions of mix- tures of B—lactoglobulin and casein. J. Dairy Sci. 41: 465-471. Deysher, E.F., Webb, B.H., and Holm, G.E. (1929) The rela- tions of temperature and time of forewarming of milk to the heat stability of its evaporated product. J. Dairy Sci. 12: 80-89. 71 72 DeJongh, M. (1978) Effect of solids not fat, fat, and homogenization pressure on the heat stability of recom- mended evaporated milk. New Zealand J. Dairy Sci. Tech. (13) p. 242. deWit, J.N. (1981) Structure and functional behavior of whey. Neth. Milk Dairy J. 35: 47-64. Evenhuis, N. and DeVries, Th.R. (1957a) The condition of calcium phosphate in milk. Neth. Milk Dairy J . 11(2): 111-121. Evenhuis, N. and DeVries, Th. R. (1957b) The condition of calcium phosphate in milk. Neth. Milk Dairy J. 11: 213-224. Evenhuis, N. (1957) The heat stability of milk. Neth. Milk Dairy J. 11: 225—243. Griffin, A.T., Hickey, M.W. and Chandler, G. (1976) The significance of preheat and pH adjustment in the manu- facture of recombined evaporated milk. Aust. J. Dairy Technol. 31(4): 134-137. Holm, G.E., Webb, B.H. and Deysher, E.F. (1932) The heat coagulation of milk. J. Dairy Sci. 15: 331-343. Horne, D.S. and Parker, T.G. (1981) Factors affecting the ethanol stability of bovine milk. J. Dairy Res. 48: 273-284. Hunziker, O.F. (1949a) Condensed Milk and Milk Powder. Published by the author, La Grange, Illinois. 7th Ed. p. 276. Hunziker, O.F. (1949b) Condensed Milk and Milk Powder. Published by the author, La Grange, Illinois. 7th Ed. p. 225.. Hunziker, O.F. (1949c) Condensed Milk and Milk Powder. Published by the author, LaGrange, Illinois. 7th Ed. p. 291. Jenness, R. and Patton, S. (1959a) Principles of Dairy Chemistry. Robert E. Krieger Publishing Company, Hunt- ington, N.Y. 2nd Ed. p. 347. Jenness, R. and Patton, S. (1959b) Principles of Dairy Chemistry. Robert E. Krieger Publishing Company, Hunt- ington, N.Y. 2nd Ed. p. 349. Jenness, R. and Patton, S. (1959c) Principles of Dairy Chemistry. Robert E. Krieger Publishing, Huntington, N.Y. 2nd Ed. p. 330. 73 Jenness, R. (1953) Titration of calcium and magnesium in milk and milk fractions with ethylenediamine tetraace- tate. Anal. Chem. 25: 966-969. Kieseker, F.G. (1982) Recombined evaporated milk. Inter— nat. Dairy Fed. Bull Document 142: 79-88. Lampert, L.M. (1975) Modern Dairy Products. Chemistry Pub- lishing Company, Inc., N.Y. 3rd Ed. p. 416. Maxcy, R.B. and Sommer, H.H. (1954) Fat separation in eva- porated milk. J. Dairy Sci. 37: 1061-1070. Millory, T.H. (1915) The reaction and calcium content of milk as factor in the coagulation process. Biochem. J. 9: 215-228. Newstead, D.F. and Baucke, A.G. (1983) Heat stability of recombined evaporated milk and reconstituted concentrated skim milk: effect of temperature and time of preheating. New Zealand J. Dairy Sci. Tech. 18: 1-11. Newstead, D.F., Conaghan, E.F., and Sanderson, W.B. (1976) Effect of whey protein concentration on the heat sta- bility of evaporated milk. New Zealand J. Dairy Sci. Tech. 11: 223-230. Newstead, D.F., and Conaghan, E.F. (1979) Studies on the induction of heat stability in evaporated milk by pre- heating. J. Dairy Res. 46: 387-391. Pearce, R.J. (1979) Heat stability in concentrated and non concentrated milks, the effect of area and B-lacto- globulin levels and the influence of preheating. J. Dairy Res. 46: 385—386. Rogers, L.A., Deysher, E.F. and Evans, F.R. (1921) The relation of acidity to the coagulation temperature of evaporated milk. J. Dairy Sci. 4: 294-309. Rose, D. (1961a) Variations in the heat and composition of milk from individual cows during lactation. J. Dairy Sci. 44: 430-441. Rose, D. (1961b) Factors affecting the pH sensitivity of the heat stability of milk from individual cows. J. Dairy Sci. 44: 1405-1413. Rose, D. (1962) Factors affecting the heat stability of milk. J. Dairy Sci. 45: 1305-1311. Seckles, L. and Smeet, W. (1948) Instability of milk due to an increase of calcium ions. Dairy Sci. Abstr. 9(3): 243. 74 Sommer, H.H. and Hart, E.B. (1919) The heat coagulation of milk. J. Biol. Chem. 40: 137-151. Sommer, H.H. and Hart, E.B. (1922) The heat coagulation of milk. J. Dairy Sci. 5: 525-543. Sommer, H.H. and Binney, T.H. (1923) A study of the factors that influence the coagulation of milk in the alcohol test. J. Dairy Sci. 6: 176-197. Sommer, H.H. (1923) The heat coagulation of milk. World's Dairy Congr. 2: 1241-1248. Sommer, H.H. and Hart E.B. (1926) Heat coagulation of milk. Univ. Wis. Agr. Exp. Station Res. Bull. 67: 1-47. Stalberg, S. and Radaeva, I. (1966) Effect of varoius sub- stances inhibiting melanoidino - formation in sweetened condensed milk. Internat. Dairy Congr. 17: 153-157. Sweetsur, A.W. and Muir, D.D. (1980) The use of permitted additives and heat treatment to optimize the heat sta- bility of skim milk and concentrated skim milk. J. Soc. Dairy Tech. 33(3): 101-105. Sweetsur, A.W. and Muir, D.D. (1982) Manipulation of the heat stability of homogenized concentrated milk. J. Soc. Dairy Tech. 35(4): 126-132. Webb, B.H. and Holm, G.R. (1930) Color of evaporated milk. J. Dairy Sci. 13: 25-39. Webb, B.H. (1935) Fundamentals of Dairy Science. Reinhold Publishing Corporation, N.Y. 2nd Ed. p. 208. Webb, B.H. and Bell, R.W. (1942) The effect of high tempera- ture short time forewarming of milk upon the heat sta- bility of its evaporated product. J. Dairy Sci. 25: 301- 311. White, J.C. and Davis, D.T. (1958) The relation between the chemical composition of milk and the stability of case- inate complex. J. Dairy Res. 25: 256-266. Zittle, C.A., Dellamonica, E.S., Ruddand, R.K. and Cluster, J.H. (1957) The binding of calcium ions by B-lactoglobu- lin both before and after aggregation by heating in the presence of calcium ions. J. Amer. Chem. Soc. 79: 4661-4665. Zittle, C.A. and Pepper, L. (1958) Influence of hydrogen andand calcium ion concentrations, temperature and other factors on the rate of aggregation of casein. J. Dairy Sci. 41: 1671-1682. 75 Zittle, C. (1969) Influence of heat on K-casein: Effect of a s casein and concentration of calcium chloride and sodium chloride. J. Dairy Sci. 52: 1356-1358. 3 E R I“ M I! U IIHNWU