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I N D U S T R I A L A N D ENGINEERING CHEMISTRY SAFETYAND FIRST AID
Every effort has been made to make the plant and safe for workmen as well as to minimize external odors. Mechanical ventilation is provided throughout. All fusion Dots, tanks, and exhausts which might emit caustic or obiectionable odors are covered and connected to a large fume duct. The fumes collected by this system are first scrubbed and then vented to the main boiler stack of the plant. A safety organization is maintained with proper equipment for treating all probable plant accidents. A physician is in
Vol. 16, No. 10
attendance during part of every day to treat accident cases and to conduct &rough physical examinations of all employees periodically. A unique feature of the safety organization of this plant is a safety inspector, whose sole duty it is to see that all unnecessary hazards are removed promptly. ACKNOWLEDGMENT The writer wishes to express his thanks for the assistance of officers of the Bakelite Corporation in securing the material for this article and for permission to publish it.
Antiscorbutic Potency of Whole-Milk Powder'j2 By G. W. Cavanaugh, R. A. Dutcher, and J. S. Hall CORNELL UNIVERSITY, ITHACA, N . Y., ANQ PENKSYLVANIA STATECOLLEGB, STATECOLLEGE, PA.
milks, we find that investiT IS well recognized The milk used in these experiments was obtainedfrom 1276 cows. gators are disagreed conthat the vitamin conI t was mixed, sampled, chilled, and portions were shipped daily i n cerning the relative values tent of milk and milk sterilized steel vacuum bottles. The balance of the milk. was conof various milk powders as products is influenced by a densed in a continuous steel evaporator and pasteurized in a closed a n t i s c o r b u t i c agents, alnumber of factors, the most glass-lined tank at 145" F. for 30 minutes, in the absence of air. though most of the workers important of which seem to The hot pasteurized evaporated milk was atomized under exceedingly contend that the process of be the diet of the COW^-^^* high pressure in a drying chamber where the milk dried instantamanufacture is the most and subsequent treatment neously, the powder being removed at intervals of 2 to 2.5 hours. i m p o r t a n t single factor. of the milk. Owing to the Samples of this powder were shipped daily, with corresponding Many investigators who fact that the importance of samples of fluid milk. have conducted experiments the dietary factor has been Several groups o j guinea pigs, ten to a group, were fed a basal using milk powders have recognized but compararation plus the experimental milks. The control groups developed failed to take into considtively recently, it has been scurvy in about 14 days, but were cured of the disease by the addition eration the age of the powdifficult to evaluate properly of fresh powdered orange and lemon juices, the latter having been der, the conditions of stormany of the investigations manufactured by the same process as the powdered milk. Other groups age, factory methods, or that have been conducted in which received the basal ration plus the fresh and powderedfruit the season of the year when the past with reference to juices from the beginning of the feeding period grew well and did the milk was produced. the vitamin content of cow's not develop scurvy. H e s s a n d co-workers* milk. This is particularly A comparison of growth curves, time of appearance of scurvy showed that milk did not true of the antiscorbutic symptoms, and post mortem appearance of guinea pigs showed lose its antiscorbutic properpotency of milk. For exremarkable similarity when raw and powdered milks werefed at the ties when manufactured by a m p l e , i n v e ~ t i g a t i o n s l ~ ~same ~ ~ level. No marked differences could be noted in the appearance the roller process. Other vary in their estimate of the and deportment of animals when the raw and powdered millip were investigator~g~~0~~1 have acamount of raw milk necesfed in equivalent amounts. cumulated considerable evisary to protect guinea pigs dence which has seemed to from scurw. the amounts show that many milk powders made by the spray process are ranging frok30 to 150 cc. Similarly, investigators have disagreed concerning the deficient in vitamin C. Johnson and Hooper'O pointed out that antiscorbutic potency of pasteurized, boiled, condensed, and one brand of milk powder, made under special conditions of powdered milks. I n the last-mentioned types of milk manufacture, possessed considerable antiscorbutic properties products, however, we are confronted by a number of other while other powders made by the same process were deficient. more or less baffling problems. For example, it is not yet These writers seem to be of the opinion that all drying procclear just how much importance can be attached to the usual esses are destructive unless particular care is taken in conmethods of pasteurization and heating. Some experiments6 trolling all stages in the process of manufacture. The present investigationt is the result of an attempt to have indicated that ordinary vat pasteurization possesses a destructive action, while others' seem to prove that pasteuriz- determine the influence of drying, by the spray process, on the ation of itself is less destructive than the subsequent storage. antiscorbutic properties of milk. The plan included a study While all workers are not agreed as to the magnitude of the of the raw whole milk, as it came to the factory, as compared destruction of vitamin C by heat, most of them seem to be with the powdered product. So far as the writers are aware, agreed that the elimination of chances for oxidation is neces- no work has been done on commercial milk powders where it sary and desirable. This idea was confirmed by Dutch& by was possible to study the raw whole milk a t the same time. It was thought that, if this could be done, it would bdpossible the pasteurization of milk in closed bottles. When we consider the work that has been done on powdered to obtain quantitative data regarding the destruction of vitamin C by heat and oxidation, if such destruction were 1 Received May 14, 1924. found to occur. 2 The work was conducted at Cornell University by G W. Cavanaugh
I
and J. S. Hall, Department of Agricultural Chemistry, and directed and supervised by R. A. Dutcher, of Pennsylvania State College. * Numbers in text refer to bibliograpby at end of article.
t
A portion of the expense of this investigation was defrayed by a grant from %e Merrell-Soule Company, J. S. Hall holding the Merrell-Soule Industrial Fellowship at Cornell University.
October, 1924
INDUSTRIAL A N D ENGINEERING CHEMISTRY
The raw milk used in the experiment was taken from mixed milk obtained from 175 dairies representing 1276 cows. The mixed milk was drawn from a large vat, chilled, and shipped daily to Cornel1 University in large, sterilized, steel vacuum bottles. Sufficient milk was shipped each day to suffice for 2 days of feeding in order to guard against the possibility of loss of milk in transit. The powdered milk samples made from the raw milk were shipped each day in a special shipping case which contained the raw milk samples. One sample of powdered milk was obtained by removing the powder immediately after drying, while a second sample was removed after it had remained in thedrying chamber for about 2 to 2.5 hours, which the authors understand is the usual procedure in the Perry, E.Y., plant. This was done in order to ascertain whether or not the longer period in the drying chamber exerted a destructive effect on the antiscorbutic properties of the powdered product. The powdered milks used in this study were made a t the Perry, X. Y., plant of the Merrell-Soule Company, under the same conditions as prevail throughout the year. The mixed milk which is used in making the powderedwhole milk is passed through a continuous evaporator or condenser which condenses the milk in a vacuum at a relativelyrapid rate. Unlike the vamum pan method, which is used by many plants, the milk is not in contact with copper, for the interior surfaces are composed entirely of steel. The evaporated milk, which is devoid of dissolved air, passes from the vacuum evaporator through a glass-lined pipe into a closed glass-lined tank which does not allow air to come in contact with the milk. The evaporated milk is pasteurized in this tank a t 145” F. for 30 minutes. The hot evaporated milk is then forced into the heated chamber under an exceedingly high pressure. This is the first time in the entire process that the milk has had opportunity to come in contact with air. The drying is instantaneous, the atomized milk solids falling to the floor of the chamber in a very !he powder. The moisture content of this powder never exceeded 2 per cent. The writers desire to make it clear that their findings apply only to the milk powders under discussion and they do not feel that these conclusions can be applied to sprayed milks in general, the details of production and manufacture of which they have no knowledge. PRELIMINARY WORK The guinea pigs were procured from a number of breeders and shipped to Ithaca in groups of twenty-five to eighty in single crates or shipping boxes, which afforded excellent opportunity for the spread of contagious diseases. As soon as the animals arrived a t the laboratory they were placed in a large cage and given access to oats, alfalfa hay, greens, and milk. The best animals were isolated in individual cages and placed on the basal ration with greens and milk for about 3 weeks. During this period the animals were weighed regularly. Those animals that were not growing normally were removed and the remaining animals were placed on experiment when they weighed about 300 grams. The basal ration consisted (in parts per 100) of ground oats 60, wheat bran 15, autoclaved alfalfa (ground) 15, casein 5, calcium carbonate 1, sodium chloride 1, and butter fat 3. Fresh butter fat was added daily to prevent rancidity. The milk was fed early in the morning, the water having been removed from the cages the night before. I n this way it was not difficult to obtain complete consumption of milk. The powdered milks were mixed with water and stirred with an clgg beater to insure complete solution and suspension of solids, and water was added until the remade milks reached the same specific gravity as that of the raw milks from which they were made. As already noted, Dutcher’s experience has led to the be-
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lief that 30 cc. of cow’s milk usually represents the minimum amount that will protect a guinea pig from scurvy for short periods (90 to 120 days). For this reason it was decided that the raw and remade milks should be fed a t the following levels-20, 30, 40, 50, and 60 cc. I n this way comparable results are possible regardless of the level a t which protection against scurvy may be obtained. Owing to lack of facilities the preparation of histological sections of tissues was abandoned. Inasmuch as only comparative results were desired, clinical symptoms, body weight, food intake, and post mortem examinations were depended upon to give the desired information regarding the differences between the various groups receiving the experimental milks.
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CHART1
EXPERIMENTAL EARLY WoRK-In February, 1922, the experiment was started using eight to ten pigs in each experimental group. I n addition to control groups, there were two general experimental groups each containing sixty animals. These groups received, in addition to the basal ration, (1) raw milk and ( 2 ) powdered milk. The total number of animals used in the early preliminary work numbered about two hundred, and one hundred and fifty animals were added later as the experimental work progressed. An epidemic of influenza and pneumonia ran through the entire colony before the experiment had progressed many weeks, with the result that a large number of animals died and others were so ill that it was impossible to obtain satisfactory data. The same was true for the new groups that were placed on experiment in the spring and summer. In spite of the inconsistent data obtained in the first half-year’s work, it was evident that there was little difference between the experimental groups receiving the same quantity of the various experimental milks. I n other words, no difference could be distinguished between the milk powder removed immediately after drying and that which remained in the drying chamber from 2 to 2.5 hours. Of the animals that remained free from disease, those receiving summer milk grew much better and developed scurvy less readily than those receiving the same quantity of winter milk. I n repeating the work it was planned to dispose of the entire stock of animals and obtain new stock from other breeders. All cages and utensils were sterilized throughout the entire experiment by means of a large sterilizer constructed for the purpose. There was no doubt but that the source of stock and the shipping of large numbers of animals in a single crate were responsible for the trouble.
INDUSTRIAL A N D ENGINEERING CHEMISTRY
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SECOND SERIES O F EXPERIMENTS-In order to avoid further trouble, a man was sent (duringoctober, 1922) to a prominent breeder of guinea pigs with instructions to pick only healthy animals weighing about 210 to 280 grams. These were chosen very carefully and placed in a specially constructed carrying case containing eighty compartments, each large enough for one animal, thus preventing, as far as possible, chance for the spread of contagious diseases. This case was transported to and from the train in taxicabs and the animals were received a t the laboratory in the best of physical condition. The usual prefeeding period was restored too and only one animal was removed from the entire group because of failure to grow. This method eliminated further trouble and all animals obtained in this way were highly satisfactory. 450
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fruit juices from the beginning. The powdered fruit juices weremade by thespray process in a manner similar to that used in making powdered milk. The growth of the animals and the absence of scurvy seem to show that the basal ration was satisfactory in all particulars with the exception of vitamin C. Incidentally, these experiments indicate that the powdered fruit juices have retained their antiscorbutic potency. Chart 2 summarizes the results obtained in feeding seventy animals on milk. The curves are self-explanatory. The raw milk and powdered milk groups are very readily compared. As indicated in the preliminary paper,13 scurvy developed in practically the same time in all groups except those receiving 40 cc. of raw and powdered milk. I n the last-mentioned groups autopsy revealed one mild case of scurvy in the powdered milk group and four mild cases in the raw milk group. These results possess no significance other than to indicate that there was no difference between the nutritive properties of the raw and powdered milks so far as these differences can be measured by the methods employed. DISCUSSION
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CHART2
Hume’s work12 on condensed milk indicated that vacuum condensation does not possess a destructive effect on vitamin C. On this account, feeding tests with evaporated milks were omitted. The quantity of milk fed to the various groups was limited to 20, 30, and 40 cc., because it was felt that the best results for comparative purposes could be obtained a t these levels, inasmuch as some of the animals receiving 30 cc. of summer milk in Series 1 made fairly satisfactory growth and did not develop scurvy symptoms for periods of 120 days and longer. The experiment proper was started in the last week of October, 1922, and terminated in January, 1923. No difficulty mas experienced in making the animals consume the required amount of milk. Although records were kept of the food intakes of all animals, no striking facts were obtained; hence these data are not included. The data have been averaged for each group and the growth curves of the animals in the second series are given in Chart 2. Chart 1 is included to show that the basal ration was deficient in vitamin C but seemed to be very satisfactory otherwise. The first curve is the.average for eleven animals. All animals developed decided scurvy symptoms but failed to lose in weight as rapidly as guinea pigs usually do on oats alone. Appetites were also somewhat better during this period, indicating that the basal ration was more satisfactory than some that have been used. At J some animals received from 2 to 3 cc. of fresh lemon or fresh orange juice or equivalent amounts of powdered lemon or powdered orange juice. The response in growth and appetite accompanied by the disappearance of scurvy symptoms indicates the satisfactory nature of the basal ration. The remaining curves in Chart 1 represent twenty-nine animals that received fresh or powdered
This is the first work, so far as the writers are aware, in which commercially prepared powdered milks have been compared with the raw milk from which the powders were made. It is quite evident from the results that the spray process of itself is not the destructive agent in the milk studied by other investigators, for this is one part in the manufacturing process that all sprayed milk plants possess in common. The writers are frank to admit that the results came as a surprise for they could not help but feel, at the beginning of the experiment, that the existing information tended to indicate that oxidation in the drying chamber would bring about vitamin destruction to a very marked degree. Since this does not seem to be the case, they are inclined to the belief that the drying process was so rapid and complete that there was little or no destruction of vitamin C. Slow drying a t moderate temDeratures in the Dresence of oxygen is known to be destructive’to this vitamin.& It is concei;lble that the oxidation may take place readily in the presence of moisture while it is probably eliminated in the absence of moisture. Sherman and Grose14have voiced a similar suggestion with reference to the thermo-stability of vitamin B. This vitamin was more readily destroyed in the presence of water (liquid milk) than in the absence of water (powdered milk). Inasmuch as other chemical reactions (in solution) are increased with rises in temperature, there is every reason to believe that oxidation of vitamin C, and possibly other vitamins, will be assisted by the presence of moisture and depressed by the absence of moisture. The writers are also of the opinion that the preliminary treatment of the milk must be considered. Hess15has shown that small amounts of copper act as a catalyst aiding in the destruction of vitamin C by heat. A prominent authority on condensed milk asserts that considerable copper is dissolved in evaporated milks made by the vacuum pan method which requires continuous contact of hot milk with copper for 2 to 4 hours. Rice and Miscall16 have published very interesting data on this point. The writers have already pointed out that the milk used in this investigation was evaporated in a continuous steel vacuum evaporator through which the milk passed in a few minutes. This difference in manufacturing methods may help to explain the results. Furthermore, the closed system of pasteurization in the absence of air is another precautionary measure not resorted to in many plants. CONCLUSIONS Freshly prepared whole milk powder-made by condensation in a steel continuous evaporator and pasteurized, after
October, 1924
INDUSTRIAL A N D ENGINEERING CHEMISTRY
condensation, in a closed glass-lined tank, in the absence of air, and sprayed under pressure into a heated chamber, as practiced a t the Perry, hT.Y., plant of the Merrell-Soule Company-possessed antiscorbutic properties identical with the raw milk from which the powder was made. I n other words, the experimental evidence indicates that there is no destruction of vitamin C by this process, so far as vitamin destruction can be measured by the guinea pig feeding methods described. REFEREKCES I-Rarnes and Hume, Lancet, 1919, 11,323. 2-€Cart, Steenbock, and Ellis, J B i d . Cham., 42, 383 (1920).
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a-Dutcher, Eckles, Dahle, Mead, and Schaefer, I b i d . , 45, 119 (1920). 4-Hess, Unger, and Supplee, I b i d . , 45, 229 (1920). 5-Kennedy and Dutcher, Ibid., 50, 339 (1922). 6--Hughes, private communication. 7-Hess and Unger, A m . J . Diseases C h i l d y e n , 17, 221 (1919). 8-Anderson, Dutcher, Eckles, and Wilbur, Science, 55, 446 (1921). 9-Hart, Steenbock, and Ellis, J . Biol. Chem., 46, 309 (1921). 10-Johnson and Hooper, U . S. P h i c Health Service, Pub. Health Refits., 743 (1922). 11-Jephcott and Bachararh, Aiochem. J., 15, 129 (1921). 12--FIume, I b i d . , 15, 163 (1921). 13-Cavanaugh, Dutcher, and Hall, A m . J . Diseases Childverr, 25, 496 (1923). 14-Sherman and Grose, J . A m . Chem. S o c . , 45,2728 (1923). 1.5-Hess and Unger, Proc. SOC.Ezfitl. B i d . M e d . , 19, 119 (1921). 16---Rice and Misca!!, J . Daivy S c i . , 6, 261 (1923).
Organic Refrigerating Brines’ By Harper F. Zoller N I Z E RLABORATORIES Co., DETROIT, MICH.
HE purpose of this paper is to arouse interest in certain new applications of old data and to show that a careful adherence to chemical theory, particularly those theories which have been judiciously studied, cannot lead one far astray. Those laws of physical fact discovered and studied by Raoult, Xernst, Jones, Loomis, Abegg, Morse, and hosts of others still hold true today. A molal aqueous solution of glucose still continues to lower the freezing point of the solution by a constant amount. Amyl alcohol possesses no newer properties in this motor age than it did in the days when it was subjected to critical study; although strange and wondrous qualities have been recently associated with it which enabled it to hold water i n the liquid state a t exceedingly low temperatures. In past industrial practices inorganic aqueous brines have been used entirely. Calcium chloride has been most used partly because a t equal concentrations it will permit of lower temperatures without freezing than will be obtained with sodium chloride and partly because it is more soluble in water. Inorganic brines are extremely corrosive in their action on metals. Their wear and tear on machinery is considerably an economic loss. The development of small refrigeration units for the home and retail store has introduced an entirely new problem. I n the large refrigeration plants iron is the main metal in contact with the brine, although brass is quite often used for certain connections. With the small automatic units the chief metal in contact with the brine is copper or tin, and in these frequently are soldered (tin and lead) joints. Calcium chloride is very corrosive on soldered joints. Electrolytic action is rapid, as is likewise oxidation. Consequently in this laboratory the available brine substances with lower dissociation constants which would glve the proper fluidity] freezing point lowering, and freedom from exressive corrosion, have been sought. After a careful review of prices, which are largely controlled by the availability of the material, and the results of several months of experimentation, specially denatured industrial alcohol in aqueous solution was finally chosen. Certain special features of denatured alcohol (ethyl alcohol) which makes it the most adaptable of all brines for all types of refrigeration plants will be considered later, after first dealing with more general phases of the problem. Organic refrigerating brines may be divided into two classes -aqueous and nonaqueous. The freezing point of aqueous brines is determined by the size of the molecule of the
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1
Received May 3, 1924.
solute, its dissociation and its solubility in water. With nonaqueous brine the freezing or solidifying point is determined by intramolecular forces in the substances, or, in other words, by its special properties. XONAQUEOUS BRINES I n order that a substance may be considered for an industrial use it must be easily obtained and therefore cheap. In the realm of nonaqueous brine, therefore, we would be forced to turn immediately to the hydrocarbons. I n general, the hydrocarbons are cheaper than the liquid esters, ethers, or chlorine and sulfur derivatives of the same. Among the hydrocarbons, kerosene and benzene are quite plentiful. Very low temperatures may be reached with either one without solidification, but they have odors which are difficult to remove. Moreover, they are inflammable and it is doubtful if they would ever receive the sanction of the Underwriters’ Laboratories for such use. Kerosene has a further bad property-namely, that of creeping over the surface of metalsand would not, therefore, be safe to use around food materials. The ethers and esters (except the true fats) are inflammable, too odoriferous, and too expensive for consideration in this connection. The liquid fats qll solidify at temperatures entirely too high for refrigeration purposes. There is a group of substances such as the chlorine substitution products of the hydrocarbons, of which carbon tetrachloride is an example. Most of these substances are practically noninflammable and therefore eliminate to a large extent the fire hazard. These chlorine derivatives can be admixed with the hydrocarbons, such as kerosene, thereby reducing the fire hazard of the latter, but there are certain objections to the employment of carbon tetrachloride and its near relatives in brine tanks and circulatory systems. Their vapor pressure is usually very high and consequently large losses of the brine result. They all possess objectionable odors which are absorbed by food products rendering their use unsafe from this standpoint. AQUEOUS BRINES Inasmuch as the cheapest diluent is water, attention must be given t o the aqueous organic brines. These have been termed “brines” to connote their use. Although they had not been used for brine production in this country before this laboratory determined upon their value, they have since opened up a wide and fruitful field of investigation for chemical engineers.
