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TABLE 6.-Influence of holding temperature on the occurrence of sandiness.

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Heat shocking-By heat shocking is meant the practice of permitting the frozen ice cream to become slightly softened by exposure to warmer air, and immediately frozen again. This was practiced on the experimental mix for 3 days. Sandiness occurred in that sample in the hardening room in 6 days, while a sample of the same mix not treated did not show sand in hardening until the nineteenth day; one under cabinet conditions did so in 8 days. All mixes subjected to heat shocking produced similar results. All lots kept in cabinets were shocked more or less, since the ice cream was usually somewhat soft when repacked. All cabinets were repacked in the morning and late in the afternoon. The long period from 5 p. m. until morning usually caused the ice cream to become slightly soft. The ice capacity of the cabinets was not large enough to insure absolute firmness of the ice cream all of the time.

DISCUSSION AND CONCLUSIONS.

It will be noted that in the first experiment where sugars were used as inhibiting factors there was no pronounced effect. It has been stated by practical investigators that high sugar content caused the precipitation of lactose to become less and in some instances prevented it entirely. This view was not borne out in these experiments. The additional sugar in the mix from sources such as sucrose, glucose, and sirup increase the total solid content of the mix and at the same time decrease the available water for holding the lactose in solution, and competes for the water of the mix. The more sugars and other solids added, then, while the per cent of lactose on the basis of the mix remains constant, the higher will be the concentration of lactose in the water of the mix.

Colloids have but little if any commercial value in protecting against lactose precipitation. This conclusion bears out the work of other investigators previously mentioned. The amount of gelatin necessary to delay somewhat the occurrence of sand is too great to be of any practical use.

It was also noted that rennet offered no inhibiting influence on lactose crystallization. Rennet acts on the casein of milk and causes a coagulation or gelation under normal conditions. It is doubtful if this could happen at the low temperatures to which these mixes were subjected. In the coagulation of casein we have syneresis, which may tend to encourage the precipitation of lactose rather than to inhibit it.

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PROCEEDINGS OF THE WORLD'S DAIRY CONGRESS.

The degree of concentration of lactose in aqueous solution is by far the greatest single factor in the formation of sand. It is possible to have a lactose content on the basis of the mix which may give sand in one case and not in another. This depends on the per cent of total solids, or on the other hand the per cent of water in the mix. More lactose can be supplied from condensed milk or milk powder in a low-solid mix than in a high-solid mix without danger from sand. A mix containing 10.8 per cent of serum solids, with 14 per cent fat and 15 per cent sugar, will be in danger of becoming sandy in time. A mix containing the same amount of serum solids, with 8 per cent fat and 12 per cent sugar, will not be in such danger of becoming sandy. A mix containing as low as 8.7 per cent lactose based on the water of the mix became sandy under conditions which favored sand occurrence, such as temperature changes or heat shocking. While it was possible to produce sandy ice cream in ice cream having as low as 8.5 per cent lactose in the water of the mix, this amount could not be considered as dangerous, since the time required to produce this sandiness in these instances was much longer than the time the manufacturer usually holds ice cream.

High temperature ranks next to lactose concentration in importance as a factor inducing sandiness. Whenever the ice cream was packed in cabinets where the temperature could range between 5° and 20° F. there was found a more rapid formation of sand. A temperature of -10° F. to 10° F. in the hardening room prevented the crystals from forming so soon. This has been explained as being due to the faster rate of diffusion in soft ice cream. The rate of diffusion of tactose is very much slower when a lower temperature is maintained. A constant low temperature (0° F.) gave better results than temperatures which fluctuated between – 10° F. and 10° F.

REFERENCES.

1. HUNZIKER, O. F. Condensed milk and powdered milk, ed. 3, LaGrange, III.

1920. 2. BOTHELL, F. H. Proc, 5th Ann. Convention, Pacific Ice Cream Manufactur

ing Assoc., Portland, Oreg. pp. 121–125. 1920. 3. ZOLLER, H. F., and WILLIAMS, O. E. Sandy crystals in ice cream, their sepa

ration and identification. Jour. of Agr. Res., v. 21, pp. 791-796. 1921. 4. PURDUE UNIVERSITY AGR. Exp. STA., 33d Ann. Rep., Lafayette, Ind. 1920. 5. Evans, R. D. Thesis for master's degree in agricultural biochemistry, Uni

versity of Minnesota. (Unpublished.) 1922. 6. WILLIAMS, 0. E. Sandy ice cream. New York Prod. Rev., v. 53, pp. 878-884.

Mar. 1, 1922. 7. DAHLE, C. D. Watch for sand. Ice Cream Rev., v. 6, pp. 22–24. 1923. 8. HUDSON, S. C. Sugar crystals (further studies on the forms of milk sugar).

Jour. Amer. Chem. Soc., v. 30, pp. 1767–1783. 1908. 9. MOJONNIER, TIMOTHY, and TROY, Hugh C. The technical control of dairy

products, ed. 1. Mojonnier Bros. Co., Chicago, Ill. 1922.

SESSION 11. METHODS OF IMPROVING AND PROTECTING

THE MILK SUPPLY.

Honorary chairman, NicoLAS CHAVARRIA MORA, engineer, San Jose, Costa Rica. Chairman, IVAN C. Weld, secretary-treasurer, International Association of

Dairy and Milk Inspectors, Washington, D. C. Secretary, Dr. C. L. ROADHOUSE, professor of dairy industry, University of Cali fornia.

FIRST BAPTIST CHURCH ASSEMBLY HALL, Syracuse, N. Y., Saturday, October 6, 1923—9.30 a. m. Chairman WELD. We have come together this morning to discuss some of the important phases in the control of qualities and in the protection of the milk supply of the people. We have about seven foreign countries represented here as well as our own. I hope that information will be developed during the morning which can be carried by you to your respective States and countries, and which will serve the most useful purposes in the protection of your people.

I take great pleasure this morning in being able to introduce to you our honorary chairman, Nicolas Chavarria Mora, former Director General of Public Works, Costa Rica. [Applause.]

Honorary Chairman CHAVARRIA MORA. Ladies and gentlemen: I wish to express my cordial thanks to the executive committee of the World's Dairy Congress for the honor they have bestowed upon me in designating me honorary chairman for the eleventh session, and it is in this capacity that I have the honor of addressing to you a few words in my broken English, which I beg you to excuse.

As you well understand, I am not going to speak about the "Methods of improving and protecting the milk supply,” which is the subject of this session. Prominent technical men, as stated in the program, will discuss this interesting subject, which is of real and actual value to our Latin American countries, where, with very few exceptions, the dairy industry is still in its infancy. That is just the reason for our coming to your country, taking advantage of the kind invitation extended by the Government of the United States of America to our own governments to attend the sessions of the World's Dairy Congress, whose work is of capital importance, not only for North America but for every nation in the world.

People of every country come to the United States to learn how to make laws and how to respect them, to pay homage to your iorefathers--the fathers of this wonderful Republic, whose place aniong the civilized nations is in the front line; to admire the warm patriotism of all the citizens of the United States of America; and to inquire into your wonderful material progress as represented by your extensive and well-equipped railways, your magnificent highways, your remarkable sanitary works, and your monumental public buildings and memorials.

We come here to learn many things connected with the dairy industry, such as the nutritional value of milk, the methods of educating the public to the use of milk, milk in the diet, city milk problems, the chemistry and bacteriology of milk, the control of the quality of milk. Many other aspects of the subject are of great importance to us as matters of public hygiene, tending to protect the health of people and particularly the lives of children. This is the most Christian duty of rulers of peoples and the best means to increase population. This is one of the most important needs of our young Latin American republics. I thank you. [Applause.

Chairman WELD. I am sure we all respond most cordially to Doctor Chavarria's generous sentiments. We all hope that this session will contribute to the advancement of sanitation and industry in this and other lands.

A question which has confronted many municipalities and has confronted all of us is how we can efficiently control our milk supply. This question will be the subject of a paper presented by Dr. C. J. Hastings, medical officer of health, Toronto, Canada. [Applarise.]

HOW CAN WE BEST SAFEGUARD OUR MILK SUPPLY.

CHARLES J. HASTINGS, M. D., C. M., L. R. C. P. I., LL. D., D. Sc., medical officer

of health, Toronto, Canada.

There are two activities in connection with every department of public health that are prerequisite to anything approaching efficient administration. These are the safeguarding of the water supply, and the safeguarding of the food supply, with special reference to milk. Any community failing in these two activities is guilty of criminal negligence, inasmuch as sins of omission, in public health administration at least, are no less culpable than sins of commission. From 50 to 75 per cent of all infants dying from diarrheal diseases should have their death certificates filled out “poisoned by milk." There is not a necropolis, not a graveyard, in this country, or probably in any other country, that is not dotted over with little gravestones, tombstones, and monuments marking the graves of those whose lives have been sacrificed to impure milk.

The late Sir William Osler, regius professor of Oxford, when visiting the home of his birth several years ago, met an old schoolmate. She was married and her dress gave evidence of recent bereavement. They entered into conversation, recalling their boyhood and girlhood days at the preparatory schools. Sir William asked her if she were married; she replied that she was. “How many children have you?” “I have had seven; five of them have died." Sir William naturally inquired the cause of death, to which she replied “ Cholera infantum, summer complaint," etc. " However," she continued, " I have been quite reconciled that it was the will of Providence to take them away.” After a brief pause, Sir William said, in his usual frank way, calling her by name: "Mary, Providence had nothing to do with it. Your children were poisoned by impure milk.”

The universal ignorance, until recently, of the dangers of impure milk has been pitiful. One occasionally sees evidence of this ignorance in the actions of presiding magistrates or judges in our different courts. Recently a presiding magistrate in this country, after evidence had been given as to carelessness in connection with the production of milk, and the prosecution of a certain vendor for having offered for sale impure milk containing barnyard contamination, said: “Oh, yes; I hear much about this impure milk. It seems to me that the cow would have to have a bath every time before milking in order to have clean milk," and there was no conviction. Such expressions of opinion, such expositions of ignorance, promptly place such presiding magistrates or judges in the class of those who occasionally rush in where angels fear to tread. A decision of such character from a magistrate in my city would call forth such ridicule from our department that the bench would decide to think in the future before handing down judgment. I have a profound respect for the bench, but only in so far as the presiding magistrate or judge merits it. The bench is not always omniscient.

Probably no other phase of preventive medicine has engaged the attention of public health administrators, for the past 10 years at least, to a greater extent than has the efficient safeguarding of the public milk supply; advisedly so, for in a modified form, it is the only efficient or reasonably efficient substitute we have for mother's milk. There is no other food comparable in value for invalids; in fact it should enter largely into the diet of all. Milk in some form, and its products, butter, cream, cheese, ice cream, are among the most important articles used for human food and constitute a large percentage of the food used by civilized man.

Education, legislation, cooperation, and administration would seem to constitute the chief cornerstones upon which to construct a permanently efficient milk control. In our educational campaigns we must endeavor to enlighten our citizens, first, in regard to the food value of milk; and, second, in regard to the dangers lurking in ordinary market milk; the enormous possibilities of contamination; the character of these contaminations, and the best ways and means of safeguarding the milk. Nine-tenths, if not nineteentwentieths, of the permanent efficiency of all public health administration is obtained through education. The same is obviously true of our milk control, which necessarily constitutes one of the most essential parts of public health administration in any community. It must be apparent that we can not hope to have efficient legislation without arousing public sentiment to the necessity for it. Consequently we must demonstrate to our citizens that milk is the most valuable article of food we possess, that modified cow's milk is the most efficient substitute we have for mother's milk, inasmuch as it is in itself a perfectly balanced diet. However, it is well to note that whether or not milk contains all three of the necessary vitamins or accessory food factors, depends on the food of the herd. In order to secure this perfect food, properly balanced, the fodder for the herd must always contain these vitamins.

In addition to this, we must also demonstrate that milk constitutes the most efficient food we have for invalids, and that, in fact, the developing boy and girl should consume at least a quart of milk every day, in order to supply that which is essential for perfect physical development, and every adult should consume daily at least a pint of milk, to maintain those essentials. And, furthermore, we must demonstrate that milk is the most economical food we have, that with the addition of bread or cereal it constitutes a perfectly balanced

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