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(4) State agricultural colleges. (5) State agricultural experiment stations.

The ice-cream industry has been developed by men who have employed sound business principles; they have occasionally received help from outside sources. The ice-cream cone, 1904, aided in increasing the sale of ice cream, as did also the Eskimo pie.

The greatest advance in ice-cream machinery was made in 1902–3 with the introduction of the horizontal brine freezer. This was followed by the introduction of the homogenizer and other machinery at present found in an up-to-date ice-cream factory.

The Ice Cream Trade Journal, the first trade paper in the icecream field, was started in 1905, and was followed in 1916 by the Ice Cream Review. The first college textbook giving instruction in the manufacture of ice cream was Dairy Technology, by C. Larson and Wm. White, 1913. The first textbook dealing exclusively with the manufacture of ice cream was written by J. H. Frandsen and E. A. Markham, 1915. This was followed in 1919 by The Book of Ice Cream, by W. W. Fisk.

The Pennsylvania State College offered instruction in ice-cream making as early as 1892. At present instruction in ice-cream making is offered by 30 State agricultural colleges that give fairly thorough and scientific instruction to from 600 to 700 students annually.

Niręteen State agricultural experiment stations and the Dairy Division in Washington, D. C., carry on experimental or research work on problems related to the ice-cream industry. The first bulletin on the subject of ice-cream making was published by the Vermont Agricultural Experiment Station in 1910. At present 22 experiment station publications are available on the subject.

The problems that have been investigated up to the present time are mainly those related to flavor, texture, and bacteriology. It has been definitely determined that there is a relation between the composition of ice cream and the flavor and texture. Several defects in ice cream have been studied and remedies suggested. The relationship of viscosity to texture has been studied to some extent. Many bacterial analyses of ice cream have been made and methods of reducing the number of bacteria suggested.

Chairman MARTIN. I think you will all agree Mr. Mortensen has delivered us a very valuable paper.

Our next paper is one by Mr. William White, dairy manufacturing specialist, United States Department of Agriculture, on “ The preparation of standardized mix in country plants.


WILLIAM WHITE, dairy manufacturing specialist, Dairy Division, United States

Department of Agriculture.

In some parts of this country there are creameries receiving large quantities of milk that are equipped to manufacture several or all of the standard dairy products, such as sweet cream, butter, plain or sweetened condensed milk, skim milk powder, American cheese, cottage cheese, and casein.

At these plants the milk is turned into the products that are most profitable at the time or those which the market conditions require. In recent years some plants have included in their list one additional product, and that is standardized ice-cream mix. This has become a commercial product only in the past few years since we came to realize the importance of having mix exactly standardized in composition.

The product is so new that practically no statistics have been compiled to show how much is made. New York State has production figures on mix for the past two years, and Wisconsin plans to include the item this year. Standardized ice-cream mix has found a demand in certain trades, and its use is increasing as it becomes better known.

One of the problems of the ice-cream manufacturer is to have a supply of raw material adequate in quantity and satisfactory in quality. Because the demand for ice cream varies greatly from season to season and even from day to day, the milk and cream requirements of the ice-cream manufacturer vary greatly. The production of milk and cream and therefore the available supply bears little relation to the needs of the ice-cream trade. For example, icecream production in July may be two and one-half times as much as in April, while milk production in July may be only one and onefifth as much as in April. If the ice-cream manufacturer can arrange to procure raw material in just the quantity he requires at all times without paying too dearly for the service the situation is ideal.

The large manufacturer frequently finds it desirable to purchase milk and cream direct from the producer, often having country plants for this purpose. During a part of the year, he has a surplus to be sold or manufactured into other products; another season he may find it necessary to supplement his regular supply by purchases from plants that may be in a position to serve him. His raw materials usually are shipped from his own country plant or from other creameries and condenseries, as needed, to his city plant where the mix is made and frozen.

Several large companies that have more than one manufacturing plant have adopted the practice of making all their mix at one plant and shipping it to the other plants to be frozen. The advantage of this is they are able to reduce their technical force somewhat and they obtain a greater uniformity of product at their different plants.

The small manufacturer who buys his raw material direct from the farmer frequently has difficulty in procuring an additional supply when needed and also difficulty in disposing of a surplus of milk or cream without financial sacrifice.

The demand for standardized ice-cream mix is, to a large extent, from the smaller ice-cream manufacturers or retailers who make their own product. The possible outlet even among small manufacturers is very large because, although there are many plants making more than 500,000 gallons of ice cream a year, there are several times as many that make less than 50,000 gallons.

In the State of Michigan, according to the annual report of the State bureau of dairying for the fiscal year ending June 30, 1923, the plants that make 50,000 gallons or less a year are 85.1 per cent of the total number of plants in the State. In this connection, however, it is well to note that this large number of plants make only 18.36 per cent of the total quantity of ice cream made in the State.

The purchasing of standardized ice-cream mix appeals to the small manufacturer; first, because it solves his problem of a supply of raw material; second, because it relieves him of the labor and difficulty of making his own mix, as proper facilities are often lacking for this purpose; and, third, because it enables him to have a homogenized mix of uniform quality. Many small manufacturers, either through lack of knowledge or lack of equipment, are unable to prepare a standardized mix, their greatest difficulty being in standardizing the percentage of solids not fat. In purchasing a standardized mix the manufacturer obtains not merely a mixture of cream, milk, and sugar, but also the services of the technically trained man who prepared the mix and the services of the high-priced equipment used in its preparation. He receives a. mix that, when properly frozen, has the same body and texture as the product of his large competitor.

Too often the small manufacturer makes his mix by guess, and the percentage of fat and solids not fat varies several per cent from one day to another. He does not have a homogenizer or viscolizer because the first cost looks too big. As a consequence, the texture of his product may be far from ideal.

There are some objections offered by the ice-cream manufacturers to using mix made by another company. One is that the mix may not always be the same, that is, there is a lack of confidence in the firm; and it is unfortunately true that so-called standardized mix has been sold by irresponsible firms, that was of poor quality and therefore caused dissatisfaction. To some extent this has hurt the sale of mis by responsible firms. In the writer's experience, mix of 36 per cent solids was sold to a number of small manufacturers and they reported they could not get much swell, and therefore would not continue to use it. Upon investigation it was found that old-style freezers were being used and the brine supply was inadequate. It was, therefore, necessary for them to have a light mix in order to obtain a satisfactory swell. One manufacturer complained that the mix made a slimy ice cream. He had not been using homogenized or viscolized mix and had been making a coarse-grained product. When he started to use the homogenized mix the contrast in the texture was so great he thought the latter was too smooth. To overcome this he mixed in some unhomogenized mix to produce the texture he desired. So it seems that when selling mix it is a hard matter to please all customers.

The country plant making mix to sell will meet with complaints like these and probably many others. To avoid just complaints it is of course necessary that a good mix be made, and this involves having a thorough knowledge of ice-cream manufacture, and making a product of high quality and absolutely uniform from day to day. One mix may be adopted as the standard that will be satisfactory to the majority of customers, but it may be found necessary to make up special mixes for larger customers who have their own ideas as to what they want. Country plants that are able to make standardized mix without too great an additional expense usually find it a profit


able venture. Frequently, the only additional equipment needed is a homogenizer or viscolizer.

The greatest demand for mix comes at a time when the country plant has a large supply of milk and cream, so a market for mix can be taken care of without interfering with the year-round business they may have for other products. The ice-cream demand does, however, extend well into the season of small production and the plants going into the making of mix must take this into consideration when working up their business.

The relation between the percentage of fat and solids not fat in mix is such that if a certain quantity of whole milk is allotted to mix there will be a surplus of solids not fat to be utilized in some other product, or if the solids not fat are to be utilized wholly in mix, butter or cream may be obtained to maintain the proper balance.

Assuming a mix containing 12 per cent fat and 10 per cent solids not fat, 1,000 pounds of 4 per cent milk would contain enough solids to make 333 pounds of mix and leave 630 pounds of skim milk for other products. This extra skim milk is used to a large extent in making plain or sweetened condensed skim milk; some plants also make cottage cheese or casein.

June butter may be stored and used to supplement the supply of fat later in the summer. For instance, to make 1,000 pounds of mix requires a total of 120 pounds of butterfat; 1,111 pounds of milk supplies all the solids not fat needed and 44.44 pounds of fat. An additional 75.56 pounds of fat is needed and may be supplied by 89.95 pounds of butter containing 84 per cent fat.

Country plants that have engaged in the preparation and marketing of standardized ice-cream mix find in this product a satisfactory outlet for milk solids. Because this is a partly manufactured product and the processing of the material adds greatly to its value, the plant is enabled to obtain a price that nets a very satisfactory profit. Small manufacturers of ice cream and retailers who make their own product find it advantageous to purchase a ready prepared standardized ice-cream mix.

Chairman MARTIN. The next two numbers are papers by W. B. Combs and C. D. Dahle. Is either gentleman present?

MEMBER. May I say for Mr. Combs that he will not be here and unfortunately his paper has not reached me.

Chairman MARTIN. I have his paper right here. I thank you. These papers will be transferred to the end of the list.

The next paper, “ Factors influencing the crystallization of lactose," by Alan Leighton, physical chemist, and P. N. Peter, assistant physical chemist, Dairy Division, United States Department of Agriculture, will be read by Mr. Leighton. Mr. Leighton.


ALAN LEIGHTON and PHILIP NORMAN PETER, research laboratories, Dairy Divi.

sion, United States Department of Agriculture.

From the dairy manufacturer's point of view, lactose is of interest from three angles: First, in its crystallization from whey; second, in its spontaneous crystallization from evaporated and condensed

milks; and, third, in its crystallization from ice cream, creating the so-called sandy ice-cream problem.

The following paper deals with what may be termed pioneering experiments on lactose conducted from a number of different angles to obtain a basis for a well-ordered physical-chemical investigation of “ sandy ice cream” and the separation of lactose from condensed inilks. In this preliminary work a number of interesting facts have appeared which seem to be worth bringing out at this time. Most of the experiments were conducted with aqueous lactose solutions.

Lactose, or milk sugar, is present in milk in a quantity which exceeds that of any other single constituent except the water. It represents to use Van Slyke's figures, 4.9 per cent of the total milk composition, or about 54.4 per cent of the milk solids not fat, or, to express the relationship in another way, there are present in normal milk 5.4 parts of lactose to 100 parts of water.

From a physical-chemical viewpoint lactose is interesting in that it exists in at least three forms, alpha (@) hydrate and anhydride and the beta (R) anhydride. The relationships of these three forms have been investigated by both Hudson (1) and Gillis (2). The normal product crystallized from water solution at ordinary temperatures is the so-called alpha hydrate. This is a hydrate of the alpha anhydrous modification. This anhydrous modification is metastable at all temperatures in the presence of water. When it is brought into contact with water it is almost instantaneously hydrated. At a temperature of about 93° C. there exists a transi-de-hydration point, as it is termed by Gillis, at which with rising temperature the alpha hydrate is completely changed to the anhydrous beta form.

If the hydrated alpha form is dissolved in water, a reaction takes place whereby some of the hydrate is changed to the beta anhydrous form. At any temperature below 93° C. an equilibrium is reached, when there is present in solution about 1 part of the hydrate to 11 parts of the beta anhydrous modification. Thus, as has been clearly pointed out by Hudson, lactose can be said to have an initial as well as a final solubility. The initial solubility is the true solubility of the hydrate, while the final solubility is expressed by the total amount of hydrate plus the equilibrium quantity of the beta form which can exist in solution at a given temperature.

Equilibrium between the two forms in solution is attained but slowly at ordinary temperatures. Its attainment is very greatly accelerated by both hydrogen and hydroxyl ions. The percentages of lactose which are transformed in one hour are found to be:

Per cent.


At 25° C..
At 15° C.

At 0° C
The equilibrium is attained instantaneously at 75° C.

Hudson's values for the initial and final solubilities of the hydrated form of lactose were used in compiling Table 1.

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