historical article from a May 1935
Division of Dairy Industry, University of California
By James H. Boulware
The Dairy Industry of Division of the University of California is located at Davis, California, and is headed by Doctor C.L. Roadhouse. The Division is well equipped for research and instruction in the four major branches of the industry. Chemistry and Bacteriology are taught and studied with regard to their relation to dairy manufacturing in general. A commercial creamery is operated in connection with the Division in order that students may obtain a working knowledge of practical creamery operation. This also gives an opportunity for research problems to be tried out on a commercial scale.
Although courses in dairying were given at the University of California in Berkeley as early as 1880, a Division of Dairy Industry was not organized until 1908 when the Branch of the College of Agriculture was organized at Davis. Major work was offered in dairy industry for the first time in 1918 and the present complete and modern building was dedicated in 1922. At that time the present policy of having each department in charge of a staff member who is responsible for research and teaching in his particular field was initiated.
Instruction in dairy industry is given to degree and non-degree students, in addition to graduate and short course students. The degree student requires four years to complete the course for the degree of bachelor of science. Ample facilities are provided for training in the fundamental sciences and dairy industry. When graduated, the degree student is well trained and is capable of taking a position that should lead in a short time to superintendents or managers positions or to other technical dairy work.
The non-degree course in usually completed in two years. Students in this course receive instructions in dairy manufacturing and in plant operation. They are also given practice courses in the University Farm Creamery. They are well trained for plant or dairy farm positions, however, they cannot be expected to take responsibilities as rapidly as degree students or do advanced technical work.
The California dairy Industry Short Courses are held each year and last for one week. Short course instruction is divided into four groups. These are butter, cheese, ice cream, and market milk. In addition to instruction in these fields, lectures are given which are of general interest to the dairy industry as a whole. The short courses are planned largely for dairy operators and men working in dairy plants or on dairy farms. Regular attendance at the short courses should keep commercial men abreast of modern developments in the dairy industry. The value of the short courses is shown by the large number of men who return each year and by the fact that many graduates of the University frequently return to the short courses in order to keep up with the newer information.
The Dairy Industry Building is a two story structure and is modern in every respect. The second story is used entirely for offices and classrooms, except for the Butter Standardization Laboratory. On the first floor are located the testing, bacteriology, dairy chemistry, and the butter and market milk laboratories. Research laboratories are also located on this floor. The butter and market milk laboratory contains small churns and pasteuizers. By making use of this equipment, students may be taught the fundamentals of butter making and the care of market milk without using the larger commercial equipment which is located in the Creamery.
The Butter Standardization Laboratory is equipped for the analysis and scoring of butter. Here butter from various creameries throughout the State is analyzed and scored weekly. Complete analyses are made and the butter is scored for sediment, body and flavor. This work under the direction of Mr. F.H. Abbott has a result in a marked improvement and a great uniformity in the quality of California butter. Without this work the present high quality of California butter could hardly be maintained.
The University farm Creamery is located in a wing at the rear of the main part of the dairy industry building. This is a small commercial creamery, handling about ten thousand pounds of milk daily. Market milk is processed daily, and butter, ice cream, condensed and powdered skim milk, and several varieties of cheese are manufactured regularly. There are 25 or 30 students each semester who are given practice work in the Creamery Laboratory. Cheddar, Monterey, Brick and Cottage Cheeses are manufactured on a commercial scale, and in addition, other varieties are manufactured in connection with the dairy industry teaching and experimental work.
The market milk department is equipped throughout with stainless steel pipes and fittings to keep the milk from coming in contact with any metals that tend to cause an oxidized flavor. The department is thus enabled to produce consistently a high scoring product. Other departments are fitted with modern equipment and a high quality standard for all products is maintained.
The creamery help consists largely of graduates of the two year non-degree course. Some of the outstanding men of each class are employed for one or two years and at the end of this time they are usually employed by various creameries throughout the state. In this way, students are given valuable practical training which could not be given without the facilities of the Creamery. All students obtain some valuable practice in the Creamery before graduation and the plant and its products are always available for demonstrations or laboratory work.
The present staff of the dairy industry division has been built up largely by additions to the staff of 1918, at which time the present program was started. At the present time the staff consists of twelve members who devoted their entire time teaching, research and extension. The teaching and research staff has been built up with the object of securing a well balance faculty capable of maintaining a high standard of instruction and, secondly, capable of doing fundamental research. The quality of the research work turned out is ample proof that the second of these aims has been fulfilled.
Those of us who have recently taken work at the University here believe that the quality of the instruction received is equal to that of any other institution. Each of the men heading a department is a prominent man is his particular field. Doctor C.L. Roadhouse, who handles the market milk department in addition to his work as head of the Division, is one of the country’s outstanding authorities on market milk. Doctor C.S. Mudge of the Bacteriology Department is recognized as one of the outstanding dairy bacteriologists of the country. Doctor G.A. Richardson of the Chemistry Department had his training under Doctor L.S. Palmer of Minnesota who, without question, is the leading dairy chemist of the country, and Doctor Richardson is one of his prominent graduates. Other outstanding men of the Division are Mr. F.H. Abbott of the Butter Department, Mr. W.C. Cole in ice cream, Mr. C.A. Phillips in cheese, and Mr. D.H. Nelson in the testing of dairy products. This, we believe, comprises one of the well rounded teaching staffs in the country.
Among the outstanding contributions of this Division in research is the work on milk flavors by Doctor C.L. Roadhouse and Mr. J.L. Henderson. These workers have confirmed work showing that feed flavors are not absorbed from the air as was once commonly believed. By feeding cows green alfalfa and other feeds at different intervals before milking, it was found that feeding immediately before milking or during milking caused no bad affects in the flavor of the milk and that feeding one or two hours before milking caused the strongest flavor to be produced. Cows kept from feed for five or more hours, as shown also by other workers, seldom if ever show a feed flavor in the milk. By following feeding practices based on these findings, many of the market milk producers of California are now producing milk with little or no feed flavor.
Other work by these men which, like the work on feed flavors, applies to the entire dairy industry as well as market milk, includes the influence of metals and sunshine on the oxidation of milk fat. This causes the off-flavor in milk which these workers have designated as oxidized. It was known that milk coming in contact with copper became oxidized very easily. The problem of preventing milk from becoming oxidized presented itself. The question as to what metals might be used without danger to the flavor of milk was studied in detail with the result that tin, pure aluminum, and certain chromenickel iron alloys were found to be resistant to the dissolving action of milk, and did not cause the oxidized flavor. As most people use milk and milk products for the reason that they like them, the application of this work and the work on feed flavors with the consequent improvement in milk quality, should result in an increased use of milk and milk products.
The Bacteriological Department under the direction of Doctor C.S. Mudge is constantly striving toward better sanitary methods of milk production and a more complete knowledge of the bacteriology of milk and milk products. Among the contributions of Doctor Mudge and his associate, Mr. F.R. Smith, is the work on chlorine sterilization. At the end of careful study, these men have found that, while chlorine undoubtedly reduces the plate count, its use may still result in high counts in plant practice. This is probably due to the fact that the plate count may not be a true measure of bacterial death, and apparently “dead” bacteria may later cause complications in the way of high counts or spoilage.
Other work by these men include studies of thermophilic bacteria. These bacteria grow best at temperatures around 60 degrees C (140 degrees F) which is the temperature used for pasteurization of market milk. It was found that certain milks held at a high temperature for long periods before cooling and bottling had abnormally large numbers of these bacteria. As these organizisms are very hard to kill by normal sterilization, it is very difficult to rid plants of them. However, further studies showed that contamination by the raw milk supply was very important in this problem. By thorough cleaning and sterilization, both in the plant and on the farm, it had been found that the thermophile problem may be controlled. At the present time, a problem of finding a more suitable media for the growth of streptococcus organisms is being studied. As the bacterial of milk are largely of this type, a solution of this problem would very probably give us a clearer knowledge of the bacteriology of milk.
Some of the important work of the dairy chemistry department had been done in connection with the butter department on “sticky” butter. In the extension work and at the University Farm Creamery, it was noticed that t certain seasons of the year butter made in many sections of the State was almost invariably “sticky.” This problem came to the attention of Doctor G.A. Richardson of the Dairy Chemistry Department and of Mr. F.H. Abbott of the Butter Department and Extension Service. First it was noted that, when the “sticky” butter was produced, the cows were receiving a ration consisting largely of alfalfa hay. That the diet of alfalfa hay was responsible for the defect was confirmed by putting cows at the University Farm on such as diet and making butter directly from cream produced by them. It was likewise found that feeding corn silage with the alfalfa would overcome the defect; however, economic conditions in California are such that the feeding of silage is not feasible in many cases.
A study of the fat from cows on an alfalfa ration showed that the relative proportions of certain fatty acids were changed, thus giving a fat of a different consistency at the normal churning temperature. After considering this, a churning procedure was formulated which would almost entirely eliminate the “sticky” condition. This procedure consists of cooling the cream to a temperature of 10 degrees F and recooled and churned immediately. By using this procedure, the University Farm Creamery and some other creameries in the State have been able to reduce the “sticky” butter produced during the winter season from 10 to 100 per cent of the total output to an insignificant amount.
Another problem that the dairy chemistry department has worked out is a method of detecting gelatin in dairy products. The California State Law prohibits the use of gelatin in dairy products other than ice cream or other frozen products. Under Doctor Richardson’s direction, a method for the detection of gelatin in cultured buttermilk and cottage cheese had been perfected. Another important problem that was studied in connection with the medical college of the University in San Francisco is the use of soft curd milk for infants. In this study, is was found that cows producing curd milk varied considerably in this factor during the lactation period. Soft curd milk was also found to be low in solids-not fat, particularly proteins, and, consequently, low in energy. Due to these factors and the fact that infants did not appear to assimilate this milk any better than normal milks, it was not recommended that soft curd mild be produced on a commercial scale.
Other work of the dairy chemistry department in connection with the Animal Husbandry Division has been on the effect of temperature and humidity on milk production. It was found that varying temperatures changed the yield and composition of milk and the physical and chemical properties of the milk fat. This latter factor is important in that it may affect the quality of some products manufactured from such milk.
The work of Mr. C.A. Phillips of the Cheese Department has been largely a study of methods of improving the types of cheese now made in the State and the introduction of new varieties. The use of pasteurized milk for cheddar cheese manufacture has been studied extensively. Brick cheese had been manufactured and reintroduced in the State through the work of the Cheese Department in connection with the University Farm Creamery. At the present time, Bel Paese cheese is being studied and has been successfully made by Mr. Fred Kopp of the University Farm Creamery.
In the Ice Cream Department, Mr. W.C. Cole and several graduate students have worked largely on methods of improving the texture of ice cream, using the sensory test in connection with microscopic examination as a method of studying texture. At the start of this work an attempt was made to study the effect of different ingredients on ice cream texture; however, it was soon found that freezing methods were of such great importance that they must be studied first.
Ice Cream Texture
Work on the effect of freezing methods on texture has shown that smoother ice creams are produced when the temperature of the freezing medium (brine or ammonia) is low and when the time required to freeze the mix is at a minimum. This work has also been applied to hardening temperatures and it has been shown that faster hardening produces a smoother ice cream. Further work on the effect of various milk constituents on ice cream texture has shown that both milk fat and solids-not-fat are important in the production of a smooth and palatable ice cream.. However, this work is incomplete and has not been published. Other studies by Mr. Cole of a very practical nature, include the effect of fruits, chocolates, and different types of vanilla extracts on the flavor and palatability of ice cream.
Mr. D.H. Nelson of the Butter Department does a large part of the teaching and has charge of all testing work. In this line, he has completed some very valuable work on the reliability of the Babcock Test and modifications of this test.
The work reported has been materially aided by the close cooperation of the members of the Dairy Industry Division. Mr. E.E. Brown, who manages the Creamery Laboratory, has always been helpful in making available to the teachers and research men, the products and equipment of the dairy manufacturing plant.
The Creamery had been organized and equipped for research as well as instructional purposes; however, without the excellent cooperation that exists, much greater efforts would have been necessary to secure the same satisfactory results.
Recent years have seen a marked increase in both the quantity and quality of dairy products in California. Since its foundation in 1908, the Dairy Industry Division has cooperated fully with the industry and has aided this advance by research and teaching. The excellent flavored milk found in many California cities was initiated by work at the University Farm. This information has been spread to a great extent by the annual Short Courses. Other valuable information has been given tot he industry in this manner. Besides contributing new information to the industry, the Division of Dairy Industry has turned out many well trained men, who now hold responsible positions in the dairy industry of California, as well as in some other States.