Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)


Dairy Science


At the South Dakota State University Dairy Science Department, a challenging work is being conducted to develop a new spread type· dairy product which is made almost entirely of dairy ingredients. It contains about 40% fat, 6% protein, 40% water, and 1.9% salts. Among the problems which faced the workers on this project were the process induced changes in the protein and the water holding capacity, which are interlinked. The problem of water holding capacity is increased by the high water content of the product compared with butter, which contains about 16% water. Maintaining the stability of the fat emulsion was another problem which faced the workers on this project. The problem of protein stability and changes of protein properties induced by heat and other processing treatments is of tremendous practical importance in the dairy field. The successful processing of many dairy products is predicated on operations that will avoid destabilization of the milk proteins or, even further, will insure their stability during storage. Protein stability is the resistance of the proteins toward any change in their structure induced by physical or chemical treatments which will result in decreased solubility, changes in molecular size and shape, increased viscosity, and decreased water holding capacity. The natural stability of the colloidal protein system of milk and its products is due mainly to the electrical charges on the particles, which keep them apart by electrostatic repulsion. Hydration also plays a significant role in the natural stability of milk proteins. Stability, water holding capacity, and other physicochemical properties of concern to the dairy processors are highly interrelated and, - often, are mutually affected by processing. In many instances, too, the stability of the fat emulsion is an important factor which determines many properties of the finished product. There is hardly a dairy process or product that does not involve this phase of dairy chemistry. The fat globule is covered with a membrane which includes a mono-molecular layer of phospholipids, principally lecithin. The lecithin molecule has two polar groups; one is soluble in water and the other group is soluble in fat. The lecithin molecules orient themselves at the interface between the fat and the water, keeping the fat globules in emulsion. Thus, lecithin plays a role as natural emulsifying agent. Milk proteins, phosphates, and citrates have a natural emulsifying action, too. The recent trend in the dairy industry is to use a combination of added stabilizers and emulsifiers to maintain a proper stability in many finished products, such as ice cream. The actions of stabilizers and emulsifiers are often closely interlinked. Generally speaking, and it is true for many dairy products, the more emulsifiers are present, the less stabilizers are necessary. The development of stabilizers and emulsifiers to assure more efficient stabilization in dairy products has been a challenging experience to the colloidal and emulsion chemists who have spent much time in this field. All good stabilizers are characterized by their ready dispersibility and solubility. In addition, they provide a desirable body, texture, and maintenance of ·uniformity of finished products. This study was an attempt to solve some of the problems in the area of stabilizers; protein properties, especially water holding capacity; and emulsion stability which were involved in the development of the spread type dairy product. Finally, the writer hopes this study made a small contribution to the wide field of dairy science.

Library of Congress Subject Headings

Dairy products


Includes bibliographical references (pages 70-77)



Number of Pages



South Dakota State University


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Dairy Science Commons