( Originally Published 1939 )
Milk and a wide variety of animal and vegetable fats and oils are used for the manufacture of margarine. Different manufacturers select those fats which they can use to best advantage. The determining factors may be their price, their quality, or their physical properties. Those most generally used are oleo stock, oleo stearin, neutral lard, soybean oil, peanut oil, coconut oil, cottonseed oil, palm oil, and various hydrogenated oils. All these oleaginous materials must be very highly refined and deodorized so that they do not impart any off-flavor to the margarine.
Milk is almost always used in making margarine, although in foreign countries milk whey has been used to some extent. Usually skim milk of excellent quality is pasteurized, cooled, and then is cultured with strains of bacteria similar to those used in the culturing of cream for butter making. When the proper acidity desired by the individual manufacturer has been reached, the milk is measured and pumped into a double-jacketed tank equipped with agitators. Here it is heated and violently agitated.
In the meantime, a blend of the desired oleaginous materials has been weighed or measured. This blend is chosen of products that will impart to the finished margarine a melting point similar to that of butter. For example, stearin is a solid fat at room temperature, coconut oil is a soft fat either solid or liquid according to relatively slight changes in temperature, and cottonseed or soybean oils are liquid. The melting point (or titre, as it is called) may be made to vary according to the proportions of these ingredients.
While the stirrer is working at full speed in the tank of milk, the warm oil mixture is allowed to flow in. A cover prevents the mixture from splashing out of the tank. The amount of oleaginous material is about four times that of the milk. A thermometer on the tank and the glass peephole enable the operator to control this mixing operation.
Sometimes a lecithin compound is added to facilitate the formation of an emulsion. This may be in the form of egg yolk or soybean extract. Glucose may be added to darken the margarine and facilitate the formation of foam when it is heated for cooking purposes.'
When the mixing is complete, the batch is allowed to cool slowly. It gradually loses its clearness and begins to adhere to the glass. The temperature, which has been falling, now starts to rise, indicating that the fat is beginning to solidify. A valve in the bottom of this tank is then opened, and the emulsion, looking like a thin custard, is discharged against a sheet of a powerful, ice-cold water spray. The mixture of water and congealed emulsion is dropped into a long wooden tank. The margarine in the form of small lumps floats on the surface of the water. This operation washes the milk out of the emulsion. Workmen with scoops skim off the margarine and place it on tables for working. In some plants the emulsion is chilled on refrigerated rolls somewhat as lard is handled, so that the milk is not washed out but is conserved. The purpose of the sudden chilling is to congeal the mixture and preserve the emulsion. Margarine differs physically from butter in that butter is an emulsion of water in oil, whereas margarine is an emulsion of oil in water.
The margarine is then worked or kneaded between fluted rolls to squeeze out the excess water, to impart proper texture, and to facilitate the mixing of the salt. Some operators allow it to stand in a con-trolled temperature room to improve its texture and flavor.
The margarine is next packed into prints, and wrapped by regular butter-handling machinery. It may be kept in cold storage for weeks or even months. Wrapping in clean parchment and protection from high temperature, light, and mold organisms increase its keeping qualities.
Only about 5 percent of the margarine is colored because of the high tax. Manufacturers supply the color in a small capsule with each carton of margarine so that the consumer himself can work the color into the product.
RELATION TO THE PUBLIC HEALTH
Composition and standards. Margarine is made of a mixture of fats and oils, emulsified with cultured milk, and salted to taste. Oleomargarine contains animal fats, and may or may not contain vegetable fats. Nut margarine contains no animal fats, but only vegetable fats. Table XVIII shows typical analyses of these two kinds of margarine.
Sometimes a preservative is added, although margarine will keep as well as butter under equal conditions of care. The glycerin derivative may contain a hydrophilic grouping, such as a sodium salt of a hydroxy-fatty acid compound, added to prevent spattering of the margarine when heated.
Although oleomargarine and nut margarine have grown to have somewhat different significance, the federal statute which defines these products, as well as some others in this general category, calls all of them oleomargarines. It provides that all substances shall be known as oleomargarine which consist of oils or fats made to resemble butter or intended to be sold as butter or churned or mixed with milk products and salted.' A tax of 1/4 cent per pound is levied on each pound of oleomargarine that is manufactured, but this is increased to 10 cents if the oleomargarine is yellow in color. In addition, there are other special taxes to each manufacturer, wholesaler, and retailer.
The Commissioner of Internal Revenue of the U. S. Treasury Department has charge of the enforcement of the federal statutes which relate to the licensing and taxing of companies engaged in the production and handling of oleomargarine, and adulterated, process, and renovated butter. He publishes regulations which define his enforcement procedure, and a weekly bulletin of information on the ingredients and current production of oleomargarine. All these products which contain any ingredient injurious to the public health may be seized by the Collector of Internal Revenue for examination by the 'Commissioner and destroyed. An appeal board consists of the Surgeon General of the Army, the Surgeon General of the Navy, and the Secretary of Agriculture.
Regulatory problems. The author has not found any recorded case where margarine has been the agent in an outbreak of communicable disease. The most important problems which it presents to the food-control officer are its use in the public diet and the tendency for unscrupulous dealers to market it fraudulently in place of butter.
The calorific, protein, and mineral values of margarine and butter are substantially the same. However, their vitamin values are very different. Butter contains an abundance of vitamin A 5 and a little vitamin D. Most nut margarines contain much less. Oleomargarines contain appreciable amounts of both. Margarines contain about 2 or 3 times as much milk solids as butter, and therefore more of the water-soluble vitamins B and G (riboflavin).
If the public consciously or otherwise has been depending to a substantial degree upon the vitamin A content of butter, and changes to margarine, then vitamin A must be provided from some other source; otherwise, serious avitaminosis (a diseased condition caused by lack of a vitamin) will result. This occurred on a large scale in Denmark during the World War when the thrifty Danes sold all the dairy products that they possibly could at high prices and imported cheaper margarine for their own consumption. In this country, how-ever, it has not been definitely proven that there is any such problem from margarine consumption, although avitaminosis A has been re-ported among persons in the lower economic levels. Some margarine manufacturers are now fortifying their products with vitamin A.'
The food value of margarine consists almost entirely of its fat. This is fully as digestible as that of butter, and just as nutritious. When part of a well-balanced diet, margarine is a good food supplying as many calories as butter.
1. K. SNODGRASS, Margarine as a Butter Substitute, Food Research Institute, Stanford University, California, 1930; W. CLAYTON, Margarine, Longmans, Green and Co., London, 1920.
2. J. Am. Med. Assoc., 106, 1809 (1936).
3. Ibid., 105, 369 (1935).
4. Bureau Internal Revenue Regulations 9, U. S. Treasury Dept., 1936.
5. C. F. PoE and H. A. FEHLMANN, J. Dairy Sci., 16, 559 (1933).
6. P. C. JEANS and Z. ZENTMIRE, J. Am. Med. Assoc., 106, 996 (1936); H. JEGHERS, Ann. Internal Med., 10, 1304 (1937).
7. U. TANCE, Bull. Inst. Phys. Chem. Research, Tokyo, 14, 125 (1935), from Chem. Abs., 29, 6929 (1935).
8. J. S. ABBOTT, Institute Margarine Mfrs. Bul. 10, 1930.