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Overview
Evaporated milk is produced when milk is condensed to half its volume by removing part of the moisture in a vacuum evaporator. However, at this concentration, the milk is still susceptible to microbiological spoilage so the evaporated milk is packaged in cans and heat-sterilized.
Evaporated milk can be stored for practically any length of time at a temperature of 0-15.C. It has a large and diverse market-consumed in tropical countries, at sea and for the armed forces, it is used when fresh milk is not available. It is also used as a substitute for breast milk, for cooking and as coffee cream and is primarily used for recombination in various processed foods such as breads and confectionery.
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Composition
Evaporated milk is whole milk, partly skimmed milk or skimmed milk from which approximately 50 percent of the moisture has been removed. It must contain no less than 25 percent milk solids and 7.5 percent milk fat if whole milk was the raw material. The other two types of milk must be evaporated to contain no less than 17 percent of milk solids other than fat. The evaporated skimmed milk must not contain more than 0.3 percent of fat. Vitamins A, D and C may be added. In order to maintain its viscosity during the storage period, stabilizing salts such as sodium citrate, disodium phosphate or calcium chloride may be added. Sodium ascorbate may be added as a preservative.
Caption text Typical composition for whole evaporated milk Moisture 75.0% Lactose 9.5% Fat 7.5% Proteins 6.5% Ash 1.5% The microbiological quality of the raw material for evaporated milk is basically the same as required in the manufacture of ordinary milk products. There are two other important considerations for its manufacture: the number of spores and heat resistant bacteria in milk and the ability of the milk to tolerate intensive heat treatment without coagulating (protein stability).
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Characteristics
Appearance: Evaporated milk is a sterilized product that is light brown in colour because of chemical reactions between the protein and the lactose (Maillard reaction or browning reaction) occurring during the intensive heat treatment (110-120.C maintained for 15-20 minutes). It possesses the appearance of cream and has a slight cooked flavour.
Storage: Storage temperature and time are two determining factors of the quality of evaporated milk. Commercial evaporated milk stays fresh for up to two years if held at a temperature of 0-16.C but deteriorates rapidly above 21.C. Low temperature storage (0-7.C) also prevents sediment formation caused by the settling out of calcium and magnesium salts. The milk colour becomes brownish and the pH decreases if the storage temperature is too high; discolouration is rapid if the storage temperature is above 32.C. Protein will precipitate if the storage temperature is too low. The body and texture of the product are detrimentally changed if stored at a freezing temperature.Humidity levels of storage areas should bekept below 50 percent to avoid the risk of corrosion of metal cans. Inversion of the cans is a practical way to minimize the separation of fat and other constituents and to prevent the product from forming a surface cream line during extended storage. Swollen or blown cans indicate fermentation and spoilage and should not be used.
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Various uses
For many developing countries, evaporated milk is commonly consumed for its nutritional value. In developed countries, it is often used as an ingredient in various food preparations. Different food industries such as infant food producers, confectioneries, bakeries and dairies use evaporated milk as a concentrated source of milk in many of their finished products. Evaporated whole milk is purchased primarily by the confectionery industry while evaporated skimmed milk is commonly used as a source of milk solids in dairy applications and in the manufacture of ice cream, frozen yogurt and other frozen desserts. It can be heated easily (without precipitation of the proteins) to prepare sauces and to thicken puddings.
Reconstitution is obtained by adding an equal volume of water to evaporated milk.
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Functional properties
Caption text Functional Property Mode of Action Water binding/hydration The water retention capacity of milk proteins and lactose produces better texture in food products and help to maintain their keeping qualities and shelf life. Browning/colour Lactose and proteins react with other sugars during baking or cooking. The Maillard reaction gives a desirable brownish colouration and a caramel flavouring to all kinds of confectionery and desserts. Emulsification Milk proteins act at the oil / water interfaces to form and stabilize fat emulsions. This functional property is required for salad dressings, dairy desserts, soups, sauces and baked products. Whipping/foaming Milk proteins act at the air / water interfaces to form and stabilize a film surrounding air bubbles. Very cold evaporated while milk can be whipped. Gelling/thickening Milk proteins and lactose show high water retention capacity that influences viscosity through thickening and gelling. Stabilizing salts added to evaporated milk in order to avoid protein precipitation during the heat process of sterilization allow excellent gelling properties when heated in sauces, custards and thick puddings. Flavouring/creaming Milk fat possesses a unique flavour which is widely exploited in the manufacture of products known for their richness and quality in taste texture, which cannot be achieved with other fats. For more information on concentrated and dried dairy products, please visit the University of Guelph's Dairy Science and Technology Web site.