The following score card for judging ice cream has been prepared by the Wisconsin Experiment Station: Flavor, 40; body and texture, 20; bacteria, 20; fat, 10; appearance and color, 5; package, 5.
Fermented Milk Drinks.--Within recent years several forms of milk drinks which have undergone a lactic acid fermentation have come to be extensively used for human consumption. These various forms of buttermilk are all rich in food nutrients since they are made from some form of milk, but they are chiefly valu able as an aid to digestion and in the treatment of certain forms of intestinal disorders. They are found on the market under a variety of trade names such as kefir, kumiss, zoolak, matzoon, yogurt, leben, etc. All these products are the result of changes caused by the action of certain types of micro-organisms. In some of them, as in common buttermilk, the fermentation is caused by the action of the common lactic acid bacteria (Bact. laths acidi) in splitting up the milk sugar and forming lactic acid. Normally from 0.6 to 0.8 per cent of acid is formed. This type of buttermilk may result as a by-product of the ordinary process of but ter-making or it may be made artificially by inoculating milk with a *starter)) of lactic acid bacteria. After the milk is coagulated, it is churned to give it a smooth creamy consistency, then held at a low temperature to prevent further bacterial growth or deterioration in flavor. Most of the commercial fermented milks are made with cultures of Bacillus but paricus, a type of lactic acid organism originally Introduced from Bulgaria, but which has re cently been found to be common in milk in this country. A culture of B. bulgaricus is added to either skimmed or partly skimmed milk from which the miscellaneous flora present in the raw milk has first been eliminated by pasteurization, In this way, a more uniform product of high quality can be secured. After standing at the creamy texture and then bottled and kept cold until needed for use. The B. btagaricus is capable of producing a much higher percentage of acidity than is Bact. lactic acidi, 2 to 3 per cent being not uncommon. It also gives a flavor which is preferred by many persons. Another type of product is represented by the kumiss and kefir in which there is an alcoholic as well as a lactic fermentation, the former being caused by the action of certain species of yeasts, which may develop 1 or more per cent of alco hol. Carbonic acid gas is also developed, causing these products to be decidedly effervescent.
Condensed Milk.— Some of the difficult problems in handling market milk are due to the facts: first, that it is bulky and, therefore, expensive to handle and transport; second, under normal conditions its life is not more than two or three days; and, third, its produc tion is not constant throughout the year, result ing in periods of shortage and surplus. To overcome these difficulties large amounts of milk are now being condensed. This method was first used in America by Gail Borden in 1856, his first plant being in Connecticut. At first the industry grew very slowly, but in recent years its development has been very rapid and it now represents one of the im portant branches of the dairy industry. In 1914 the output of condensed milk in the United States amounted to 875,507,438 pounds, with a money value of $58,870,609. In general there are two kinds of condensed milk, known as sweetened and unsweetened. The first is made by condensing, about 2% to 3 parts of milk to one part of finished product and the addition of about 40 per cent of cane sugar. In the second 2 to 234 parts of milk are condensed to one part and no sugar is added. The removal of water is accomplished by the milk in partial vacuum, the milk usually being heated to 160° F. or higher in an open tank before being
run into the vacuum pan. In the sweetened product the sugar is added to the milk in this open heating tank. The condensing is usually i done under a pressure of about 25 inches and at a temperature of 130° to 160° F. This makes it possible to remove the water rapidly without imparting very much cooked flavor to the finished product. When it has reached the desired degree of concentration it is removed from the vacuum pan and run into suitable containers for marketing. That which is designed for household use is put into hermeti cally sealed tin cans, while for the wholesale trade milk cans or barrels may be used. While the sweetened condensed milk is not sterile it will keep for considerable lengths of time be cause of the inhibiting effect of the high con centration of the milk solids and the added cane sugar upon the growth of the few micro organisms it contains. The unsweetened prod uct is sterilized after the cans are sealed by treatment in a steam sterilizer, where it is sub jected to pressure and a temperature well above the boiling point for from one to two hours. After being taken from the sterilizer the cans are placed in a mechanical device and shaken violently, for the purpose of breaking up any particles of curd which may have formed and to give the milk a smooth creamy consistency. Richmond gives the composition Considerable quantities of both the sweet ened and unsweetened condensed milk are used for household purposes, especially in hot cli mates where fresh milk cannot be easily secured. Large amounts are used in the army and navy and for ocean voyages. That which is put up in bulk is used for manufacturing purposes, chiefly by bakers, candy and ice cream makers.
Powdered Milk.— Powdered milk is made by the more complete removal of moisture than in the case of condensed milk. The objects sought by this process are similar to those for which condensed milk is made; namely, reduc tion in volume and cost of transportation and an increase in keeping quality. Two distinctly different methods are in use for making pow dered milk. In one the partly condensed milk is dried on the surface of a heated revolving drum, and in the other it is sprayed or atomized into a current of heated air. In the former method the dried milk is scraped from the sur face of the drum by means of knives, then ground into flour. In the latter method the moisture escapes as the minute particles of milk fall through the hot air, and the finished product collects on the floor of the drying chamber in the form of a very fine powder. Powdered milk is made from milk with differ ent percentages of fat and also from skim milk.
Powdered milk is not entirely sterile, but since it normally contains not more than 3 to S per cent of moisture bacteria cannot grow in it. If properly protected against moisture it will keep for a long time. Its chief uses are for cooking and for the making of candies and ice cream, for which purpose its small bulk and excellent keeping quality make it especially valuable. By the reincorporation of the proper amount of water powdered milk may be made to resemble normal fresh milk.
Malted Milk.— Is made from whole milk and the liquid obtained from a mash of ground barley, malt and wheat flour. Small amounts of sodium chloride, sodium bicarbonate or potassium bicarbonate may be added. This product is then dried until it contains not more than 3% per cent of moisture. Its keeping properties are similar to those of powdered milk. Malted milk is largely used in the artit &la' feeding of infants. See FARM MANAGE MENT.