The cream may be churned at once if sweet cream butter is desired, or ((ripened" or soured. The aim of ripening is to develop certain flavors in the butter, and a certain degree of acidity which aids in churning and influences the texture. Since the discovery that the changes which commonly take place in milk are due to the action of micro-organisms, it has become a part of the butter maker's task to make use only of such organisms as will aid in his work, and eliminate those which tend to impair the product. It has been found that the flavor of butter depends in very large degree upon the kind of bacteria which accomplishes the souring of the cream preliminary to churn ing. The scientific butter maker, therefore, prepares a ((culture) of the beneficial bacteria, keeping it free from all others. In the usual pro cedure of butter-making on the farm, a "starter,k) used to start the acid fermentation in the newly skimmed cream, is saved from the preceding batch of sour cream, or from the buttermilk of the preceding churning. This naturally con tains a mixture of many bacterial ferments, and too often a large proportion of those which are injurious to butter quality. It is advisable to make the starter out of sweet skim-milk, two or three gallons for each 10 gallons of the cream to be soured. Place it in a covered vessel in a temperature between 75° to It will require from 18 to 24 hours to become thick. It should be distinctly but pleasantly acid. The top inch should be rejected, as it contains the undesirable bacteria. It is not always easy to obtain the starter from the milk of a mixed herd. In this case it is best to make the starter from the milk of one cow chosen after experi ments as to which milk makes the finest flavored butter. Or, as is the habit in many dairies, a pure culture may be purchased (by mail) from the nearest agricultural experi ment station and a established from that. One of the essentials in making good butter is the proper care of the cream after churning: if it is to be churned the next day it should be mixed at once with the starter and placed in a temperature of 65° to 70°. If it is to be churned the second day, it should be cooled to 55° to 60° ; and if not till the fourth day, it should be cooled to 40° F. Warm cream, fresh from the separator, should never be added at once to the cooled cream: it should first be cooled to the proper keeping temperature. The starter should be mixed in at such a time that the cream will reach the desired degree of acidity by the time it is desired to churn. The degree of acidity may be determined by various tests. The most effective acidity is from 0.6 to
0.7 per cent. When possible it is advisable to pasteurize the milk or cream. This is accom plished by heating the milk or cream to 145° F. for 30 minutes, then rapidly raising it for a moment to and then as rapidly cooling it to 75° or 80°. This destroys about 98 per cent of all the bacteria. It does not, however, de stroy the spores, and when making pure cul tures of lactic acid bacteria, it is the rule to repeat the pasteurization daily for four days. Into the pasteurized cream is stirred the starter, 18 to 24 hours before the churning is planned, the cream meanwhile being held at a tempera ture of 52° to 54° in summer, and 58° to 62° in winter. The cream should be strained into the churn, and the churn should be not more than one-third full. A box or barrel churn is the best, and the churning should not be too fast, the idea being to keep the liquid measurably in one •body which is thrown forcibly from one end of the churn to the other. In the dasher churns much of the cream is overchurned, pro ducing a greasy butter. When the granules of butter are fairly uniform in size and have the general appearance of cracked corn, the churn ing is done. It takes about 30 minutes. The buttermilk should be strained away, and the butter washed with about the same quantity of water as there was cream in the beginning. Too much water will yield a tasteless butter. The butter is then to be worked by pressure, never by a rubbing motion, which destroys the grain. A wedge-shaped or square butter-worker is preferable. The butter is usually salted im mediately after washing, and before working, the amount of salt used being about one and one-half ounces to the pound of butter. When the washing is done in the churn, the salt is sometimes added in the form of brine composed of one pound of salt to two pounds of water for each 10 pounds of butter. The churn is then set in operation for two or three minutes, and the butter is allowed to stand 15 minutes in the brine before working.
The most common defects of farm-made butter are: (1) Rancidity, due to the cream being too old, or too sour, or having been kept too warm before churning; (2) foul flavor, from having been allowed to absorb bad odors; and (3) umottles," from buttermilk being worked into the butter instead of having been worked out. Scrupulous cleanliness and atten tion to details from the feeding of the cows to the placing of the product on the market are imperative. See idurrra WORKER; CHURN;