The gas-producing organisms enter because of unclean conditions somewhere in the handling of the milk and the making of the cheese. Some of the common sources of gas organisms are: (a) unclean milkers; (b) dirty cows; (c) aërating the milk in impure air, especially air from hog-pens where the whey is fed; (d) allowing the cows to wade in stagnant water or in mud or in filthy barnyards and then not thoroughly cleaning the cows before milking; (e) exposing the milk to the dust from hay and feed; (f) dirty whey tanks; (g) drawing milk and whey in the same cans without afterward thoroughly washing them; (h) unclean utensils in the factory; (i) using gassy starter; (j) ripening cheese at high temperatures.
Some of these causes are within the control of the cheese-maker after the making process is begun. Many of them are avoided only by eternal vigilance. Among the recommendations for meeting gassy curd are the following: use only milk produced under clean sanitary conditions; use a clean commercial starter.
If gas is suspected in the milk, a larger percentage of commercial starter should be used. More acid must be developed before the whey is removed. If the gas shows while cheddaring, the curd should be piled and repiled until the holes flatten out before milling.
The curd should be kept warm during the piling or cheddaring process. This may be accomplished by covering the vat and setting a pail or two of hot water in it. After milling, the curd should be stirred and aired for a considerable length of time before salting. This will aërate the curd and allow it to cool. The cheese should then be placed in a cool curing-room. (See handling of gassy milk.)
259. Acidy, pasty or soft body and texture.—A cheese with acidy body may be either hard and dry or soft and moist. It has a mealy or sandy feeling when rubbed between the fingers. The causes and remedies are the same as for cheeses with acid flavors. When rubbed between the fingers, it is pasty and sticks to the fingers. It is caused by the cheese containing too much water. (See control of moisture.)
260. Defects in color.—Any color which is not uniform is a defect. The proper color depends on the market requirement. Some markets prefer a white and others a yellow cheese; however, if the color is uniform, it is not defective.
Mottled color is a spotted or variegated marking of the cheese. Several causes may give the same general effect: (a) uneven distribution of moisture, the curd having extra moisture being lighter in color; (b) neglecting to strain the starter; (c) adding the starter after the cheese color has been added; (d) mixing the curd from different vats.
Remedies for this mottled color are: (a) to maintain a uniform assimilation of moisture (see discussion of moisture); (b) to strain the starter to break up the lumps before adding to the milk; (c) to add all of the starter before adding the cheese color; (d) not to mix curds from different vats.
Seamy color.—In "seamy" colored cheese, the outline of each piece of curd may be seen. There is usually a line where the surfaces of the curd come together. It may be caused by the pieces of curd becoming greasy or so cold that they will not cement. This may be remedied by having the curd at a temperature of 80° to 85° F. when put to press. If it is greasy, this may be removed by washing the curd in cold water.
Acid color.—This is a bleached or faded color and is caused by the development of too much acid. (See acid flavor for causes and remedies, [page 266.])