+168. Cow's milk or Façons Roquefort.+--The supply of Roquefort is automatically limited by the supply of sheep's milk. The sheep gives milk only about five months in the year and at best a scant average of about a pint a day to a sheep. Sheep's milk for cheese-making is not produced, therefore, outside of very limited regions. Some cow's and goat's milk unavoidably finds its way regularly into the industry itself. Attempts were naturally made to substitute cow's milk. Outside the controlled area, factories were established for this purpose. The quality of the product did not equal that of the Roquefort factories, and French courts decreed that the name Roquefort should not be used for such products. Although some local success was obtained, not much progress was made against the intrenched Roquefort industry. Similar attempts to make such a product in Germany[68] were tried on an extensive scale but failed. More recently, under the inspiration of Conn, the United States Department of Agriculture and the Storrs Experiment Station have studied the possibilities of such an industry. Although the work is not completed, the preliminary reports[69] have indicated the fundamental principles which must underlie such development. +169. Outline of making Roquefort.+--Some of the results of these experiments are summarized in the following paragraphs: _Milk._--Clean-flavored fresh milk testing 4-4.2 per cent fat and up to 2.8 per cent casein gives the best results. The milk with a high percentage of cheese-making solids forms a firmer curd, hence works up better in the process than milk of lower quality. _Acidity._--The milk is ripened by lactic starter up to an acidity of 0.23 per cent titrated as lactic acid at the time rennet is added. This gives a firm curd, which drains to the desired water-content but is low enough to prevent the toughening effect of too high acid. A very slight increase in initial acid--1 to 2 hundredths per cent--combined with the rate at which acidity is developing introduces such physical changes in texture as to make the final texture of Roquefort impossible. _Temperature._--Rennet is added at or below 84° F. Every degree of heat adds definitely to the efficiency of rennet. Below 82° F., curdling becomes slower and the coagulum softer and more difficult to drain. The sheep's milk curd is made from 76° to 84° F. but sheep's milk has about twice the cheese solids found in cow's milk. It was found necessary to raise the temperature as high as texture would permit. However, at 86° F. the physical character of the curd tends to become tough or waxy in handling. At 84° F. the curd remains brittle and crumbly. It was, therefore, necessary to keep the curdling temperature down to 84° F. _Renneting or setting._--Rennet at a rate of 3 to 4 ounces of standard liquid rennet to 1000 pounds (10 to 12 c.c. to 100 pounds) was found to give the best curd under experimental conditions.