+122. Milk for Neufchâtel+ should be clean, free from gas and taint. Such milk should preferably be not more than twelve hours old when received and in no case show higher than 0.20 per cent lactic acid by titration. Milk testing 4 per cent fat or higher will produce a higher quality of product than lower grade milk, although every grade from skimmed-milk to cream is used in producing some form of Neufchâtel. This milk should be pasteurized unless shown to be free from tuberculosis by proper test of the cattle. Evidence[38] that the organism of tuberculosis will withstand the regular handling process for cheeses of this group and retain its ability to cause disease in experimental animals makes the introduction of pasteurization necessary in this whole group of cheeses. Any effective pasteurization may be used, but temperatures of 140-145° F. for thirty minutes have been effective with less changes in the milk than higher temperatures for shorter periods. The milk should be cooled to curdling temperature and the starter and rennet added and stirred into the milk in bulk. The milk may then be quickly distributed into the curdling cans with a hose or from the gate valve of the mixing vat. +123. Starter.+--To insure the development of a clean acid flavor, a small amount of lactic starter should be used. The quantity to use depends on the quality of the milk. With skimmed-milk, a pint for each thirty-pound can is recommended by Matheson and Cammack[39] and by Dahlberg. (See page 98.) For whole-milk Neufchâtel, 2 c.c. to a thirty-pound can of milk commonly gives good results. On this basis 2 ounces of starter would be sufficient if properly stirred into about 1000 pounds of milk. Too slow development of acid is preferable to over-rapid souring. +124. Renneting or setting.+--The milk should be cooled after pasteurizing to between 70° and 75° F. Rennet is added at the rate of 1/3 c.c. to a thirty-pound can (roughly 1/3 ounce to 1000 pounds). This will thicken the milk sufficiently in the first few hours to reduce the separation of the cream. For completion of the curdling and souring process, twelve to eighteen hours are required. Usually the cans stand overnight at uniform temperature. When ready to drain, the curd should be firm, smooth and mildly acid. Whey separating from it should not titrate above 0.35 per cent titrated as lactic acid.