384 EXPERIMENT STATION RECORD. 



tained 73.6, 63.7, 62, and 57.9 per cent, respectively, of moisture 2* hours after 

 cutting, showing that the higher temperatures facilitated the separation of 

 whey. Curds of sweet milk set at 86, 92, 98, and 104°, and heated so that 35 

 minutes after cutting they stood at 104°, differed in moisture content at first but 

 were alike after one hour. Wlien ripe milk was used, from li to 2i hours were 

 required to reach the same results. With milk of lower aciditj' the initial 

 rate of removal of moisture was less than in the preceding experiments. 



Heating the vat to 104° and 110° soon after cutting showed that at both 

 temperatures early and rapid heating caused more rapid separation of whey 

 during part of the first hour, but after the first hour the separation of moisture 

 was slower than when the M'dinary method of heating was used. There was a 

 greater loss of fat in the whey and a smaller yield of cheese from each of the 

 more rajiidly heated vats instead of a larger yield. With milk of a lower 

 acidity the results showe<l that the different methods, of heating had a marked 

 effect on the moistui-e content early in the process, but owing to lack of acidity 

 the curds all practically stopped firming when the moisture content reached 

 about G5 per cent. The differences in moisture content so marked at first were 

 thus lost. 



" Four curds cut with i, f, i, and f in. curd knives, respectively, contained 

 49.7, 52.9, 58.2, and 69.8 per cent of moisture 2^ hours after cutting, showing 

 liow great differences of moisture content are produced by using different 

 knives." 



The rate at which curds lost moisture after cutting was not affected by 

 variations in the proportions of rennet extract between 2 and 6 oz. per 1,000 

 lbs. of milk. It was found, however, that the cheese maker can save time by 

 using more rennet. 



A moderately high acidity induced a rapid separation of moisture. When the 

 acidity was above 0.18 per cent the rate of separation increased but little. 

 Thus, curds made from very sweet or overripe milk retained a larger proportion 

 of moisture than curds from milk of medium ripeness. 



" To insure so far as possible that 0.17 per cent of acid, instead of 0.15 per 

 cent, for example, is present in the whey by the time the curd is firm enough 

 to dip without unnecessary loss of fat, the cheese maker has to judge for 

 himself before adding rennet whetlier acidity is increasing at a suitable x'ate." 



Milk set at 0.19 per cent acidity after pasteurizing gave up its whey at about 

 the same rate as the sweet milk set at 0.17 per cent. There was a slight in- 

 crease of whey acidity in the latter, but none in the former. From this it 

 appears that the rate at which moisture separates from the curd when the milk 

 is pasteurized is abo-ut the same as when the milk is sweet and practically 

 uninoculated with bacteria. 



" Pressure applied to curd in the press, on the rack, or under the whey 

 hastens the separation of whey. On account of the buoying effect of the sur- 

 rounding whey, the pressure of curd cubes on each other when allowed to 

 settle under the whey is too slight to hasten the separation of moisture from 

 curd. If the whey be mostly removed from the vat one-half hour before mat- 

 ting, so as to leave the curd under the pressure due to its own weight, whey is 

 rapidly expelled. A little whey left in the bottom of the vat at this time helps 

 to prevent matting. 



" When curd is piled on the rack its weight is great enough to expel moisture 

 at an increased rate, until the moisture content reaches about 38 per cent. 

 or until the process, is stopi^ed by matting. Stirring a curd on the rack pre- 

 vents matting. When a curd is well stirred its final moisture content depends 

 to a great extent on its acidity." 



