264 Milk and Its Products. 



pint glass jars as there are samples of milk to be tested and clean 

 and sterilize them as described above. Fill each jar two-thirds full of 

 the milk to be tested, label them plainly and put them up to the neck 

 In a tub or vat of water heated to 98° F. When the milk has reached 

 the temperature of the water add ten drops of rennet extract to each 

 jar, and mix it with the milk by shaking the jar. Allow the jars to 

 stand until the curd is firm and then cut the curd finely with a case 

 knife. When the curd has settled pour o£f the whey and allow the 

 curd to settle again till a second portion of whey can be removed, 

 The best tests are made when the removal of whey is as complete as 

 possible. The jars containing the curd are then covered and again 

 placed in the tub and the temperature maintained as nearly as pos- 

 sible at 98° F. for six to 12 hours, when they may be examined. A 

 solid, firm curd, without disagreeable odor or flavor, shows that the 

 milk is pure and clean and has been properly handled. Impurities 

 in the different samples are indicated by the presence of small 

 round holes (gas cells) seen in the curd when it is cut across with 

 a knife, or by various disagreeable odors that may be detected when 

 the covers to the jars are removed. The apparatus for this test in 

 an improved form is now furnished by most of the dairy supply 

 houses. 



MONRAD ReXKET TeST. 



This test is figured and described on page 173. It is used as fol- 

 lows: To determine the ripeness of milk for cheese making, put 

 5 c. c. commercial rennet in a 50 c. c. flask and fill with water to 

 the mark. Put 200 c. c. of milk at 86° F. in a suitable tin cup, and 

 allow it to float in the vat. Add 5 c. c. of the diluted rennet, and 

 note carefully the time required for the first appearance of coagu- 

 lation. The time required will depend upon the amount of milk 

 and rennet used, the strength of the rennet, the temperature and 

 the ripeness of the milk. All except the last remaining constant 

 from day to day, the degree of ripeness is measured by the time 

 required for coagulation. The riper the milk the shorter the time; 

 ordinarily from one and one-half to two minutes will be required. 

 The diluted rennet must be made fresh every day. 



Marschall Rennet Test. 



For a description and cut of this test, see page 174. Directions for 

 its use: To determine the ripeness of milk for cheese making, fill 

 the vessel to the o mark with milk, add a pipette full of commercial 



