606 ANNUAl. REPOKT OF THE Off. Doc. 



ii dositaltlo I'oiuiitiou. boiausc in tbo choosoniakiuu provosss we whuI 

 to iuovriii du' separaiiDU o( lUv tat I'loin (lio luilU as iiuu h as pos- 

 siblo. la ilu' siH-oiul i)la('i\ tlu> siirriug helps auv subslain'i's with 

 odors to osi-ape from tho milk, ospociallv tlu' so-oalliHl animal odor 

 and auv othors iliai mav have boou absi>rbod from the air. 



(2.) Aoratioii" Milk. — Stirring milk while eooling is one method of 

 exi)osini; it to the air, that is. atMaiinji ilu> milk. The airaiiiiu". as 

 well as the i-ooling, lan be advaiKageouslv aeeomplished bv using 

 special forms of apparatus designed for the purpose. The most 

 eouimou form of aerator is a strainer-like tin vessel with holes in the 

 bottom. It is held in pi>sition somewhat elevated above the milk 

 ean bv an iron frame. The milk, as soon as drawn, is strained i«ito 

 this at onee and the milk falls in tiuely-divided drops or streams 

 through the air before going into the ean. The Star cooler and 

 aerator allows the milk to tlow in a thin film over a corrugated nu^tal 

 surface: the cooling is caused ai ilu' same time bv having cold 

 water tlow through (he ai)paratus. \\ hile the more common practice 

 is to cool and aerate o«»lv night's milk, it is desirable that morning's 

 milk should be similarly treated. It is also desirable that the two 

 milkings should be kept separate and not taken to the factory in 

 the same can, unless the morning's milk is cooUhI to the temperature 

 of the night's milk before mixing. 



As soon as milk has been cooled and aerated, it should be covered, 

 iu order to prevent evaporation from the cream layer. If much evap- 

 oration takes place, the layer of cream becomes somewhat tough 

 and does 4u>t mix back readily into the milk. This is objectionable 

 for two iwiisons. (a) the loss of fat is apt to be larger in cheese- 

 making, and (b) it is more dillicult to obtain a representative sample 

 for testing. This dit^icultv nsuallv occurs onlv with night's milk, 

 hut can verv easilv be obviated. 



48. Detection of Injurious Ferments in Milk. 



It is extremely important at times to find out whether milk is fit 

 for eheese-nmking, especially, w here troubles have been experieuceii 

 with fernu^itations that make it ditlicult or impossible to produce 

 good cheese. At the Wisconsin Experiment Station a simple method 

 known as the "Wisconsin curd test," has been devised for detecting 

 milks that are undesirable for cheese-making. Specially designed 

 apparatus can be obtained at dairy-supply houses, but is not neces- 

 sary. The test consists iu making a small chutik of cheese-curd 

 from milk in a glass jar. Take pint fruit-jars and perforate the 

 covers with a few small holes. Before using, clean them in boiling 

 water. A sample of each of the milks to be tested is placed in a 

 jar, nearly filling the jar, and the jar is placed iu water warmed to 



