METHODS OF EXAMINING MILK 227 



be permitted to adhere to the stopper or to the sides of 

 the bottle. If the bottle has been standing for several 

 hours and the milk has been thoroughly chilled, it may 

 be necessary to warm the sample in order to avoid this. 



Color, Consistency, Odor, and Taste. As a prelim- 

 inary examination, the color, consistency, odor, and taste 

 of the milk should be observed. The senses of smell and 

 taste soon tire, however, and it is therefore not possible 

 to properly examine many samples consecutively. 



A bluish tinge may indicate a low per cent, of fat, 

 skimming, or watering, but it must be remembered that 

 any milk will have a bluish tinge if in a thin layer. A 

 reddish tinge is sometimes observed in milk from an 

 udder affected with mastitis. Various other changes in 

 color may occur as the result of bacterial action (see 

 page 71). 



Thin or watery milk is an indication of dilution with 

 water or of skimming. Flakes or curds are present in 

 milk from an udder affected with mastitis. Other changes 

 in consistency are caused by bacteria (see pages 67 and 

 69). 



Abnormal odors may be absorbed from the atmos- 

 phere or may be caused by bacteria (see pages 29, 30, 

 67 and 71). 



A salty or bitter taste is present in mastitis and indi- 

 gestion, also near the end of lactation and just before 

 parturition. A bitter, metallic taste may be due to rusted 

 milk vessels. Milk may also have an abnormal taste 

 as a result of the growth of certain bacteria, the absorp- 

 tion of gases, and from other causes ( see pages 28 to 30 

 and 66 to 71). Heating milk will make an abnormal 

 odor more pronounced. 



