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. 
