8 BULLETIN 1190, U. S. DEPARTMENT OF AGRICULTURE. 
EFFECT OF IMMEDIATE AERATION OF THE MILK. 
Proper aeration reduces off flavors and odors in the milk. In 
order to determine the effect of aeration on the flavor and odor of 
milk produced by cows fed from 10 to 15 pounds of green alfalfa one 
ho in- before milking, samples were taken, after which the milk while 
still warm was run over a surface cooler, cooling below 45° F., and 
samples were again taken. In 189 opinions on 53 samples treated 
in this manner, 46 per cent rated the flavor of the milk as normal 
before aeration, while 55 per cent gave the same rating to the milk 
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Fig. 2.— Effect on flavor and odor of milk from feeding 30 pounds of green alfalfa 1, 3, and 5 hours before 
milking. The degree of shading shows the relative intensity of the flavor and odor produced. 
after aeration. Before aeration 19.1 per cent of the opinions rated 
the milk as off in flavor, which was reduced to 9 per cent by aeration. 
Likewise, the number of opinions rating the odor of the milk as 
normal was increased from 35.4 to 47.1 per cent and those rating the 
samples as off were reduced from 25.4 to 16.9 per cent by the same 
process. No great difference was found in the percentage of opinions 
rating the samples as slightly off and very slightly off on either flavor 
or odor. (See Table 7 and fig. 3.) 
