On adding warm morning milk to cold evening milk no development of rancidity was detectable with blend temperatures of 40°F., 50°F., and 60°F., but was apparent at a maximum rise of 70°F. Under conditions simulating every-other-day pick-up no significant increase in rancidity occured on raising the blend temperature to 60°F., but a measureable increase did occur with a blend temperature of 70°F. The increment in acid degree values between 24 and 48 hours is much less with every-other-day pick-up than with samples picked up daily.

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Author notes

Dr. VanDemark received the Ph. D. degree in Bacteriology from Cornell University in 1950. Since that time he has served on the staff of the Laboratory of Bacteriology within the Department of Dairy Industry. During that period he has taught elementary microbiology and his research interests have been in bacterial physiology as well as dairy and food microbiology.