SOME FACTORS WHICH INFLUENCE THE FEATHERING 
OF CREAM IN COFFEE 1 
By L. H. Burgwald 
Assistant Market Milk Specialist, Dairy Division, Bureau of Animal Industry, United 
States Department of Agriculture 2 
PLAN OF EXPERIMENTS 
Feathering is the flaking or curdling of cream in coffee. This is some¬ 
times troublesome to milk dealers because customers assume that it 
indicates sourness; and because, although sweet cream when it feathers 
does not produce a sour taste in the coffee, yet it gives an unpleasing 
appearance. It is known that sour cream will feather when added to 
hot coffee, but at times cream that is sweet to the taste will do likewise. 
From this it may be concluded that there must be factors other than 
high acidity which affect or influence feathering. With this in mind 
a number of factors were studied as follows: 
Acidity of coffee made by different methods—boiled, percolated, drip. 
Use of coffees of different grades—high, medium, low. 
Method of mixing cream and coffee— 
(a) Adding cream to coffee without sugar. 
(i b ) Adding cream to coffee and sugar. 
(c) Adding coffee to cream without sugar. 
(d) Adding coffee to cream and sugar. 
Age of cream. 
Kind of cream—percentage of butterfat, and whether raw, pasteurized, 
homogenized, or frozen. 
The acidity of the cream was the basic factor for determining the 
effect w T hich these various other factors had on the feathering of the 
cream. The acidity was determined as lactic acid by titrating with 
N/20 NaOH, using phenolphthalein as an indicator. The conclusions are 
based on results obtained from a total of about 900 different tests. 
ACIDITY OF COFFEE 
Three different methods of making coffee were tried—boiling, perco¬ 
lating, and dripping. 
Boiled. —The coffee was medium ground, 50 grams to 500 cc. of 
distilled water, boiled for five minutes, filtered, cooled, and made up to 
500 cc. 
Percolated. —The coffee was medium ground, 50 grams to 500 cc. 
distilled water, percolated for five minutes, filtered, cooled, and made up 
to 500 cc. 
French drip. —Pulverized coffee, 50 grams to 500 cc. of boiling dis¬ 
tilled water poured through the coffee once, filtered, cooled, and made 
up to 500 cc. 
1 Accepted for publication Nov. 19, 1923. 
3 Credit is due Geo. B. Taylor, former market milk specialist with this division, for preliminary work 
in these experiments. 
Journal of Agricultural Research, 
Washington, D. C. 
aio 
(541) 
Vol. XXVI, No. 11 
Dec. 15, 1923 
Key No. A-68 
