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Observations on the Fat Globules in Milk

Published online by Cambridge University Press:  27 March 2009

W. F Cooper ,
W. H Nuttall  and
G. A Freak
W. F Cooper
Affiliation:
The Cooper Laboratory for Economic Research, Watford.
W. H Nuttall
Affiliation:
The Cooper Laboratory for Economic Research, Watford.
G. A Freak
Affiliation:
The Cooper Laboratory for Economic Research, Watford.
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Extract

Results of our previous work were published in the Journ. of Agric. Sri., IV, 1911. There, also, a brief summary of the chief papers published on the subject of the fat globules was given, to which it is unnecessary to refer in detail here.

When the work was first commenced in 1909, the problem before us was the consideration of the variation in the size of the fat globules, with relation to churning, as regards the different breeds of cattle. The breed was considered because it was usually supposed that this was one of the chief factors which influenced churning. The most definite result of our work was that it was shown that consideration must be given to the character of the milk, irrespective of the breed. This conclusion is quite contrary to that of other workers, but an examination of their figures shows, undoubtedly, that this is actually the case: the results given by Woll (Digestion Expts., Seventh Annual Report, Agric. Expt. Stat, Wisconsin, 1890, 238; also Agric. Sci., 1892, vi, 445) emphasise this point particularly. It is also shown by this year's work, as may be seen from Tables V–XI.

The comparative size of the globules has been worked out very thoroughly by Gutzeit, who measured the mean volume of the globule. Other workers give their results as “relative sizes.” In our work we attempted to ascertain the distribution of the fat in the globules, and to this end the number of globules of each size was determined, and curves were drawn. The result of this, however, was negative. At that time we were considering the breeds of the cows from which the milks were obtained; had we considered them solely as milks of a certain mean size of globule, much more might have been achieved.

An apparatus was devised to give an absolute figure for the churnability of any cream, but, until the effect of the other factors has been determined, it is impossible to interpret the results. Some experiments to ascertain the optimum temperature were described also.

Type
Research Article
Information
The Journal of Agricultural Science , Volume 5 , Issue 3 , June 1913 , pp. 331 - 356
Copyright
Copyright © Cambridge University Press 1913

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References

page 333 note 1 In the English literature, where the subject of globules is dealt with, reference is given chiefly to D'Hont's paper (“Essai sur les dimensions du globule graa en suspension dans le lait. Influence de la race.” Courtrai, 1890). This is remarkable since a work has been published by Gutzeit (Landwirtsch. Jahrbikher, XXIV. Berlin, 1895, 539—668) which is very exhaustive, and which is based on a very large number of actual measurements.

page 340 note 1 The other figures cannot be given.

page 343 note 1 Woll (Sixth Ann. Report, Agric. Expt. Stat., Wisconsin, 1889, 71) also fed his cows 3 or 4 weeks, before changing the fodder.

page 344 note 1 It would be well to emphasise, once more, the futility of attempting to judge either of the average size of the globules or of the fat content in a milk, by visual examination. It must not be supposed that a field full of small globules contains more fat than one with a small number of large globules; or vice versa; determination alone can decide this.

page 345 note 1 In our work published in 1911, p. 163, the centres of gravity of the curves A were given as representing the mean diameters. These are to be calculated from the number of globules in the area counted, and the percentage of fat. This will be rectified in due course. The use of the word “mean” was incorrect, and should have read “average.” The distinction between these two terms, and their significance, is considered in detail in the account of the mensuration of the globules, p. 372.

page 345 note 2 An important, and a very disconcerting source of error was experienced. The fat was determined in a centrifugal apparatus, using the amyl alcohol and sulphuric acid method. The milks, at first, showed great discrepancies. The tubes were then standardised, using a milk checked by the Adams method, and the following correction factors were found necessary:—1·03, 1·23, 1·18, 1·06, 1·10, 1·04.