Report on the Agricultural Experiment Stations, 1951 Page: 74
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74 REPORT ON EXPERIMENT STATIONS, 1951
ventional steps in the preparation of butter oil. By adding such
surface-active agents as Tergitol 7 or Ahcowet-RS, it was possible
to quickly break the natural oil-water emulsion in milk and obtain
a high quality butter oil.
Water-Insoluble Acids in Butter
Much attention has been given to developing a simple accurate
method of determining the WIA (water-insoluble acids) in butter,
since the amount of these acids is now serving as an index of the quality
of cream used in the manufacture of commercial butter. The Indiana
station found that the WIA reading is influenced as much as 100
percent by the amount of alkali used in neutralizing the ether-water
solution in the present test.
The Illinois station calls attention to the fact that added glucose
markedly reduces the rate of WIA formation in cream. The station
inoculated sterilized cream with Geotrichum candidum: and found that
between 4 C. and 37 WIA formation was in direct proportion to
the incubation temperatures but that lactic acid inhibited the production
of water-insoluble acids. A sample of cream which soured
rapidly generally contained less water-insoluble acids than a sample of
cream in which acid developed slowly. The assay of samples by
both the newly recommended method and by the earlier Hillig method
indicated that some error results from variation in butterfat color.
By adding formaldehyde to suppress microbial growth, the Iowa
station demonstrated that the natural milk lipase causes an increase
in both WIA and butyric acid values. Holding cream at low temperatures
may prevent acid defects as a result of bacterial action, but
increased fat hydrolysis occurs owing to stimulation of lipase activity.
Knowledge of these factors which alter the rate of formation of WIA
should assist creamerymen in producing more marketable butter.
Dairy technologists at the Kansas station noted that cream separated
from milk known to be susceptible to spontaneous oxidation had lower
WIA numbers than cream from milk that did not develop an oxidized
flavor. The Nebraska station found that organoleptic grading of
cream did not consistently result in a high or low WIA value. Usually
the WIA content of butter was slightly lower than the WIA content
of the cream from which it was churned.
Expansion of the cream layer of fluid milk by the illegal practice of
adding reconstituted superheated condensed milk depends on the
presence of fine curd floccules in the cream. The Oklahoma station
demonstrated how this fraud can be detected and what changes in the
cream line can be brought about by different techniques.
No difference in the growth-promoting properties of milk fat from
different breeds or from cows fed on different rations were discovered
in an experiment carried on by the California station. A slight difference
was found when the fat was fractionated into three portions by
precipitation from a solvent at -20 F., -53, and filtrate remaining
at -53. Rats fed the -53 filtrate generally showed greatest
growth, and those fed the -20 fraction the least gains. Substituting
a 2-percent linoleic acid for an equal amount of -20 precipitate did
not improve its growth-promoting properties.
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United States. Office of Experiment Stations. Report on the Agricultural Experiment Stations, 1951, book, January 1952; Washington D.C.. (https://digital.library.unt.edu/ark:/67531/metadc5991/m1/76/: accessed April 23, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.