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Anhydrous Milk Fat: 3. Fractionation Aspects

M. K. Keogh and A. C. Higgins
Irish Journal of Food Science and Technology
Vol. 10, No. 1 (1986), pp. 35-46
Stable URL: http://www.jstor.org/stable/25558124
Page Count: 12
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Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Anhydrous Milk Fat: 3. Fractionation Aspects
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Abstract

Dry fractionation of milk fat i.e. without solvent, is commercially important because the separated fractions have different properties which increase their use range in other foods. Experimental conditions were investigated with the objective of yielding fractions with slip points ranging from 21.0°C to 42.0°C. The effect of raw material variability on the fractions was established. The properties of the fractions were described by slip point, yield, crystal size, percent solid fat and distribution of total fatty acids. Each processing treatment, namely initial temperature (IT), final temperature (FT), cooling rate (CR) and agitation time at the final temperature (AT), influenced the results obtained. The effect of FT and AT on the properties of the fractions was much greater than IT and CR. FT had the greatest influence and accounted for 67.4% of the variability of the hard-fraction slip point and 82.0% of the variability of the soft-fraction slip point. As AT increased, the yield of hard fraction increased except at the lowest FT where yield was already high at the beginning of agitation. The FT required to produce a hard fraction of slip point 42.5°C ranged from 19°C for a hard winter anhydrous milk fat (AMF) to approximately 28°C for a soft summer sample. The yield from the hardest winter AMF was 27.5% which was about twice the yield from the summer AMFs. The physical and chemical characteristics of the fractions were interrelated. The highest correlation obtained (+0.94) was for the slip point and percent solid fat at 35°C of the hard fraction. Percent solid fat levels and the ratio of C18:1 to C18:0 fatty acid levels were significantly related to the yield of both fractions. The slip points of the fractions could not be predicted from the percent solid fat of the parent AMFs.

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