Improvement of Keeping Quality of Butteroil by Selective Trace-Hydrogenation and Winterization

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Abstract
The effect of very slight hydrogenation on the keeping quality of butteroil was studied. Under selective conditions of low pressure, low pressure, low catalyst concentration and at HOC such trace-hydrogenation proceeded at a controllable and moderately rapid rate. Samples of deodorized hydrogenated butteroil having I values reduced by 1.4, 2.5, 3.5 and 6.0 units were compared with deodorized unhydrogenated butteroil after storing at 60 C. Both organoleptic evaluation and peroxide number determinations showed hydrogenated samples to have much improved keeping quality. A significant improvement was achieved by reducing the I value by only 1.4 units, whereas a reduction greater than 2.5 units did not result in any further improvement. Butteroil of greatly improved keeping quality may be obtai ned by very slight hydrogenation with only a little loss of unsaturation. The level of unsaturation may be restored by winterization from a solvent such as n-hexane. Analysis of fatty-acid composition of the hydrogenated and unhydrogenated butter oils indicated that the improvement of keeping quality by selective trace-hydrogenation is due to the diminishing of the highly unsaturated fatty-adds such as linolenic and arachldonic acids.