Journal of Oil Palm Research Vol. 2 No. 2 1990 Dec, p. 219-227
X-RAY DIFFRACTION ANALYSIS OF PRODUCTS OBTAINED BY DRY FRACTIONATION OF PALM OIL
Palm oil was dry fractionated by four different methods, namely (1) cooling at 30ºC and (2) at 23ºC for 18 hours with no agitation, (3) cooling at 3ºC for 18 hours with agitation and (4) at 22ºC for 3 hours with agitation. The yields of stearin were 16%, 30%, 26% and 32% respectively. Filtration rates were good when fractionation took place with no agitation but were poorer with agitation. X-ray analysis showed the stearins from methods 1, 2 and 4 to be in the beta-prime form while that from method 3 was in the beta form. These polymorphic forms were stable when the stearins were stored up to 12 days. When the stearins from methods 1 and 2 were tempered at 40º and 45ºC the polymorphic form changed to the beta form. When melted and then crystallized at 0ºC all the stearins crystallized in the beta-prime form. A hydrogenated palm oil crystallized in the alpha form under these conditions.
The short spacing of the beta-prime form of palm oil and palm products is unique in that it shows two distinct lines of strong intensity at 0.43 and 0.41 nm as opposed to one at 0.42 nm reported in other fats. The softening points of the stearins correlated with the C48 triglyceride content but the dropping points did not.
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* Palm Oil Research Institute of Malaysia,
P O Box 10620,
50720 Kuala Lumpur
+ Department of Food Science,
University of Guelph, Guelph,
Ont. Canada NIG 2W1