Journal of Oil Palm Research Vol. 32 (1) March 2020, p. 103-116
ARE CHARACTERISTICS OF SOFT PALM STEARINS SIMILAR TO SOFT PALM MID FRACTIONS?
Published Online: 17 January 2020
The aim of this assessment was to determine the variation between soft palm mid fractions (sPMF) and soft palm stearins (sPOs) which are the co-fractions (solid fractions) obtained from two different fractionation processes which yield palm olein of iodine value (IV) 60. The sPMF and sPOs are not governed by any official standard specifications and are traded based on contractual specifications. Furthermore, the physical and chemical characteristics of sPOs lack documentation as it falls into the general category of palm stearin. Hence, users who are unaware of the differences between these two fractions are misinformed and misguided, leading to dysfunctional application of these fractions in food products. This assessment of sPMF and sPOs evaluated the triacylglycerol composition, fatty acid compositions (FAC), IV, dropping point (DP), solid fat content (SFC) profiles and thermal behaviours in order to establish parameters which can be used as quality qualifiers, which are able to distinctively discriminate both fractions. The triacylglycerol compositions differed significantly between sPMF and sPOs. sPMF contained high amounts of monounsaturated triacylglycerols ranging from 61.83% to 80.07% with 1,3-dipalmitoyl-2-oleoyl-glycerol (POP) ranging from 43.53% to 55.95%. Lesser amount of monounsaturated triacylglycerols were present in sPOs, ranging from 55.56% to 57.33% (POP from 38.36% to 41.81%). The trisaturated triacylglycerols ranged from 2.45% to 5.41% in sPMF and higher values were detected in sPOs ranging from 10.46% to 18.52%. SFC profiles of sPMF and sPOs varied significantly. The sPMF exhibited a sharp decrease in the percentage of solids from 20°C to 30°C which were not exhibited by sPOs. The DP of sPMF ranged between 24.3°C to 31.8°C and sPOs varied between 40.3°C to 50.1°C. sPMF and sPOs exhibit unique and distinctive crystallisation and melting profiles which can be used to differentiate these two fractions. Fatty acid composition and iodine values exhibited overlapping values, hence, are inadequate indicators to differentiate these fractions. The assessment concludes that triacylglycerol composition, DP, SFC profile and thermal behaviour (crystallisation and melting) are indicative parameters that are able to assist in differentiating the physical and chemical characteristics of sPMF and sPOs.KEYWORDS:
* Malaysian Palm Oil Board, 6 Persiaran Institusi, Bandar Baru Bangi, 43000 Kajang, Selangor, Malaysia.