Behaviour of PPO during Fractionation of Palm Oil
Kevin W. Smith, Fat Science Consulting Ltd., Bedford, UK, and Krishnadath Bhaggan, Loders Croklaan B.V., Wormerveer, The Netherlands

The physical properties and processing performance of fats are greatly influenced by their triacylglycerol (TAG) composition. Palm fractions are used in many food products. The palm oil mid fraction (PMF) is the highest value fraction and finds its use, amongst other applications, as a confectionery fat, particularly in cocoa butter equivalents (CBE). The principal TAG present in PMF is 1,3-dipalmitoyl-2-oleoyl glycerol (POP). However, the asymmetric isomer, rac-1,2-dipalmitoyl-3-oleoyl glycerol (PPO) also exists in palm oil (and PMF), although at a much lower level. It interacts with POP to alter the melting point, polymorphic behaviour and crystallisation of PMF. In many applications, the effects are undesirable. Thus, a high ratio POP/PPO is often wanted.
PPO levels vary naturally, in palm oil, but may increase during refining of the oil, particularly if high temperatures (e.g. >240°C) are used.
This study examined the fate of PPO during the fractionation (dry and solvent) of palm oils with differing levels of PPO. During fractionation of palm oil to yield PMF, the POP/PPO ratio was improved, but this was possible to a much greater extent when the PPO level was initially lower. While the results show that the selection of appropriate fractionation conditions will influence the POP/PPO ratio, they also emphasise the importance of selecting a palm oil with low PPO content in order to obtain a better quality PMF.