Effect of fractionation conditions and the addition of diacylglycerol on the physico-chemical properties of refined bleached and deodorised palm oil (RBDPO) / Normah Ismail

The effects of fractionation conditions and DP (dipalmitin) addition on RBDPO (refined bleached and deodorised palm oil) fractions (olein and stearin) were studied. RBDPO was fractionated at 14 to 28°C for 90 mm. The collected oleins and stearins were analysed for physico-chemical characteristics, yield, olein entrainment, crystal size distribution and morphology. Oleins were softer during the first 25 to 50 min of fractionation at 14 to 22°C and after 40 mill of fractionation at 26 and 28°C. Stearins produced at 14 to 22°C were softer between 15 to 20 min of fractionation while stearins produced at 26 and 28°C were harder beginning from 60 min of fractionation. Oleins and stearins produced at 14 to 22°C were softer than those produced at 26 and 28'C. Fractionation at 14 to 22°C resulted in rapid crystallisation, softer oleins and stearins, lower olein entrainment, higher count of fine crystals and lower yield of oleins but higher yield of stearins. DP was prepared by glycerolysis and purified by short path distillation (SPD) and fractionation. The optimum processing conditions for DP purified by SPD (DGSDU) were from Raw (110°C) to Res (165°C) to Dis (135°C) with 96.6% of DP in DGSDU and the yield of 9.6% (wlw). The optimum conditions for DP purified by fractionation (DGCHM) were 3.5 hr, 65°C and molar ratio of 2:1 palniitic acid to glycerol with 89.38% DP in DGCHM and the yield of 71% (w/w). DP preparation by fractionation was considered to be a better route due to the ease and shorter period of preparation, higher yield and reasonable concentration. DGCHM was added into RBDPO at 0, 1, 3 and 6% followed by fractionation at 22 and 26°C. Oleins produced with DAG (diacylglycerol) addition were softer at shorter fractionation time than those produced without DAG. Fractionation time has no effect on the physico-chemical properties of stearins. Stearins were harder at higher percentages of DAG addition. Crystallisation was rapid, yield of stearin was higher and crystals were larger while count of fine crystals increased at higher percentages of DAG addition. Fractionation conditions and DP addition were found to affect the physico-chemical properties of RBDPO fractions while DP enhanced the crystallisation of RBDPO.