A new refining approach for production of refined palm oil with reduced contents of 3-monochloropropane-1,2-diol esters and glycidyl esters

With the recent launch of a new legislation on the maximum limit of glycidyl esters (GE) in food products, the maximum limit of 3-monochloropropane-1,2-diol esters (3- MCPDE) in oil is expected to be introduced soon. Therefore, devising strategies to mitigate these carcinogenic esters in refined palm oil is of urgent priority now. This research aimed to firstly, revise the pre-treatment steps in palm oil refining (degumming and bleaching) in order to minimize the formation of 3-MCPDE and GE in refined, bleached, deodorized palm oil (RBDPO); and secondly, to develop and optimize a new refining approach for the production of high quality RBDPO with reduced 3-MCPDE and GE contents. For the first objective, water degumming that requires no centrifugation and decanting was incorporated into the refining process (1.0% water (w/w), 90 °C, 10 min). This modification successfully reduced 23% of 3- MCPDE and 13% of GE in RBDPO significantly (p < 0.05). Next, six types of bleaching earth (BE) were dosed at 0.5%, 1.0% and 1.5% (w/w) to evaluate their effects on the esters contents in RBDPO. Results showed that high dosage of BE did not promote the maximum reduction of esters contents in oil. Instead, each type of BE had their own optimal dosage to work against the esters. Pore structure, which is a typical performance indicator of BE, was unable to explain the varying capabilities of BE to control the esters formation. The surface acidity of BE was a more accurate performance marker instead. Acid-activated BE (AABE) was found to have greater esters reduction effect as compared to natural BE. AABE of low surface acidity (pH ≃ 5) was found to be excellent for the production of RBDPO with the least amounts of 3- MCPDE and GE, while AABE of high surface acidity (pH ≃ 3) was found to greatly promote the formations of 3-MCPDE and GE. The modified refining method was optimized by using response surface methodology to produce RBDPO with minimum 3-MCPDE, GE and FFA contents and lowest oil color, with water dosage (0.5-1.5%), acid dosage (0.04-0.08%), pre-treatment temperature (60-90 °C), deodorization temperature (240-260 °C) and duration (80-120 min) as the independent variables. Among all, deodorization temperature was the most critical factor that significantly affected all responses (p < 0.05). High pre-treatment temperature was found to exert considerable impact on the formation of both esters (p < 0.05), by which it significantly promoted the formation of 3-MCPDE and simultaneously decreased the formation of GE at its high level. Other than this, the interaction effect between acid and water dosage strongly impacted 3-MCPDE content too. An optimum and verified model was obtained, which resulted in 78% reduction for 3-MCPDE and 53% of reduction for GE, as compared to RBDPO that was refined conventionally. The efficiency of the new refining method was assessed on four grades of crude palm oil as the third objective of this study. Similar esters mitigation effect was observed across all grades of oil, thus confirming the ester mitigation efficiency of the new refining approach.

Text FSTM 2020 3 - IR.pdf Download (1MB)

Actions (login required)

View Item