Corresponding the high presence of 3-monochloropropane-1,2-diol esters (3-MCPDE) and glycidyl esters (GE) in refined palm oil, this paper re-evaluated degumming and bleaching processes of physical palm oil refining to reduce the amount of said contaminants. Separation-free water degumming was incorporated into the process, and this significantly (p
Chloride reduction in crude palm oil (CPO) of greater than 80% was achieved with water washing conducted at 90°C. Inorganic chloride content in CPO was largely removed through washing, with no significant reduction in the organic chloride. Phosphorous content of CPO reduced by 20%, while trace elements such as calcium, magnesium and iron were also reduced in the washing operation. The 3-MCPDE formed in the refined, bleached and deodorised palm oil displayed (RBDPO) a linear relationship with the chloride level in washed CPO, which could be represented by the equation y = 0.91x, where y is 3-MCPDE and x represents the chloride in RBDPO refined from washed CPO. In plant scale trials using 5% water at 90°C, mild acidification of the wash water at 0.05% reduced chloride by average 76% in washed CPO. Utilising selected bleaching earths, controlled wash water temperature and wash water volume produced low chloride levels in RBDPO. Chloride content less than 1.4 mg kg-1 in plant RBDPO production was achieved, through physical refining of washed CPO containing less than 2 mg kg-1 chloride and would correspond to 3-MCPDE levels of 1.25 mg kg-1 in RBDPO. The 3-MCPDE reduced further to 1.1 mg kg-1 as the chloride level of washed CPO decreased below 1.8 mg kg-1. Chloride has been shown to facilitate the 3-MCPDE formation and its removal in lab scale washing study has yielded lower 3-MCPDE levels formed in RBDPO. In actual plant operations using washed CPO, 3-MCPDE levels below 1.25 mg kg-1 were achieved consistently in RBDPO.
Chlorinated compounds such as sphingolipid-based organochlorine compounds are precursors for the formation of 3-monochlororopanediol (3-MCPD) esters in palm oil. This study evaluates the effects of several factors within the palm oil supply chain on the levels of sphingolipid-based organochlorine, which in turn may influence the formation of 3-MCPD esters during refining. These factors include application of inorganic chlorinated fertiliser in the oil palm plantation, bruising and degradation of oil palm fruits after harvest, recycling of steriliser condensate as water for dilution of crude oil during oil palm milling, water washing of palm oil and different refining conditions. It was observed that bruised and degraded oil palm fruits showed higher content of sphingolipid-based organochlorine than control. In addition, recycling steriliser condensate during milling resulted in elevated content of sphingolipid-based organochlorine in palm oil. However, the content of sphingolipid-based organochlorine compounds was reduced by neutralisation, degumming and bleaching steps during refining. Although water washing of crude palm oils (CPO) prior to refining did not reduce the content of sphingolipid-based organochlorine, it did reduce the formation of 3-MCPD esters through the removal of water-soluble chlorinated compounds. It was found that the use of inorganic chlorinated fertiliser in plantations did not increase the content of chlorinated compounds in oil palm fruits and extracted oil, and hence chlorinated fertiliser does not seem to play a role in the formation of 3-MCPD esters in palm oil. Overall, this study concluded that lack of freshness and damage to the fruits during transport to mills, combined with water and oil recycling in mills are the major contributors of chlorinated precursor for 3-MCPD esters formation in palm oil.
This paper examines the processing steps of extracting palm oil from fresh fruit bunches in a way that may impact on the formation of chloropropandiol fatty esters (3-MCPD esters), particularly during refining. Diacylglycerols (DAGs) do not appear to be a critical factor when crude palm oils are extracted from various qualities of fruit bunches. Highly hydrolysed oils, in spite of the high free fatty acid (FFA) contents, did not show exceptionally high DAGs, and the oils did not display a higher formation of 3-MCPD esters upon heat treatment. However, acidity measured in terms of pH appears to have a strong impact on 3-MCPD ester formation in the crude oil when heated at high temperatures. The differences in the extraction process of crude palm oil from current commercial processes and that from a modified experimental process showed clearly the effect of acidity of the oil on the formation of 3-MCPD esters. This paper concludes that the washing or dilution step in palm oil mills removes the acidity of the vegetative materials and that a well-optimised dilution/washing step in the extraction process will play an important role in reducing formation of 3-MCPD esters in crude palm oil upon further heat processing.
3-Monochloropropane-1,2-diol (3-MCPD) esters and glycidyl esters (GE) are heat-induced contaminants which form during oil refining process, particularly at the high temperature deodorization stage. It is worth to investigate the content of 3-MCPD and GE in fries which also involved high temperature. The content of 3-MCPD esters and GE were monitored in fries. The factors that been chosen were temperature and duration of frying, and different concentration of salt (NaCl). The results in our study showed that the effect was in the order of concentration of sodium chloride
The reduction of the 3-monochloropropane-1,2-diol esters (3-MCPDE) and glycidyl esters (GE) was successfully achieved by the optimization of four processing parameters: phosphoric acid dosage, degumming temperature, bleaching earth dosage, and deodorization temperature by response surface methodology without the need for additional processing steps. The optimized processing conditions were 0.31% phosphoric acid dosage, 50 °C degumming temperature, 3% bleaching earth dosage, and 240 °C deodorization temperature. The optimization resulted in more than 80% and 65% reduction of 3-MCPDE and GE levels, respectively with color and FFA contents maintained in the acceptable range specified by Palm Oil Refiners Association of Malaysia. The optimized refining condition was transferred to macro scale refining units of 1 kg and 3 kg capacities to investigate its successful application during scale-up process.