3-monochloropropane-1,2-diol esters (3-MCPD) and glycidyl esters (GEs) are toxic, potentially carcinogenic compounds often found in processed palm oil products. These compounds are closely monitored by the palm oil industry. Current target specifications for 3-MCPDs and GEs are typically below 2.5 mg/kg and 1.0 mg/kg, respectively, with more stringent restrictions expected over the next few years.
To meet these specifications, deodorized palm oils (RBD) may require a post-treatment bleach (RBD-B) followed by soft-deodorization (RBD-BD). The bleaching earth used in the post-treatment bleach plays a significant role in the mitigation of 3-MCPDs and GEs. Soft-deodorization utilizes temperatures around 210°C to prevent the reformation of MCPDs and GEs.
At Oil-Dri’s Nick Jaffee Center for Innovation, we employed a range of our bleaching earth products and investigated how they mitigated 3-MCPDs and GEs based on their acidity. Results of different combinations of products in the RB bleach and the RBD-B post-treatment bleach were also compared.
| Bleaching Earth | pH | Acidity |
| Pure-Flo® B80 | 8.4 | None |
| Supreme Pro-Active® | 3.5 | Mild |
| Perform® 6000 | 2.8 | High |
The findings of this study support what is commonly understood regarding 3-MCPD and GE generation. Acidified bleaching clays will reduce GE levels in palm oil. However, the presence of acid in the oil can increase the amount of 3-MCPDs.
3-MCPDs and GEs were mitigated by employing natural to mildly acidified bleaching clays in the first bleach and mildly to strongly acidified clays in the post-treatment bleach followed by soft deodorization conditions.
Of the three clays employed in this study, processing combinations of Pure-Flo® B80 and Supreme Pro-Active® gave the best overall results, mitigating the formation of both 3-MCPDs and GEs.
Based on these findings, a refinery searching for a product to best reduce 3-MCPDs and GEs would benefit from a mildly acidified bleaching product such as Supreme Pro-Active®.
For more information on 3-MCPDs and GEs, contact our technical service team. We are happy to analyze your oil samples and provide optimization recommendations for current and prospective customers.