palm oil processing plant with fruit on ground in Cote d'Ivoire, Africa

3-MPCD and GE

General

3-Monochloropropane-1,2-diol (3-MCPD) and 2-monochloropropane-1,3-diol (2-MCPD) are chlorinated derivatives of glycerol. 3- and 2-MCPD and their fatty acid esters are among non-volatile chloropropanols, identified in the late 1970s in the composition of hydrolyzed vegetable protein. Glycidyl esters (GE) are a group of compounds formed from glycidol, an epoxide which is known for its high reactivity. GEs comprise glycidol bound to various fatty acids. Both 3-MCPD and GE are typically found in refined edible oils and can make their way into other processed foods that contain refined oil.

3-MCPD and GEs are usually formed during the high-temperature processing of fats and oils. More specifically, 3-MCPD are formed when lipids interact with chloride ions at elevated temperatures, commonly when salts are used or when hydrochloric acid reacts with residual triglycerides. GEs are formed from the breakdown of diglycerides into glycidol, usually at temperatures above 200°C when glycidol can then esterify with free fatty acids to form GEs.

3-MCPD is classified as a possible human carcinogen (Group 2B) by the International Agency for Research on Cancer (IARC). Animal studies have indicated potential renal toxicity and reproductive toxicity. GEs break down to release glycidol, which has been classified as a probable human carcinogen (Group 2A) by the IARC. It has been shown to cause DNA damage and mutations in various in vitro and animal studies. Refined vegetable oil is a major ingredient in infant formula, it is especially important to minimize 3-MCPD and GEs in oils used infant formula to protect the vulnerable population. Analysis of 3-MCPD and glycidyl ester concentrations in 222 infant formula products produced by 4 different manufacturers and purchased in the United States between 2017 and 2019 was reported (Beekman et al. 2019).

The European Food Safety Authority (EFSA) has suggested an intake of no more than 2 µg 3-MCPD/kg body per day while the Joint Expert Committee on Food Additives (JECFA) has recommended 4 µg 3-MCPD/kg body weight daily.  

Guidance for Industry

Food processors can employ several strategies to reduce the formation of 3-MCPD and GE during processing:

  1. Selection of Raw Materials: Use low-chlorine oils and salts to minimize the availability of reactants for 3-MCPD formation.
  2. Control Processing Condition: Lowering the temperature and shortening oil times during deodorization stage of refining can reduce the levels of both 3-MCPD and GEs.
  3. Addition of Adsorbents: Using substances like activated carbon or bleaching earth can help in adsorbing contaminants.
  4. Chemical Modifiers: Employing certain catalysts to alter reaction conditions and inhibit the formation of 3-MCPD and GE.
  5. Post-Processing Treatments: Techniques such as distillation can help in removing these contaminants from final products.

Information for Consumers to Reduce Exposure

Consumers can reduce their exposure to 3-MCPD and GEs in their diet by opting for unrefined or cold-pressed oils for cooking or as a food ingredient in prepared or packaged foods. Oils labeled as "virgin" or "extra virgin” generally indicate minimal processing and are not subjected to high-temperature refining processes.

Resources