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Process Contaminants in Fats and Oils

Commonly known as 3-MCPD, 2-MCPD, and Glycidyl Esters (GE)

References

 

Process Contaminants

Process contaminants are a group of unrelated compounds formed in the production of finished food products. Of particular interest is the occurrence of variable levels of 3-MCPD esters in refined vegetable oils (see description below). Discrepancies among different measurement techniques have hindered the assessment of levels of contamination.

Although AOCS has favored solving this analytical problem using direct approaches, AOCS members recently adopted 3 indirect methods for determination of 3-MCPDs, 2-MCPDs, and glycidol in edible oils and fats in a collaborative study using defined reference materials. Other process contaminants include pyrrolizidine alkaloids and acrylamide.

AOCS Provides Validated Methods for MCPD Ester Analysis

A collaborative study conducted by AOCS in 2012-2013 with 20 participants from eight countries has validated three indirect methods for characterizing 3-MCPD- (or monochloropropane-1,2-diol), 2-MCPD- and glycidyl-esters in oils and fats. Read more.

  • AOCS Official Method Cd 29a-13
    Fatty acid esters of 2-chloropropane-1,3-diol (2-MCPD), 3-chloropropane-1,2-diol (3-MCPD) and glycidyl esters in edible oils and fats determined through step-wise acid conversion followed by derivatization and measurement by GC/MS.
    Fatty acid esters of 2-chloropropane-1,3-diol (2-MCPD), 3-chloropropane-1,2-diol (3-MCPD) and glycidyl esters in edible oils and fats determined in parallel using alkaline-catalyzed alcoholysis in hypothermic conditions and measured by GC/MS.
  • AOCS Official Method Cd 29b-13
    Determination of Bound Monochloropropanediol- (MCPD-) and Bound 2,3-epoxy-1-propanol (glycidol-) by Gas Chromatography/Mass Spectrometry (GC/MS)
    Fatty acid esters of 2-chloropropane-1,3-diol (2-MCPD), 3-chloropropane-1,2-diol (3-MCPD) and glycidyl esters in edible oils and fats determined in parallel using alkaline-catalyzed alcoholysis in hypothermic conditions and measured by GC/MS.
  • AOCS Official Method Cd 29c-13
    Fatty-acid-bound 3-chloropropane-1,2,diol (3-MCPD) and 2,3-epoxi-propane-1-ol (glycidol), Determination in Oils and Fats by GC/MS (Differential Measurement)
    Fatty acid esters of 3-chloropropane-1,2-diol (3-MCPD) and glycidyl esters in edible oils and fats determined through alkaline-catalyzed hydrolysis using sodium-based reagants and measured by GC/MS.

The collaborative study data were presented by the Chair of the Uniform Methods Committee at the last AOCS Annual Meeting. View "Current status of MCPD and Glycidol Analysis in Oils" (.pdf)

3-MCPD (3-monochloropropane-1,2-diol) in its free state—a potential carcinogen—is a contaminant of acid-hydrolyzed vegetable proteins and soy sauce. 3-MCPD esters have been identified in a number of foods and food ingredients, including refined vegetable oils.

  • 3-MCPD can be formed or lost during the process of extraction if strict protocols are not followed.
  • Methods of analysis rely on gas chromatography/mass spectrometry analysis of "total 3-MCPD" after saponification of the full spectrum of 3-MCPD mono- and diesters. These methods require the use of isotopically labeled standards.

A related process contaminant, glycidyl (glycidol) esters, has been reported. Glycidyl esters have been found in some oils, causing the temporary suspension of supply of these products to the marketplace. AOCS published a collaboratively studied direct method for GE analysis in 2012 (AOCS Official Method Cd 28-10).

AOCS sponsored the comparison of the indirect determination of MCPD-E and GE using reference samples of known composition in 2012. Three model methods were compared and method precision data were calculated. The results were presented at the 2013 Annual Meeting of the AOCS in Montreal in May 2013. The AOCS Expert Panel and the AOCS Uniform Methods Committee recommended the consideration of all three methods as AOCS Official Methods for adoption. The methods were officially adopted in August 2013 and are now available.

EFSA Report and Responses

 

Portions of this page have been developed by AOCS Technical Services in cooperation with ILSI Europe as a deliverable from the ILSI Europe Workshop on 3-MCPD Esters in Food Products, held February 5-6, 2009, in Brussels, as part of AOCS' commitment to help industry and our constituency develop the analytical tools and resources needed to meet this global challenge.