Generation of 3‐monochloro‐1,2‐propanediol and related materials from tri‐, di‐, and monoolein at deodorization temperature

Heating tests of pure tri-, di-, and monoolein (TO, DO, and MO, respectively) with and without the addition of tetrabutylammonium chloride as a chloride source at 240°C revealed the characteristic reactions that generate 3-monochloro-1,2-propanediol-related materials (3-MCPD-RM) in each acylglycerol. 3-MCPD-RM were formed mainly from DO and MO, with only a small amount from TO. Glycidyl ester was the predominant class of 3-MCPD-RM generated from both DO and MO, and was increased continuously throughout the heating period with comparable rates in both DO and MO, which also generated 3-MCPD esters with chloride in a short completion time with an achieved level that was fourfold higher for MO than for DO. The production of free glycidol and 3-MCPD was confirmed only in heated MO, but not from TO and DO, in a closed heating system, although these compounds were never detected in oils heated under simulated distillation conditions using a gas stream. In a closed system, both free glycidol and 3-MCPD were increased throughout the heating period, which differed from the esters. Since an interesterification reaction, which produced free glycerol, was observed only in heated MO, free glycerol might be one of the precursors for those free forms. For clarification, further investigation is required.