C03017, C03018 and C03019: The origin and formation of 3-MCPD in foods and food ingredients

Study Duration: April 2001 to February 2004

Contractor: Central Science Laboratory, Institute of Chemical Technology, RHM Technology, Brewing Research International

3-monochloropropane 1,2-diol (3-MCPD) is a carcinogenic contaminant of acid hydrolysed vegetable protein (acid-HVP), producing genotoxic intermediates on metabolism such as epoxide glycidol. Recent toxicological studies carried out in the UK by the European Union�s Scientific Committee for Food (SCF) and the Joint WHO/FAO Expert Committee on Food Additives (JECFA) have lead to a recommended provisional maximum Tolerable Daily Intake of 2 &#181g/kg/bodyweight/day for 3-MCPD.

In view of this toxicity the European Commission adopted a regulatory limit of 0.02 mg/kg for 3-MCPD in soy sauce and hydrolysed vegetable protein (HVP).

After a survey of foods formulated both with and without acid-HVP, a number of common food ingredients were found to contain 3-MCPD that had previously not been suspected of containing HVP. In particular, 3-MCPD was quantifiable most frequently in samples of malt and malt-based ingredients.

Despite its widespread occurrence, mechanisms of 3-MCPD formation have not been studied in foods other than HVP. Developments in analytical techniques now permit the detection of low levels of 3-MCPD and thus its formation can be studied in both model systems and foods.

This project will allow the Food Standards Agency to formulate advice and recommend strategies to food manufacturers that can be used to reduce 3-MCPD formation during food storage and processing, while assisting the Agency in discussions about domestic and EC legislation for 3-MCPD in foods and ingredients.

The project will aim to:

• Determine the kinetics of 2- and 3-MCPD production and breakdown in model systems.
• Determine the factors affecting the formation of 3-MCPD during the roasting of cereal grains and of other roasted foods, such as coffee.
• Determine the factors affecting the formation and stability of 2-and 3-MCPD in model and whole doughs during the baking process.
• Determine the factors affecting the production of 3-MCPD in a number of meat products, salted fish and cheese products identified as containing detectable levels of 3-MCPD.

The following were the key findings:

Model systems
Production of 3-monochloropropane-1,2-diol (3-MCPD) in food model systems suggested that in foods containing little water (<15% water), glycerol was the major precursor of 3-MCPD during high temperature processing, while in higher water content foods, lecithin became a more significant precursor.

Commercial emulsifiers, based on partial glycerides were found to act as 3-MCPD precursors.

In contrast with 2-MCPD, 3-MCPD was unstable at neutral and alkali pH.

The addition of small quantities of reducing agents such as, glutathione and cysteine, were effective at limiting 3-MCPD production.

Malts
Longer heating times and lower maximum temperatures were shown to produce desirable high colour in crystal malts while maintaining low 3-MCPD levels.

Baked products
The kinetics of 3-MCPD production during baking and roasting of cereal matched the kinetics observed in model systems.

Major precursors in dough were concluded to include phosphatidyl glycerol, glycerol and diacetyl tartaric acid ester (DATEM).

Other factors which contributed to 3-MCPD in baked dough were lipase activity which released 3-MCPD from its esters.

Structure appeared to have no part to play in the production of 3-MCPD in cereal, although the different lipid composition of the germ in wheat and barley did account for some of the observed differences in 3-MCPD production between these two cereals.

Oil extracted from savoury crackers was shown to contain high levels of esterified 3-MCPD, which was rationalised as a potential source of free 3-MCPD during cracker production/storage.

Meat, dairy and smoked products
Salami oil contained significant amounts of esterified 3-MCPD although no evidence could be found to show that the action of lipases, present in the spices, bacterial culture, and endogenous to the meat were responsible for the increase in free 3-MCPD during storage.

Obvious precursors of 3-MCPD production in processed cheese could not be identified. Migration of 3-MCPD from packaging material was considered a possibility for some processed cheeses and salami and the release of 3-MCPD from esters by endogenous lipase activity during storage was not ruled out.

Roasted coffee
Studies on roasted and green coffee aqueous extracts suggested that a number of both high and low molecular mass components in coffee were capable of destroying 3-MCPD in roasted barley.

The final report is available from the Agency's Information Centre.

To obtain a copy, please contact the Enquiry Desk, Information Services, Food Standards Agency (tel: 020 7276 8181/8182 or email: infocentre@foodstandards.gsi.gov.uk)

Contact: For any enquiries concerning this research project, please contact the relevant Programme contact or email: science@foodstandards.gsi.gov.uk