C03032/C03036: Exploiting processing factors to reduce acrylamide in cereal-based foods

Study Duration: May 2003 to June 2005

Contractor: RHM Technology Ltd and Brewing Research International

Acrylamide is formed in starch-rich foods that have undergone cooking or processing at a high temperature. These foods include crisps, chips, bread and crispbread. Acrylamide is known to cause cancer in animals and its presence in some foods may harm people's health.

Acrylamide has been classified as a potential genotoxic carcinogen and so levels of acrylamide in food should be as low as reasonably achievable. Further investigation of the relationship between acrylamide and processing techniques could lead to the development of methods of reducing acrylamide in cereal products.

The overall aim of the project is to deliver recommendations on how to achieve minimal acrylamide levels in commercial and domestically prepared cereal-based foods and drink. The study consists of four main objectives:

• extension of analytical methods for acrylamide and potential precursors in foods
• the relationship between key precursors in the raw materials and acrylamide levels formed in foods
• the relationship between processing factors and acrylamide formation
• methods to reduce acrylamide levels in food by altering processing techniques

Project C03032/C03036 was extended in order to investigate the effects of certain processing aids that were shown to increase acrylamide levels in baked cereal products such as cakes and biscuits. Details of the extension (project C03052) can be found at the link below.

Since the discovery of acrylamide in cooked foods, research efforts have focussed on those foods displaying some of the highest levels of acrylamide formed such as potato based products.

Levels of acrylamide in cereal based foods and beverages are generally lower; however, because they are consumed in larger quantities, they can contribute significantly to dietary intake of acrylamide. This project aims to address the gap in our understanding of how natural variation and the effects of processing influence acrylamide formation in cereal based foods and beverages.

Cereal based foods

Levels of acrylamide in commercial bread were found to be quite low; however, acrylamide levels were found to be significantly higher in the crusts of commercial bread.

Biscuits were found to contain a wide range of acrylamide levels, with the highest levels found in ginger biscuits. Results showed that ginger and ammonia (from raising agents) can enhance acrylamide formation in bakery products.

Wholemeal flour was shown to contain more asparagine (a precursor for acrylamide formation) than other more refined flours. Levels of asparagine were found to vary considerably between the different types of wheat that are ground to make flour. The level of asparagine in flour was shown to correlate to the level of acrylamide in the cooked product.

Possible options for reducing levels of acrylamide in cereal based foods include optimising the temperature, moisture and pH and addition of calcium (this is a statutory requirement for bread manufacture, which might explain the low levels of acrylamide observed in commercial bread).

Cereal based drinks

Acrylamide levels were measured in the heat-treated cereals that are used to make cereal based drinks such as beer. These malted cereals were found to contain relatively high levels of acrylamide, and the level of acrylamide was found to be related to the processing temperature and product colour. In some circumstances, acrylamide was formed in heat-treated cereals at temperatures below 100&degC, showing that acrylamide can be formed in cereal products at temperatures lower than that require for acrylamide formation in other foods such as potatoes. The process of malting cereals was not found to affect acrylamide levels.

It was found that heating cereals above 200&degC caused acrylamide to be destroyed. However, this can not be used as method for reducing acrylamide in cereals used to make cereal based drinks because it leads to increased formation of 3-monochloropropane-1,2-diol (3-MCPD), another process contaminant.

Various methods were investigated to reduce levels of acrylamide in cereal based drinks. Addition of calcium salts to cereals before roasting was shown to be effective in reducing acrylamide. This work should be tested on a commercial scale to assess its suitability. Extended stewing (part of the heating process for cereals heated under high moisture conditions) times were found to reduce acrylamide levels and there was some evidence that yeast may degrade acrylamide, but further work is needed in both of these areas before they could be used to develop methods to reduce acrylamide.

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)

Publications:

• Sadd et al. 2005. Chemistry and Safety of Acrylamide in Food. Vol.561, pp.414-430.
• Hamlet et al. 2004. Czech Journal of Food Sciences. 22, 290-293

Presentations given:

• Baxter et al. Sadd et al. Proceedings of the 30th Congress of European Brewery Convention, Prague, 14-19th May 2005.
• Hamlet et al. UK Food Standards Agency stakeholders meeting on process contaminants. 2005.
• Sadd et al. UK Food Standards Agency stakeholders meeting on acrylamide. 2004.