Genetic improvement of wheat to reduce the potential for acrylamide formation during processing.

The formation of the chemical contaminant, acrylamide, during high-temperature cooking and processing of wheat, rye, potato and other mainly plant-derived raw materials was reported in 2002, and the presence of acrylamide in foods is now recognized as a difficult problem for the agricultural and food industries. Acrylamide causes cancer in laboratory animals and is therefore considered to be probably cancer-causing in humans. It also affects the nervous system and reproduction. Cereals, of which wheat is the most important, generate half of the acrylamide in the European diet, with biscuits, snacks and breakfast cereals being of particular concern. The FAO/WHO Expert Committee on Food Additives has recommended that dietary exposure to acrylamide should be reduced and the European Commission is expected to issue guidance values on acrylamide levels in food before the end of 2010. The current draft of the guidance values proposes levels that will not be consistently achievable for many products. The proposed guidance level for breakfast cereals, for example, is 400 parts per billion (ppb), while levels in some wheat-based breakfast cereals are over 1000 ppb. Furthermore, many Member States support these guidance values becoming regulatory limits. The food industry therefore requires both short-term solutions and a long-term programme of reduction in the acrylamide forming potential of wheat in order to comply with this regulatory situation as it evolves. Methods for reducing acrylamide formation during processing have proven to be difficult to apply to wheat products, either being ineffective or having an unacceptably adverse effect on product quality. The development of commercially viable wheat varieties that are low in acrylamide-forming potential but retain grain characteristics that are important for end product quality would help to address, at source, the problem of acrylamide formation in food manufacture, catering and home cooking, without the need for additives or potentially costly changes to processes. The high-temperature degradation of an amino acid, asparagine, in the presence of sugars (glucose, fructose and maltose) has been shown to be the major route for acrylamide formation and the limiting factor in wheat products is free asparagine. Wheat contains significantly higher levels of asparagine than most other grains. Furthermore, whole wheat grain and wheat bran, which have important health promoting properties, tend also to have higher asparagine levels than refined wheat flour. This project seeks to identify currently available varieties and genotypes of wheat that are low in asparagine and provide wheat breeders with the genetic tools to reduce the concentration of asparagine further. This application is being submitted through the BBSRC's stand-alone LINK scheme. The project will benefit from the involvement of a major European/GB wheat breeder and a consortium of wheat supply chain businesses, allowing for the identification and review of key targets by the industrial partners. The level of industry support is indicative of the importance of the acrylamide issue to wheat supply chain businesses and the potential impact of the project. A letter of support has also been provided by the Food Standards Agency. The project will use state-of-the-art techniques for analysing amino acid concentrations in wheat flour, exploit the genetic resources in wheat that have been developed at Rothamsted and the John Innes Centre, including mapping populations, wheat genetic modification (as a research tool) and high-throughput screening of mutant populations, and utilise the latest DNA sequencing techniques to study differences in gene expression between high and low asparagine genotypes. The impact of reductions in acrylamide-forming potential of grain on performance in industrial processes will be assessed by food industry partners.

This LINK project involves groups from Rothamsted Research, the John Innes Centre and wheat supply chain businesses. It addresses the formation of the contaminant, acrylamide, during high-temperature cooking and processing of foods. Cereals generate half of dietary acrylamide. The European Commission is about to issue guidance values on acrylamide levels in food and the current draft proposes levels that will not be achievable for many products. Methods for reducing acrylamide formation during processing are difficult to apply to wheat. Attention has therefore turned to the raw material, wheat grain. The thermal degradation of free asparagine in the presence of reducing sugars during the Maillard reaction is the major route for acrylamide formation and the limiting factor in wheat is free asparagine. This project will identify genotypes of wheat with 'high' and 'low' acrylamide-producing potential. The site for synthesis of the free asparagine that accumulates in wheat grain under normal and stress conditions will be identified. Metabolite and gene expression profiles will be obtained to compare a low asparagine DH line, SR3, with one of its parents, variety Spark; these genotypes differ in grain asparagine concentration by 40 %. This will identify the enzymes and genes that determine free asparagine concentration in wheat grain. QTL for free asparagine concentration that are being identified within a current PhD project (ends 2010) will be narrowed. Genetic markers for low free asparagine concentration will be identified. Targeted mutagenesis and genetic modification will be used to change the activity of key enzymes and produce very low asparagine genotypes. The impact of reductions in grain asparagine on performance in industrial processes will be assessed by industrial partners. The programme builds on substantial previous work and will be facilitated by the availability of mapping and TILLING populations, and support provided by industrial partners.

The formation of acrylamide during high-temperature cooking and processing of plant-derived raw materials was reported in 2002 and the presence of acrylamide in foods is now recognized as a difficult problem for the agricultural and food industries. Acrylamide is classified as probably carcinogenic to humans, based on its carcinogenic action in rodents; it also has neurological and reproductive effects. Cereals, of which wheat is the most important, generate half of the acrylamide in the European diet, with biscuits, snacks and breakfast cereals being of particular concern. This project will identify currently available varieties and genotypes of wheat that are low in free asparagine and provide wheat breeders with the genetic tools to reduce the concentration of free asparagine further. The effect of reductions in acrylamide-forming potential of grain on performance in industrial processes will be assessed by food industry partners. The project will generate new knowledge and understanding of the genes and processes that control asparagine accumulation in wheat. Other outputs will be the development of QTL and gene-specific markers for use in breeding programmes, and the production of new, very low asparagine genotypes. The project focusses on wheat but it is anticipated that the knowledge and understanding gained in this project will be applicable to other cereals, such as rye, barley, oats and maize. Potential beneficiaries include: Consumers. Dietary intake of acrylamide is estimated to be approximately 0.3 to 0.6 microgram per kg of body weight per day, with the intake for teenagers and children being higher on a per bodyweight basis. The FAO/WHO Expert Committee on Food Additives has recommended that dietary exposure to acrylamide should be reduced. Wheat producers. Wheat contains significantly higher levels of asparagine than most other grains, including rice and maize, meaning that raw material substitution is an option for food processors. Not a lot of rice or maize is grown in the UK. Food processors. The European Commission is expected to issue guidance values on acrylamide levels in food before the end of 2010. The current draft of the guidance values proposes levels that will not be consistently achievable for many products. The guidance level for breakfast cereals, for example, is 400 parts per billion (ppb), while a recent survey by CEEREAL found acrylamide levels in some wheat-based breakfast cereals to be over 1000 ppb, with the 95th centile at 465 ppb. Furthermore, many Member States support these guidance values becoming regulatory limits. The food industry therefore requires both short-term solutions and a long-term programme of reduction in the acrylamide-forming potential of wheat in order to comply with this regulatory situation as it evolves. Regulators. The project will give an indication of how low asparagine can be reduced to in wheat grain, and the range of concentrations in current varieties. This will help regulators to set reasonable and achievable targets for acrylamide formation in wheat products. The data generated in the project will be disseminated through publication in the scientific literature and presentation at international and national conferences. While publication will be subject to any necessary delay to allow appropriate Intellectual Property (IP) protection, in accordance with BBSRC guidelines, delays will be kept to a minimum. Data relating to the QTL and adjacent genetic markers will be made available using databases being developed for the MONOGRAM cross-institute programme. The populations developed as part of the project will be made available via the JIC Genebank and listed as a public resource on the WGIN (Wheat Genetic Improvement network) and MONOGRAM web sites. Knowledge transfer to breeders, end users and other stakeholders will be facilitated by partiparticipation of CEEREAL, HGCA, ACFM and SNACMA.