Crop breeders get a roasting

Since 2002, huge efforts have been made around the world to find out how it is formed in foods, and how it can be reduced. The results of hundreds of research projects have been co-ordinated by governments, the EU, and the World Health Organisation (WHO).

So, after five years work, what do we know? What does the latest research on acrylamide tell us - where do the 40 or more papers on acrylamide presented at last month's American Chemical Society meeting in Boston take our knowledge of acrylamide?

Well, we know that acrylamide is formed as a result of the Maillard reaction between certain amino acids, particularly asparagine, and the sugars found in foods during high-temperature cooking such as frying, baking and roasting. A wide range of home-cooked and restaurants foods such as bread and fried potatoes and coffee contain acrylamide, as well as many industrially-prepared foods such as potato crisps, biscuits, crisp breads and breakfast cereals.

In a paper presented in Boston, Swiss researchers said they had now found acrylamide in dried fruits - a worrying result since dried fruits are generally dried at relatively low temperatures. Fat has also been incriminated. Researchers from Spain told the Boston meeting that dietary fats made a significant contribution to the formation of acrylamide. Indeed, high levels of fats in roasted almonds may account for half the acrylamide found in this food, they said.

But we also know how to reduce acrylamide as well. Its formation is dependent on time and the temperature of cooking. Thus the EU confederation of food and drinks industries, the CIAA, has produced a 'toolbox' of techniques to help food manufacturers reduce acrylamide in high-temperature cooked foods. As a result the snack industry has cut acrylamide levels in potato crisps by an average of 40%, says Bob Foot at the European Snacks Association.

We are also sure that plant genetics can play a part - different plant varieties produce different levels of asparagine. From the Boston meeting we know that agronomics play a big role, too. Increasing the sulphur levels in soils for wheat crops and reducing nitrogen availability can cut levels of asparagine, say researchers at Rothamsted Research, the UK plant research institution.

But does it cause cancer?

So, five years on, that's essentially what we know for certain. But what we don't know, despite all the work, is whether acrylamide actually causes cancer or not. And if it does, what sort? We know that high doses give rats cancer and can damage their DNA and affect their neurological and reproductive systems. But does acrylamide actually cause cancer in humans?

A study by Harvard University presented in Boston showed that foods containing acrylamide were unlikely to cause breast cancer. And other epidemiological studies have failed to show any increases in the risk of cancer caused by acrylamide in the diet.

So the best we can say for certain is that acrylamide is "probably carcinogenic to humans". And no country has put a figure on the maximum levels of acrylamide permitted in foodstuffs. Instead, the EU recommends that the levels of acrylamide in food should be as low as can be reasonably achieved.

But there is good news. Two global ingredients players have both recently launched versions of the acrylamide-reducing enzyme, asparaginase. DSM claims its PreventASe is the first to be used in a retail product - a Christmas-biscuit maker is about to launch biscuits containing 70% less acrylamide in German supermarkets. And Novozymes has just launched Acrylaway.

Both products claim to convert free asparagine into another amino acid, aspartic acid, which does not form acrylamide.

Other recent work has shown that the common food additive calcium chloride (E509) could also help reduce the formation of acrylamide in potato crisps and fries by up to 95%. Turkish scientists have found that immersing potatoes in a calcium chloride solution before frying can reduce the formation of acrylamide.

And extracts of green tea and bamboo leaf could also reduce acrylamide formation, Chinese researchers have suggested. Even ordinary table salt appears to help, too. Work at the Slovak University of Technology indicates that when acrylamide is heated with salt, the level of acrylamide falls. Salt, it seems, has catalytic properties and accelerates a polymerisation reaction that reduces acrylamide.

Unfortunately coffee remains a problem. A study by the European Commission and Nestlé recently reported that efforts to reduce the acrylamide content of coffee adversely affected its flavour and nutritional benefits.

Professor Bronek Wedzicha is pro-dean of mathematics and physical sciences at Leeds University (UK) and specialises in food modelling. He hopes to have a new UK acrylamide toolbox ready in the next few months that will take a different slant on acrylamide reduction. The work is the result of a two and a half year project for the UK Food Standards Agency involving universities at Reading and Nottingham.

A mathematical model

Unlike other toolbox approaches, Wedzicha's will be a mathematical model that will run on a computer and will take into account food quality. "It will enable anyone to key in specific parameters of a food - its composition, such as the mix of amino acids and additives such as calcium, as well as the way it is being treated. And it will then predict what the acrylamide level will be," says Wedzicha.

"You can reduce acrylamide in your chips by cooking them at a lower temperature. But that doesn't actually give you quite the chip you want. So there is a counterpart to the acrylamide data which is the quality of the food - the flavour and the colour. Our toolbox will embrace this as well."

Wedzicha, who presented a paper on the formation of acrylamide at the Boston meeting, says that if there is going to be a proven harmful effect from acrylamide, then it will be evidence of its link to nerve damage rather than cancer. "The cancer link has not been joined up," he says.

Dr Richard Stadler, head of quality management at Nestlé in Switzerland, chairs the CIAA's toolbox group. The CIAA will definitely be updating its toolbox from the Boston meeting, he says. In particular, he was impressed by the work of Peter Sadd at RHM Technology in the UK into the impact of changing recipes in baking products to reduce acrylamide - such as removing ammonia-based raising agents, for instance, and using longer yeast fermentations. "We will be looking in more detail at recipes and the impact of calcium and magnesium salts, as well as the addition of extra amino acids to the recipe."

But despite all the work presented in Boston, the food industry is still short of academic studies into the effects that all these steps to reduce acrylamide have on food quality, says Stadler. "What is still missing are good organoleptic tests and sensorial evaluations, particularly by academics, to show that the mitigation options (reduction tools) don't have any major impact on the quality of the food."

Bring in the crop breeders

We are not going to remove acrylamide out of the diet, that's clear, says Stadler. "But we have now picked all the low-hanging fruit - we have optimised processes and looked at recipes. Now we need to go one step more, and it is a really important one - we need major changes at the agronomic level.

"We need to look into different varieties. The communication between the food industry and crop breeders needs strengthening. Plant breeding takes many years, so clearly asparagine has to become a major concern for plant breeders, and now."

Stadler's views are echoed by Dr Nigel Halford from Rothamsted who presented his group's work on agronomics at Boston. "The food industry reacted very quickly to the discovery of acrylamide. And it has taken steps to reduce it.

"My question is, is the plant breeding industry reacting with quite the same urgency as the food sector? We need to be reminding plant breeders that they need to be addressing this issue now."

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