Scientists from Ghent University in Belgium report that applying many of the options outlined in the CIAA’s ‘Acrylamide Toolbox’ were ineffective to reducing acrylamide in par-fried French fries. However, when used in industrially produced chilled French fries, the enzyme asparaginase was effective at reducing levels of the suspected carcinogen.
The study, published in the Journal of Agricultural and Food Chemistry, shows that acetic and citric acid treatments, adding calcium lactate, or applying asparaginase did not affect acrylamide formation under par-frying conditions.
“Since for [chilled French fries] a longer enzyme-substrate contact time is allowed, a total asparagine depletion was observed for the enzyme treated fries after four days of cold storage,” report the researchers, led by Bruno De Meulenaer.
“French fries upon final frying presented acrylamide contents below the limit of detection (12.5 micrograms per kilogram) with no effects on the sensorial properties of the final product,” they added.
Approaches already used by the food industry to help reduce acrylamide levels include converting asparagine into an impotent form using an enzyme, binding asparagine to make it inaccessible, adding amino acids, changing the pH to alter the reaction products, cutting heating temperatures and times, and removing compounds from the recipe that may promote acrylamide formation.
Enzymes such as DSM’s Preventase and Novozyme's Acrylaway, work by converting asparagine into aspartic acid, thereby preventing it from being converted into acrylamide. The effect is a reduction in acrylamide in the final product by as much as 90 per cent.
Many of these techniques are included in the European Food and Drink Federation’s (CIAA) ‘Acrylamide Toolbox’. According to Dr De Meulenaer and his co-workers, however, “to date, no publicly available data exists on the evaluation of the various promising additives/processing aids on their acrylamide mitigation potential when applied on a real French fry industrial processing line”.
The Ghent-based researchers evaluated a variety of additives and process aids in industrially production French Fries. Results showed that, for the production of frozen partially-fried (par-fried) French fries, acetic and citric acid, calcium lactate (Puracal PP FCC, Purac) and asparaginase (Acrylaway, Novozymes) were ineffective at reducing acrylamide, despite earlier promising results from laboratory tests.
When tested in a production line of chilled French Fries, the researchers report that asparaginase-treated products had acrylamide levels below the limits of detection, compared with levels of between 90 and 124 micrograms per kilogram in control French Fries.
“The application of the enzyme in French fries which are par-fried is very limited in the current line set-ups due to the insufficient time allowed for enzyme activity from the dip tank until the par-fryer,” wrote the researchers. “In addition, other drawbacks such as temperature control in the dip tank and safety issues should be considered for asparaginase application,” they concluded.
Acrylamide is a suspected carcinogen that is formed during by heat-induced reaction between sugar and an amino acid called asparagine. Known as the Maillard reaction, this process is responsible for the brown colour and tasty flavour of baked, fried and toasted foods.
Despite being a carcinogen in the laboratory, many epidemiological studies have reported that everyday exposure to acrylamide in food is too low to be of concern.
The compound first hit the headlines in 2002, when scientists at the Swedish Food Administration first reported unexpectedly high levels of acrylamide, found to cause cancer in laboratory rats, in carbohydrate-rich foods.
Since the Swedish discovery a global effort has been underway to amass data about this chemical. More than 200 research projects have been initiated around the world and their findings co-ordinated by national governments, the EU and the United Nations.
Source: Journal of Agricultural and Food Chemistry
2011, Volume 59, Pages 898–906, DOI:10.1021/jf1042486
“Implementation of Acrylamide Mitigation Strategies on Industrial Production of French Fries: Challenges and Pitfalls”
Authors: R.M. Vinci, F. Mestdagh, C. Van Poucke, et al.