Unstable antioxidants may hold key to acrylamide reduction
The study, published in the Journal of Hazardous Materials, suggests free radicals formed as oxidation products - like quinones or carbonyl compounds - from easily oxidised antioxidants may cause acrylamide destruction, reducing total acrylamide content in foods.
“Antioxidants inhibited acrylamide formation mainly by their corresponding oxidized forms, through reaction with one of the main precursors of acrylamide formation [by]… decreasing the contents of free asparagines,” wrote the researchers, led by Dr Baoru Yang, of the University of Turku, Finland and the Jinan University, China.
Acrylamide is a known neurotoxin and a suspected carcinogen formed by a heat induced reaction between sugar and the amino acid asparagine. The process – known as the Maillard reaction - is responsible for the brown colour and tasty flavour of baked, fried and toasted food.
In 2002 Swedish researchers found the carcinogenic compound was present at high levels in many foods . The discovery grabbed international headlines, alarming consumers and food safety authorities globally.
Since then acrylamide has been the focus of much research, and had been found in many foods, including, bread, crackers, sweet biscuits, deep-fried products and coffee.
The main focus of research has been on the compound’s effects in humans, and in how to improve production methods in order to reduce or remove acrylamide from foods.
The new research investigated the effects of several antioxidants, and their oxidation products on the prevention of acrylamide formation and the elimination of acrylamide.
The researchers reported that stable antioxidants could not effectively destruct, or inhibit the formation of acrylamide.
The researchers revealed that certain antioxidants added to an acrylamide solution, showed signs of acrylamide elimination - “The less stable the antioxidants, the more acrylamide was destructed,” reported the researchers.
The antioxidants corresponding oxidation products were observed to directly destruct acrylamide, and its precursor asparagines - inhibiting acrylamide formation.
A positive correlation between the carbonyl value and acrylamide formation was also found in a frying oil–asparagine reaction model system - suggesting that antioxidants may also inhibit acrylamide formation by inhibiting carbonyl compound formation in cooking oils.
The authors concluded that antioxidants may inhibit acrylamide formation in high-temperature processing foods, through three mechanisms - destruction of formed acrylamide by their oxidised products, the formation of quinines or carbonyl compounds such as vitamin C which react with the acrylamide precursor asparagines, and inhibit the production of carbonyl compounds produced from frying oil.
“When the antioxidants are oxidizable with difficulty (i.e., stable) at high temperature, they increase the antioxidant capacity of the reaction system and decrease acrylamide destruction; when the antioxidants are easily oxidizable (i.e., unstable) at high temperature, they are oxidized to form more quinones and free radicals to attack acrylamide, which counteracts their antioxidant activity for decrease in acrylamide destruction,” wrote the researchers.
Source: Journal of Hazardous Materials
Volume 182, Issues 1-3, Pages 863-868, doi: 10.1016/j.jhazmat.2010.06.124
“Effect of antioxidants on elimination and formation of acrylamide in model reaction systems”
Authors: S. Ou, J. Shi, C. Huang, G. Zhang, J. Teng, Y. Jiang, B. Yang