The formation rate of acrylamide was reduced by 56 and 32 per cent when the model system included the bamboo leaf and green tea extracts, respectively, wrote the researchers in the Journal of Food Science .
The study, led by Yu Zhang from Zhejiang University, adds to an earlier study by the same research group reporting the potential of bamboo leaf extracts to reduce acrylamide, hailed at the time as a "pioneer contribution on the reduction of acrylamide in various foods by natural antioxidants" ( Journal of Agricultural and Food Chemistry , doi: 10.1021/jf062568i).
Acrylamide is a carcinogen that is created when starchy foods are baked, roasted, fried or toasted.
It 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.
The new study used a model asparagine-glucose system, with or without the bamboo leaves and green tea extracts on the formation of acrylamide when the mixture was heated at 180 degrees Celsius by microwave.
Bamboo lead extract, with the main components characterised as flavonoids, lactones and phenolic acids, is listed as a food ingredient in China, and permitted as an additive in a range of food products, including fish and meat products, edible oils, and puffed food.
Zhang and co-workers report that both extracts effectively reduced acrylamide formation, achieving a maximum reduction rate when in the range of 10 -6 milligrams of extract per millilitre.
A detailed kinetic study showed that the extracts were affecting the formation rate constants by 56.4 and 32.3 per cent for the bamboo leaves and green tea extracts, respectively.
No effects were observed with respect to the elimination rate of acrylamide, stated the researchers.
In attempting to explain the observations, the researchers stated: "3-aminopropionamide, a transient intermediate formed via decarboxylating reaction of asparagine, is an important and direct precursor contributing to the formation of acrylamide.
Addition of antioxidants may block the oxidation of 3- aminopropionamide."
"Further studies in this domain will focus on the kinetic behavior of acrylamide affected by addition of natural antioxidants in some representative food matrix models such as a potato-based model," they concluded.
This study was financially supported by National Natural Science Foundation Council of China (NNSFCC).
Source: Journal of Food Science Published on-line ahead of print, doi:10.1111/j.1750-3841.2007.00619.x "Reduction of Acrylamide and Its Kinetics by Addition of Antioxidant of Bamboo Leaves (AOB) and Extract of Green Tea (EGT) in Asparagine-Glucose Microwave Heating System" Authors: Yu Zhang, T. Ying, Y. Zhang