Irradiation link to trans fats formation dismissed
A report in a forthcoming issue of the Journal of Food Science (JFS) agrees with the US Food and Drug Administration (FDA) conclusions that the use of the radiation processing technique does not induce significant changes in trans fats beyond those brought about by conventional food processing techniques.
Irradiation is a process that exposes foods to ionizing radiation that kills insects, moulds and bacterium and the technology can kill up to 99 per cent of pathogens. It is more widely used in the US than in Europe to improve the microbial safety and extend the shelf life of foods such as spinach, meat, spices, poultry and shellfish.
Trans fats
Though trace amounts of trans fats are found naturally, in dairy and meats, the vast majority are formed during the partial hydrogenation of vegetable oil (PHVO) that converts the oil into semi-solids for a variety of food applications.
While trans fats are attractive for the food industry due to their extended shelf life and flavour stability, scientific reports have shown that they raise serum levels of LDL-cholesterol, reduce levels of HDL-cholesterol, suggesting that consumption of trans fatty acids can increase the risk of coronary heart disease.
As a result there is increasing pressure on food manufacturers to reduce or remove trans fatty acids from their products and reformulate.
Method
The US researchers, as outlined in the JFS article, investigated possible formation and changes of fatty acids in ground beef and frankfurters exposed to irradiation doses of 1 and 5 kGy alongside non-irradiated samples as controls.
After irradiation the ground samples were either frozen or stored at -20°C and 4°C.
The authors claim that the variation in results among previous studies may have been due to differences in methods used, and thus they chose a modified AOAC official method to determine the impact of irradiation on the fatty acids.
Results
They found that, in line with previous studies, C18:1 trans was the dominant fatty acid.
Their study showed that, when expressed as the percentage of total sample weight, the dominant trans fatty acid content was not consistently affected by irradiation at either dose of 1 and 5 gamma rays (kGy).
When expressed as a percentage of total fatty acids, the C18:1 trans, according to the findings, was increased from 3.99 per cent for the control ground beef to 4.05 per cent for the sample irradiated by 5 kGy, and from 1.21 per cent for the control frankfurter to 1.28 per cent for the sample irradiated by 5 kGy
The authors concluded that, taking the variations in trans fatty acids in meats due to season, feed, age of animal, and storage into account, the effect of irradiation on fatty acid composition at the doses tested was minimal.
Source: Journal of Food SciencePublished online ahead of printTitle: Formation of trans fatty acids in ground beef and frankfurters due to irradiationAuthors: Fan, X; Kays, S.E.
