Written by Diana Abdi, BS. Gamma-ray radiation increases the amount of saturated fat and decreases the amount of unsaturated fat in beef meat.
One technique to reduce or eliminate disease causing microorganisms, including, Escherichia coli, Campylobacter, Salmonella and Staphylococcus aureus, from foods is with treatment of ionizing energy, also known as, irradiation (2, 3). Of the three types of ionizing treatments permitted (gamma rays, high-energy electrons and X-rays), gamma-ray irradiation is commonly used to improve the safety on a wide range of foods and extend their shelf-life (e.g. delaying ripening in fruits and vegetables) (1,3). The efficiency of gamma-ray irradiation process depends on the organism’s sensitivity to irradiation and the amount of DNA in the target organism (3), as irradiation results in damage to DNA and other cellular structures (1). Currently, over 40 countries (including the US) have been approved of approximately 40 different foods, such as, fruits, vegetables, spices, grains, seafood, meat and poultry, to undergo the irradiation process (3).
Food irradiation has been approved by the FDA as safe and effective in reducing or eliminating harmful bacteria (3). One reason that food irradiation has become of interest in the US, is the increase in food borne diseases which cause an estimated 76 million illnesses, 325,000 hospitalizations, and 5,000 deaths annually (3). The US economy suffers a relatively high loss of an estimated $6.5 to $33 billion to food borne associated diseases (3). Worldwide food production suffers an estimated 25% loss due to infestation, contamination and spoilage, costing the US economy alone, roughly $5 to $17 billion annually (3).
In a recent study in the January 2011 issue of Food Chemistry, researchers studied the effect of gamma-ray irradiation on the fatty acid profile of beef meat (2). Three beef meat samples were studied; non irradiated beef meat (control), irradiated beef meat at 5 increasing doses of irradiation (test), and a commercially available beef sample irradiated at an unknown dose (UN) (2). The effects of gamma-ray irradiation on the fatty acid profile (saturated fatty acids and unsaturated fatty acids) in the triglyceride composition of beef meat was studied using types of chemical tests called nuclear magnetic resonance (NMR) spectroscopy and gas chromatography (GC) (2). Triglycerides are the main form of fat in our bodies including saturated fats that are most detrimental to human health, (such as meat fat, milk fat and butter) and polyunsaturated fats (sunflower, canola, and olive oil) that tend to lower bad cholesterol (LDL) and keep constant levels of good cholesterol (HDL) (4).
Based on the NMR analysis, researchers found that with the 50% increase in irradiation doses, there was a significant increase in the total amount of saturated fatty acids and a decrease in the amount of polyunsaturated fatty acids of the triglyceride composition of the irradiated samples as apposed to the non irradiated beef sample (2). The researchers conclude that the decrease in polyunsaturated fatty acids may be due to the fact that fat-containing foods are sensitive to irradiation (2). These evident changes in the fatty acid composition shown by proton NMR spectroscopy were also confirmed using GC (2). The commercially available beef sample (UN) confirmed to be exposed to irradiation treatment by both NMR and GC techniques (2). Therefore, researchers concluded that the “UN” beef sample serves as evidence of the potential and reliability of NMR technique for identifying irradiated meat products (2).
This study provides evidence that gamma-ray irradiation in beef meat effects the fatty acid composition in triglycerides. Irradiation can not only be used in beef meat, but also in poultry, fruits and vegetables (3). Irradiated poultry and meat products are estimated to cost only 3 to 5 cents a pound more than unirradiated meat (2), and effective to prevent the spread of pathogenic and spoilage microorganisms (2, 3), but does increase the amount of saturated fats.
Source: Stefanova, Rayna, et al. “Effect of gamma-ray irradiation on the fatty acid profile of irradiated beef meat.” Food chemistry 127.2 (2011): 461-466.
© 2011 Elsevier Ltd. Published by Elsevier Ltd. All rights reserved.
Posted April 27, 2011.
References:
- ”Gamma Irradiation”. Steris Isomedix Services. 2007.
- Stefanova, R., et al. “Effect of Gamma-ray Irradiation on the Fatty Acid Profile of Irradiated Beef Meet”. Food Chemistry. 127(2):461-466, Jan. 2011.
- “The Facts About Food Irradiation”. UW Food Irradiation Education Group.
- “Understand the Difference Between Unsaturated and Saturated Fats”. About.com.
6 Oct. 2008.
