Meat irradiation

At low and medium doses, it is well established that the nutritional value of proteins, carbohydrates, and fats as macronutrients are not significantly impaired by irradiation, and neither the mineral bioavailability is impacted. Like all other energy depositing process, the application of ionizing radiation treatment can reduce the levels of certain sensitive vitamins. Nutrient loss can be minimized by irradiating food in a cold or frozen state and under reduced levels of oxygen. Thiamin and ascorbic acid are the most radiation sensitive, water-soluble vitamins, whereas the most sensitive, fat-soluble vitamin is vitamin E. In chilled pork cuts at the 3 kGy maximum at 0-10°C, one may expect about 35 0% loss of thiamin in frozen, uncooked pork meat irradiated at a 7 kGy maximum at —20°C approx., 35 % loss of it can be expected [122]. 

Klinger et al. (31) reported that extensive taste panel tests of chicken breast meat or leg meat irradiated to 3.7 kGy and cooked by boiling in water showed no loss in sensory quality immediately after treatment. The sensory quality of the irradiated chicken deteriorated during refrigerated storage over a period of 3 to 4 weeks. Irradiated chicken breast meat was acceptable for about three weeks however, quality of unirradiated chicken was retained for only about four days during chilled storage. 

The overall yield of radiolysis products is relatively low and their distribution will depend on the fatty acid composition of the triglycerides. In meats irradiated in the absence of oxygen, low levels of the free fatty acid, the associated propanedioldiester, hydrogen, and products derived from the triglyceride radical are to be expected. Much lower yields of volatile hydrocarbons are produced that provide insight into other scission processes and reaction pathways [27, 30, 31],... 

This commonality in the radiolysis was established not only for cooked meats irradiated to high doses at -40°C, but also for raw meats irradiated to lower doses at 77 K [29]. The ESR spectra for raw pork, beef sirloin, and chicken breast (Figure 14) show the singlets associated with radicals formed by electron addition to the carbonyl groups, the yields of which linearly increased with dose. After annealing at -78°C, the spectral features changed to the predominant asymmetric doublet associated with the peptide backbone radical. Moreover, a direct comparison of spectra at -78°C for raw and roasted turkey breasts irradiated to 3.8 kGy showed no differences, indicating that native and denatured conformers of the protein respond radiolytically in similar ways [29]. 

Dependence on total fat. For scission of C-C bonds up to about six carbons from the aliphatic end of the chain, the stable hydrocarbon products formed will be the same for most of the fatty acids. Consequently, the yields of such hydrocarbons as pentane and hexane should be independent of the fatty acid composition but dependent solely on the total fat content of the meat sample. This dependence is seen for several low molecular weight hydrocarbons [14, 62] when their normalized yields in four different enzyme-inactivated meats irradiated at -30°C are plotted against fat content, as Figure 15 illustrates for hexane. 

A characteristic chromatogram from chicken meat irradiated with a 5 kGy dose at a dose rate of 0.9 kGy h is shown in Fig. 7.1. The chromatogram indicates that as well as the characteristic hydrocarbons (1-tetradecene, pentadecane, 1,7-hexadecadiene, 1-heptadecene and 1,8-heptadecene) many non-characteristic volatile compounds have been isolated and detected, which demonstrates the necessity of blank experiments. 

A performance test of cans of irradiation-sterilized meat products (3). 

The metallurgical experiments showed that the beta-alpha transition of the tin coating did not occur at irradiation doses of 3-5 Mrad and 6-7.5 Mrad at 5, —30, and —90°C and that the tensile properties, impact ductility, peel strength of soldered lap joints, and microstructure of commercial tinplate and solder were not affected by the irradiation conditions that are used in the sterilization of meat products. 

Obana, H., Eurata, M., and Tanaka, Y., Analysis of 2-aUcylcyclobutanones with accelerated solvent extraction to detect irradiated meat and fish, J. Agric. Food Chem., 53, 6603, 2005. 

Karam, L.R and Simic, M.G. (1986). Methods for the identification of irradiated chicken meat. Presented at the WHO Working Group on Health Impact and Control of Irradiated Foods, Neuherberg, Germany, November. 

The National Centre for Food Safety Technology, is spearheading several packaging related efforts to expand the fist of polymers that can be used for packaging in food irradiation applications. This comprehensive article explains and describes the current situation in the field of irradiated foods and packaging and provides an update on impending approval for processed and red meats. The industry is concerned to uphold and maintain public confidence in the processed food and irradiated food supply. 

Increase of shelf life under refrigeration and control of pathogenic nonsporeforming bacteria in fresh meat and poultry can be achieved by a 1-3 kGy dose. Doses for irradiation are selected under the consideration of threshold dose levels for sensory changes (off-odor), which depends on the type of animal meat (Table 7) [45]. Off-odor is due to the generation of volatile compounds from lipids and nitrogenous compounds formed by the reaction of these constituents with the reactive species produced by the radiolysis of water. 

Radiation decontamination of meat was first commercially implemented in Brittany, France, when e-beam irradiation treatment was established for frozen slabs of mechanically separated chicken meat [57,58]. 

One of the primary reactions of ionizing radiation with saturated fatty acids is decarboxylation and alkane formation (2). Dimers tend to be produced by reaction of ionizing radiation with unsaturated fatty acids (2). When meats are irradiated C -C 7 n-alkanes, C2-C17 n-alkenes, and C4-Cg iso-alkanes are the predominant products from the lipid fraction (10), Irradiation of the lipoprotein fraction of meat results in the formation of the following volatile compounds Ci-C 7 n-alkanes, C2-C1J n-alkenes, dimethyl sulfide, benzene, and toluene (10). 

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