Food irradiated, identification

The technique of EPR spectroscopy has proved to be a non-destructive technique with the potential for the quick and easy identification of a number of irradiated products. However considerable research is still required into products such as Crustacea, exotic fruits and various spices. There would also appear to be considerable potential in the identification of irradiation in a number of packaging materials providing additional identification which would reinforce the results of other techniques. This should help to reassure the consumer and ensure that the technique of food irradiation is not abused. 

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. 

One of the standardized methods, electron spin resonance (ESR) technique, permits identification of food that contains a hard, dry matrix, e.g., bone. When food containing bone is irradiated, free radicals are produced and trapped in the crystal lattice of the bone, which can be detected by ESR spectroscopy [137]. Thermoluminescence of contaminating minerals for detection of radiation treatment of, e.g., spices and dried fruits can be successfully applied [138, 139]. Another standardized method that has been developed for identification of irradiated fat-containing foods is the mass-spectrometric detection of radiation-induced 2-alkylcyclobutanones after gas-chromatographic separation [140]. The... 

Heide, L. Mohr, E. Wichmann, G. Bogl, K.W. In Health Impact, Identification and Dosimetry of Irradiated Foods, Institut fiir Strahlenhygiene des Bundesgesundheitsamtes Miinchen, ISH-Heft, 1988,125,176. 

Some requirements for an identification procedure of irradiated food... 

When bone is treated with ionising radiation, free radicals are trapped in the crystal lattice of the bone (Gordy etal., 1955) and consequently can be detected by EPR spectroscopy. Prior to its application for the identification of irradiated food, the technique was used to date archaeological specimens (Ikeya and Miki, 1980) and as an in-vivo dosimeter to determine the level of human exposure to radiation (Pass and Aldrich, 1985). 

The ultimate proof that the EPR method is useful for the identification of irradiated food is its performance in blind trials. A number of studies have already been completed (Table 5), and the results have been very encouraging. In the majority of cases it has been possible to identify foods treated with irradiation at doses well below those likely to be used commercially. In trials reported by Desrosiers etal., 1990, Scotter etal., 1990, Desrosiers, 1992 and Schreiber etal., 1993 all irradiated and non-irradiated samples were correctly identified. In the more extensive trial reported by Raffi etal., 1992, the numbers of correct identifications depended on the foods examined and the doses applied. In this trial the results for meat bones, dried papaya and dried grape were good but those obtained with fish bones and pistachio nuts were not as conclusive as the results from the trial reported by Schreiber etal., 1993. However further development of the protocols involved with these products has been undertaken and the results from future trials on these products should be more acceptable. 

Following the success of these collaborative trials, standard methodologies for the application of the EPR method for the identification of irradiated meat bones, fish bones and some fruits have been prepared and are about to be submitted to the European Committee of Normalization. At the time when these trials were carried out there was not sufficient information available to permit inclusion of Crustacea among the products being examined and thus validation of the method for the identification of these irradiated foods has to be undertaken. 

Desrosiers, M.F. (1989). Gamma - irradiated seafoods Identification and dosimetry by ESR spectroscopy. J. Aerie. Food Chan. 37. 96. 

Raffi, J., Agnel, J.-P and Ahmed, S.H. (1991b). Electron spin resonance identification of irradiated dates. Food Technol. 3/4. 26. 

Raffi, J., Stevenson, M.H., Kent, M., Thiery, J.M. and Belliardo, J.-J. (1992). European intercomparison on electron spin resonance identification of irradiated foodstuffs. Int. J. Food Sci. Technol. 27. 111. 

Stevenson, M.H. (1992). Progress in the identification of irradiated foods. Trends Food Sci. Technol. 3, 257. 

Rahman, R., Matabudall, D., Haque, A.K., and Sumar, S. 1996. A rapid method (SEE-TLC) for the identification of irradiated chicken. Food Research International, 29 301-7. 

Raffi J., Methods of identification of irradiated foodstuffs and relative products, in "Handbook of food analysis", Nollet L. (ed), 2nd edition, Marcel Dekker/CRC Rress, 2004,1919-1940. 

Plants produce a variety of chemicals to survive attacks by microbial invasion (Grayer and Harbome 1994). These metabolites are either preformed in the plant (prohibitins) or induced after infection (phytoalexins). Since phytoalexins can also be induced by abiotic factors such as UV irradiation, they have been defined as antibiotics formed in plants via a metabolic sequence induced either biotically or in response to chemical or environmental factors. Many of these substances have been identified as flavonoids (Cowan 1999). Extraction of flavonoids and identification of their antimicrobial activity is useful not only for finding new drugs but also for obtaining natural products useful as food additives to improve the shelf life and safety of foods. In fact, an aliment can be deteriorated by spoilage bacteria, that cause and develop unpleasant odours, taste and texture, whereas foodbome pathogenic bacteria may cause diseases with flu-like symptoms such as nausea, vomiting, diarrhoea, and/or fever. Food additives with antimicrobial activity can be used to overcome such problems, but consumers tend to reject the present use of additives obtained by chemical synthesis flavonoids, as additives derived from natural products, can be a valid and preferred alternative (Cowan 1999). 

Demertzis and co-workers [48] carried out an in-depth study of the influence of gamma irradiation on the formation of solvent extractable radiolysis prodncts of flexible films and sheeting for food packaging. The packaging, which was made from PE, PP, polyethylene terephthalate (PET), PS, polyvinylchloride (PVC) and polyamide (PA), was subjected to Co irradiation at a dose of 44.0 kGy. Separation and identification of extracted compormds were carried out using GC-MS and compositional changes in the radiolysis prodncts quantified by calibration using MS detector response. 

GC/FT-IR can be used for amino acid profiling with tert-butyldimethylsilyl derivatization, for the investigation of food-packaging materials, the analysis of biologically active wheat straw extracts with allopathic activity, that of cis- and traws-octadecanoic acids in margarines and of sugar units in disaccharides, for the identification of small molecular migrants extracted from y-irradiated plastic laminates or the radiolysis products of y-irradiated medazepam solution. 

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