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Biomedical subjects

J Raffi

Publications and source records attributed to J Raffi.

12 recordsLinked to original sources
PubMed2002

Electron paramagnetic resonance of radicals induced in drugs and excipients by radiation or mechanical treatments.

Radiation as well as mechanical treatments induced in drugs and excipients radicals, which can be studied by electron paramagnetic resonance. A special attention is pointed about the use of electron paramagnetic resonance (EPR) to bring the proof whether or not a drug has been irradiated or not. We also discuss of other methods (thermoluminescence (TL), gas phase chromatography (GPC)) which can be used to bring the same proof in case of irradiated drugs, excipients and cosmetic products.

Amino Acids↗
PubMed2001

Photodegradation of cassava and corn starches.

The baking expansion properties of sour cassava starch (Polvilho azedo) are attributable to photochemical starch degradation induced by heterolactic fermentation after sun-drying. This study investigated the effects of UV irradiation on the different structural levels of cassava starch as compared to those of corn starch and dextrins. Photosensitive compounds excited at 360 and 290 nm in cassava starch were photodegraded when starch was exposed to sunlight or 360 nm irradiation. UV irradiation depolymerized cassava and corn starches, inducing modifications due, at least in part, to a mechanism involving free radicals. Lactic acid was also photodegraded. Photodegradation induced by UV absorption could have been due to fluorescent chromophores found in starches and nonfluorescent chromophores present in glucosidic units.

Cooking↗
PubMed2001

Detection of irradiated spices by different physical techniques.

We used thermoluminescence, electron spin resonance, and viscosimetric measurements to establish whether or not a spice had been irradiated. Thermoluminescence, using the 1788 EN official protocol with an alternative method for the extraction of mineral impurities, led to proof of irradiation or proof of no treatment. Electron spin resonance led to different spectrum shapes depending on the chemical composition of the spices; ESR could only be used as proof of irradiation up to several weeks after irradiation, and only for some spices. Viscosimetric measurements carried out on spice suspensions led to a presumption of treatment (or of no treatment) and possibly to proof of irradiation.

Electron Spin Resonance Spectroscopy↗
PubMed2000

Identification of irradiation treatment of aromatic herbs, spices and fruits by electron paramagnetic resonance and thermoluminescence.

Electron paramagnetic resonance and thermoluminescence signals induced by gamma irradiation in some herbs, spices and fruits were systematically studied in order to detect the treatment. Using European protocols the validity and effectiveness of these two techniques are compared in regard to time of storage after irradiation.

Electron Spin Resonance Spectroscopy↗
PubMed1998

A point about electron paramagnetic resonance detection of irradiated foodstuffs.

This paper makes a point about the identification of irradiated foodstuffs by means of electron paramagnetic resonance (EPR) or electron spin resonance (ESR). EPR is the most accurate method for such routine applications since radicals are stabilised for a long time in all (or part of) foods that are in solid and dry states; consequently, EPR can be applied to meat and fish bones, fruit and relative products (from vegetal origin). More details are given for mollusc shells, such as oysters and mussels.

Animals↗
PubMed1992

ESR spin trapping analysis of gamma induced radicals in sucrose: II.

Radicals induced by gamma-irradiation of sucrose, in the solid state at different temperatures and in aqueous solution, have been investigated by the spin trapping method. Electron spin resonance (ESR) combined with high performance liquid chromatography (HPLC), followed by spectral analysis with a simulation program (Voyons) revealed seven main radical species. A comparative study of the ESR signals from spin trapped gamma-induced radicals in some glycosides, disaccharides, 13C specifically labelled carbohydrates, as well as in several deoxysucroses and fructans, led to the assignment of a chemical structure to five out of the seven sucrose-nitroxide adducts previously evidenced. Sucrose is shown to be a conceivable model for the study of fructans gamma-radiolysis mechanism in aqueous solution.

Carbohydrate Sequence↗
PubMed1990

E.S.R. spin trapping analysis of gamma induced radicals in sucrose.

Radicals induced by gamma-irradiation in sucrose, in the solid state at different temperatures and in aqueous solution, have been studied by the spin-trapping method. Electron spin resonance (ESR) combined with high performance liquid chromatography (HPLC) then spectra analysis with a simulation program (VOYONS), revealed seven main radical species. Their nitrogen and hydrogen splitting constants were compared with those obtained from fructose and glucose units. Assignments of chemical structures are discussed for three radical species.

Chemical Phenomena↗
PubMed1989

ESR analysis of irradiated frogs' legs and fishes.

Electron spin resonance (ESR) spectral analysis of different parts (bones, scales, jaw, etc.) from ionized (irradiated) frozen frogs' legs and fishes (brown trout and sardine) were recorded. There is always present, after treatment, a signal due to the irradiation. ESR and ENDOR experiments lead us to assign it to h1 centers from hydroxyapatite, as in the case of other irradiated meat bones. The use of ESR to prove whether one of these foods has been irradiated or not is discussed.

Animals↗
PubMedDate not supplied

Identification of irradiated foodstuffs: results of a European test intercomparison.

The results of an intercomparison, organized by the Community Bureau of Reference (Commission of the European Communities), on the use of Electron Spin Resonance spectroscopy for the identification of irradiated food are presented. A qualitative intercomparison was carried out using beef and trout bones, sardine scales, pistachio nut shells, dried grapes and papaya. Protocols are proposed for meat bones, fish bones (with some restrictions) and fruits such as dried grapes and papaya. The protocol for pistachio nuts and fruits such strawberries is more complicated and further research is needed prior the organization of future intercomparisons. A quantitative intercomparison on poultry bones was also organized. Laboratories were able to distinguish between chicken bones irradiated at 1 to 3 kGy or 7 to 10 kGy.

Electron Spin Resonance Spectroscopy↗
PubMedDate not supplied

[Ionizing treatment of food].

After a description of the principles of the radiation treatment of food, the main applications in food industry are listed. Then, the status on possible identification methods for irradiated foodstuffs is described, with a special view on the coordinated action of the Community Bureau of Reference (CEC).

Food Analysis↗