Comparative identification of irradiated herbs by the methods of electron paramagnetic resonance and thermoluminescence

The influence of gamma-irradiation on the formation of free radicals and antioxidant status of oregano (Origanum vulgare L.)

“…The application of gamma-radiation on oregano samples led to the formation of additional EPR signals -(i) anisotropic triplet (A ⊥ = 0.85 mT, A  = 0.7 mT; g ⊥ = g  = 2.0061; λB pp = 0.67 mT) attributed to carbohydrate radical structures ( Vanhaelewyn et al 2000;Korkmaz & Polat 2001) and (ii) anisotropic triplet (A ⊥ = 3.0 mT, A  = 1.8 mT; g ⊥ = 2.0060, g  = 2.0050; λB pp = 1.2 mT previously attributed to "cellulose" radical species (Yordanov et al 1998;Kispéter et al 2003;Bayram & Delincée 2004;Yordanov & Aleksieva 2004). However, the EPR signal of "cellulose" radical species, which the European Committee for Standardization (CEN) in EN 1787:2000 declared as a marker of gamma-irradiation of natural cellulose-containing materials, is minimal (CEN 2000.…”

Irradiation of spices - a review

“…In 2000, CEN issued the EN 1787 EPR method for the detection of irradiated foods containing cellulose. The gamma radiation treatment of plant products containing cellulose leads to the generation of a typical three-line EPR signal (Yordanov et al 1998Raffi et al 2000), attributable to "cellulosic" radicals. Later, more standardised methods were published for the detection of irradiated foods (i.e.…”

“…EN 1784 and EN 1785 describe methods for the detection of irradiated food containing fat, and EN 1786 a method for the detection of irradiated food containing bone. Unfortunately, their application is limited by the lifetime of the radiolytically produced free radicals (Yordanov et al 1998;Formanek et al 1999;Raffi et al 2000;Yordanov et al 2000;Delincée & Soika 2002;Bayram & Delincée 2004;Suhaj et al 2006;Polovka et al 2006Polovka et al , 2007. Raffi and Stocker (1996) observed that, even though electron spin resonance is known to be a very sensitive method, in the case of spices it did not lead to favourable results because the main radio-induced signal decreased too fast with the storage time and disappeared before the maximal usual commercial storage time.…”

“…For the purpose of post-radiation identification of cellulose containing foods, the presence of relatively weak satellite lines of this "cellulosic" radical species was accepted as an unambiguous evidence for gamma-radiation treatment (Yordanov et al 1998. However, it was observed that the EPR intensity of the "cellulosic" triplet signal gradually decreased with the storage time, and that the rate of disappearance was dependent on temperature, humidity, the presence of oxygen, and other factors (Yordanov et al 1998(Yordanov et al , 2004Bayram & Delincée 2004;Polovka et al , 2007Suhaj et al 2006). In general, the cellulosic EPR signal disappeared within 70 days to 90 days after the irradiation process (Raffi et al 2000).…”

“…In general, the cellulosic EPR signal disappeared within 70 days to 90 days after the irradiation process (Raffi et al 2000). Consequently, the method was deemed to fail in the verification of the gamma-radiation treatment and, consequently, it was recommended that thermoluminescence techniques should be used (Yordanov et al 1998;Raffi et al 2000;Delincée & Soika 2002;Bayram & Delincée 2004). Recently, Yordanov et al (2000) pointed to the different thermal behaviour of EPR signals of non-irradiated and gamma-radiation treated foods containing cellulose, even after a long storage period after radiation, when the specific "cellulosic" EPR signal is extremely low, and recommended this technique as a method to identify gamma-radiation processed foods.…”