Identification of X-ray irradiated walnuts by ESR spectroscopy

An inter-laboratory comparison to evaluate the suitability of EN 1787 standard to detect irradiation in plant-origin foods with health benefits

“…No false positive results were obtained with hazelnuts and walnuts, which indicated that the nuts had not been bleached. As expected and recently reported for hazelnuts and walnuts by Chiappinelli et al (2019) and Tomaiuolo et al (2018), the intensity of the satellite lines decreased with time (Fig. 7), but they were still visible for a long time (two years Bortolin, et al Food Control 117 (2020) 107326 after irradiation and more).…”

“…Fig. 8. b shows an evident decrease also of the central peak which supports the presence in that structure of not stable radiation-induced signals already reported in literature and, in particular, of a central line belonging to the same structure of the satellite lines, as confirmed by Chiappinelli et al (2019) and Tomaiuolo et al (2018). Peanuts provided slightly different results; 2 out of 15 samples were Bortolin, et al Food Control 117 (2020) 107326 not correctly identified and the fading was faster (Fig.…”

“…It uses the Electron Spin Resonance (ESR) technique to identify the radical induced in cellulose by ionising radiation; this radical yields an ESR spectrum characterised by two weak satellite lines at a specific distance (about 6.0 mT) from each other and symmetrically located on the sides of an intense peak detectable in untreated samples as well. The central peak, whose intensity strongly increases after irradiation, is indeed the results of the superposition of different signals including the central component of the two satellite lines (Bortolin, Bustos Griffin, Cruz-Zaragoza, De Coste, & Onori, 2006;Chiappinelli et al, 2019;Franco et al, 2004;Tomaiuolo et al, 2018). The application of the https://doi.org/10.1016/j.foodcont.2020.107326 Received 24 December 2019; Received in revised form 17 April 2020; Accepted 27 April 2020 method is simple and time-saving: no laborious sample preparation is required and the measurement usually takes a few minutes.…”

“…In addition, once validated the method does not require confirmation of the nonnegative results. The method has been internationally validated through trials for pistachio nut shells, strawberries and paprika (Linke et al, 1995;Linke et al, 1996;Raffi, 1992;Raffi, Stevenson, Kent, Thiery, & Belliardo, 1992;Schreiber et al, 1993;Schreiber et al, 1996) but, in principle, it could be applicable to all vegetables containing cellulose (Chiappinelli et al, 2019;Jeong, Akram, Ahn, & Kwon, 2014;Jo, Kyung, Park, & Kwon, 2016;Maghraby, Salama, Sami, Mansour, & El Sayed, 2014;Raffi et al, 1989;Sezer, Ece, Uslu, Osmen, & Savin, 2019;Shahbaz, Akram, Ahn, & Kwon, 2013;Tomaiuolo et al, 2018). In practice, however, its reliability in detecting irradiation is limited when the sample has a low content of crystalline cellulose and/or a high moisture content, which favours radical recombination leading to false negative results (Bortolin, Bustos Griffin, Cruz-Zaragoza, De Coste, & Onori, 2006;Kwon, Ahn, Akram, Son, & Lee, 2013;Yordanov, Lagunov, & Dimov, 2009).…”

An analysis of cellulose‐ and dextrose‐based radicals in sweet potatoes as irradiation markers

“…The maximum allowed irradiation dose varies based on product type, expected purpose, and anticipated shelf life. Irradiation doses used for insect disinfestation (e.g., in dried fruits) are typically less than 1 kGy, while irradiation doses used for pest control (e.g., in papayas) and spoilage microorganisms control (e.g., E.coli in ground beef) are between 1 to 10 kGy, and 4.5 to 7 kGy (refrigerated and frozen) (Miller, 2005;Tomaiuolo et al, 2018). The maximum irradiation dose allowed for animal foods (up to 50 kGy) is higher than human foods (up to 30 kGy, except the special cases like sterilization of foods used solely in the National Aeronautics and Space Administration (NASA) space flight programs, which might go up to 100 kGy) (FDA, 2001(FDA, , 2015.…”