Presence of Carbon-Based Nanostructures in Electron-Beam Irradiated Food Products

Previous studies have shown electron-beam (e-beam) irradiation to be effective in eliminating mold in natural products. More recently, we found the presence of rod-like nanostructures in natural and composite corks following e-beam irradiation. Here, we present an investigation on the effects of e-beam irradiation on wine corks and selected herbs. Chapter 1 reviews the safety of irradiation on food, while briefly covering the health safety of carbon-based nanostructures. Chapter 2 reports the characterization of the nanostructures, herein referred to as nanorods (NRs), found in the commercially irradiated corks, after having been irradiated with 5, 10, and 15 kiloGrays (kGy) from an e-beam. We found larger radiation doses were not necessarily more effective in producing NRs. The characterization of the NRs was carried out by means of energy-dispersive x-ray spectroscopy (EDX), Raman spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Characterization showed dissimilarities between the NRs isolated from irradiated corks and known characteristics of carbon nanotubes (CNTs) used for reference; however, the presence of oxygen (O) in the NR structure suggests a different nanostructure possibly not previously identified. Chapter 3 demonstrates similar nanostructure formation from e-beam irradiation on the selected herbs and spices: basil, cilantro, oregano, parsley, and flour. The herbs and spices were irradiated with 1, 3, and 5 kGy. Similar to the case of e-beam irradiation of corks, larger radiation doses did not necessarily produce more nanostructures. Finally in Chapter 4, conclusions, perspectives, and future work based on Chapter 2 and 3 are presented.