Screening and identification of electron-beam irradiated dried spice-mixture products by electronic sensing and standard analytical methods through dose estimation

Abstract

Spice is a highly susceptible to microbial contamination and its microbial decontamination by irradiation has been increasing worldwide now. Therefore, a reliable detection method for irradiated food is required in compliance with existing labeling regulations. Two different commercial spice-mixtures samples (A and B) were subjected to electron beam (E-beam) irradiation at 0–14 kGy, for which four different analytical approaches were employed: photostimulated luminescence (PSL), electronic nose (E-nose), electron spin resonance (ESR) spectroscopy, and fourier transform infrared (FTIR) spectroscopy. As screening trials, PSL analysis revealed negative results from non-irradiated samples (sample A) (<700 photon counts/60 s: PCs), while positive results from irradiated samples (>5000 PCs/60 s). E-nose approach through principal component analysis also showed a clear discrimination in their flavor patterns between non-irradiated and irradiated samples. The above screening results were effectively validated through determination of radiation-induced crystalline sugar signals by ESR spectroscopy. However, FTIR spectra showed that no significant alterations were observed in functional groups of spice samples upon irradiation. These trials of detection for unknown spice mixtures demonstrated that sample B was found to be irradiated without any labelling on commercial product packages in markets, that was assured through standard PSL and ESR analyses.