E-sensing, calibrated PSL, and improved ESR techniques discriminate irradiated fresh grapefruits and lemons.

Abstract

Grapefruit and lemon were exposed to phytosanitary irradiation doses of 0, 0.4, and 1kGy, and then electronic-sensing screening of irradiation status and identification of radiation-induced ESR markers were conducted during 20days storage. Codex standard photostimulated luminescence measurement (PSL1) was not a reliable indicator of irradiation status. Electronic tongue and electronic nose, however, showed potential as screening tools for discriminating irradiated fruits from non-irradiated counterparts based on principal component analysis of taste attributes and flavor patterns. Calibrated PSL approach clearly distinguished irradiated from non-irradiated samples based on the PSL ratio (PSL2/PSL1). Verification of irradiation status by electron spin resonance spectroscopy revealed clear paramagnetic centers from both irradiated fruits samples and ethanol-vacuum drying pretreatment improved radiation-induced ESR signal detection; not prominent enough in 0.4kGy-irradiated commodities during 20days of storage. Peel parts of both fruits showed high limonene which proportionally increased with irradiation doses (p < 0.05kGy).