Degradation of monoterpenes in orange juice by gamma radiation

Single-strength orange juice was irradiated with 0, 0.89, 2.24, 4.23, and 8 .71 gGy of gamma radiation at 5 degreesC and then stored at 7 degreesC for 21 days. Volatile compounds, isolated by solid-phase microextraction, were separated and identified using a gas chromatograph equipped with a mass sel ective detector. The majority of the volatile compounds were terpenes, and the most abundant volatile compounds were ethanol and limonene. Most volati le compounds were stable during the 21-day storage period except geranial a nd neral which decreased over time. Irradiation reduced the concentration o f acyclic monoterpenes, such as geranial, neral, myrcene, and linalool 1 an d 7 days after irradiation, but did not affect other monoterpenes, sesquite rpenes, or other Volatile compounds. The reduction of acyclic monterpenes i ncreased linearly with radiation dose, and correlated with an increase in t hiobarbituric acid reactive substrates (TBARS) content. Reduction in the co ncentration of monoterpenes induced by irradiation was not significant 21 d ays after irradiation. Our results indicate that acyclic monoterpenes are s ensitive to irradiation whereas most other volatile compounds are resistant .