Identification of freeze damage in oranges using gas sensor

Abstract

Three volatile sensing systems and two sampling methods were evaluated to determinetheir ability to detect freeze damage in Valencia oranges (Citrus sinensis (L.) Osbeck Valencia) 24hours after laboratory-simulated freezing. Carbon dioxide and ethanol were measured usinghandheld gas sensors and an electronic nose was employed to measure the overall gas profile ofeach orange. For carbon dioxide, optimal classification was obtained using internal gas samplingwith a classification accuracy of 87% and 47% for unfrozen and partially frozen Valencia oranges.Discrimination using ethanol was optimal using headspace gas sampling and correctly classified100% of sound fruit but only 40% of the partially frozen fruit. In general, sensing of the overallvolatile composition using an electronic nose resulted in a more balanced classification than bysensing individual components such as carbon dioxide and ethanol. The electronic nose correctlyclassified approximately 73% and 74% of sound fruit and 70% and 67% of the partially frozen fruitwith headspace and internal gas sampling methods respectively.