Gamma irradiation enhanced flavor volatiles and selected biochemicals in onion (Allium cepa L.) during storage

Gamma irradiation is recommended for inhibition of sprouting in onion during storage. The current study was aimed to understand the effect of gamma irradiation (100 and 200 Gy) on important parameters including flavor metabolites and phenolics of onion bulbs during ambient (26 ± 2 °C, 65 ± 2% RH) storage of 105 d. As analysed using GC/MS, 48 compounds were identified and quantified including aliphatic hydrocarbons, alcohols, esters, aldehydes, furans, and ketones. The organosulfur compounds were the prime odor volatiles (known for pungency) which increased (1.5 fold) in irradiated (200 Gy) onion during storage. The prominent phenolic acids (thirteen nos.) were quantified using GC/MS in onions during storage. Quercetin, the major phenolics in onion increased by more than 25 fold in irradiated and stored onion. The findings showed prominent enhancement of pungency in irradiated onion during storage. The content of pyruvic, ascorbic and phenolic acids including flavonoids and anthocyanins also increased during storage in onion bulbs. The ABTS and DPPH free radical scavenging activity increased by 1.5 and 2 times in irradiated and stored onion, respectively. However, no perceptible change was observed in texture, color, and overall sensory quality of onion bulbs. Unlike major vegetables, current findings showed that most of the quality indicators have enhanced upon storage in onion, which have added advantages.