Changes in Volatile Flavor Components of On-shelf Ponkan Juice Resulting from Ultraviolet A Irradiation
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Abstract:
Herein, the effects of ultraviolet A (UVA) irradiation on the flavor proprieties of on-shelf not-from-concentrate (NFC) Ponkan juice were evaluated and compared with those under dark storage. Polyethylene terephthalate-bottled NFC Ponkan juice was stored at 25 ℃ and subjected to UVA irradiation for 30 days. Bottles of Ponkan juice stored in the dark were used as controls. Volatile compound composition and contents of Ponkan juice were analyzed by headspace solid-phase microextraction with gas chromatography-mass spectrometry/pulsed flame photometric detection at day 0 and 30 days after storage in the dark or exposure to UVA. The odor active value (OAV) was used to screen flavor components significantly affected by the UVA irradiation, and the overall flavor of the on-shelf juice was evaluated. Overall, 43, 51 and 53 volatile compounds were detected in juice samples collected on day 0, day 30 after storage in the dark, and day 30 after UVA exposure, respectively. Among the components showing significant concentration differences after dark storage and UVA irradiation, a total of 22 key flavor components with OAV≥1 were identified, which included six alcohols (such as linalool), six aldehydes (such as phenylacetaldehyde), four hydrocarbons, three volatile sulfur compounds (such as dimethyl sulfide), two esters, and one ketone. Moreover, the odor intensities (in terms of OAVs) of floral flavor components from the three samples were as follow: day 0 (583)> day 30 in the dark (456)> day 30 of UVA irradiation (400), whereas those of off-flavor components showed the opposite order (83, 135, and 284, respectively). Sensory evaluation further verified the detected changes in the odor attributes of on-shelf juice, including enhanced dimethyl sulfide production rate upon UVA exposure. In conclusion, UVA irradiation speeds up flavor deterioration of Ponkan juice by modifying the compositions and concentrations of flavor components.
