Mango fruit aroma volatile production following quarantine hot water treatment and subsequent ripening
Mangos are an important tropical fruit crop worldwide that are appreciated for their attractive peel and flesh colors, juicy texture, sweetness, and unique aroma. Mangos exported to the United States receive quarantine hot water treatment (QHWT) at 46.1 °C for 65 to 110 minutes (depending on fruit shape and size) to prevent fruit fly introduction. However, little is known about changes in fruit aroma following QHWT. Therefore, we examined the aroma volatile production of ‘Tommy Atkins’ mangos after QHWT applied at typical commercial maturity stage (green externally with internal color change initiated) for 0, 70, 90, or 110 minutes. The QHWT duration required by APHIS for the mango fruit in this study is 90 minutes. The fruit were thus treated for the required time plus 20 minutes shorter and longer durations. Following QHWT, fruit aroma volatiles were evaluated within two hours and after four days at 25 °C. Immediately after QHWT, there were much higher levels of acetaldehyde and ethanol as well as slightly higher acetone and methanol in all heat-treated mangos, while β-pinene, ρ-cymene, limonene, 3-carene, and myrcene were higher only after the 70- and 90-minute QHWT. After ripening for four days at 25 °C, few QHWT effects on aroma volatiles persisted. Ethanol was lower in fruit from the 70- and 110-minute QHWT while the 90-minute QHWT ethanol level was the same as the control. Levels of β-pinene, ρ-cymene, and limonene increased during ripening in both control and QHWT. Caryophyllene was inhibited immediately after the 110-min QHWT, but recovered during ripening, while α-copaene, which was almost completely absent initially, was present after ripening only in fruit from the 110-minute QHWT. The results of this research suggest that the QHWT being applied to mangos imported into the United States probably does not significantly affect the aroma of those fruit.