Effects of Hot Water Treatment and Storage Temperature on Internal Quality and Volatile Compounds of Grapefruit

Fruit decay and chilling injury are two major causes for grapefruit quality losses during postharvest handling, transportation, and marketing. ‘Marsh’ white grapefruit were harvested in March or September 2015 and then dipped in heated (53^oC) or ambient (25^oC) solutions for 120 seconds before storage at optimum (10°C) or chilling (5°C) temperatures. Fruit chilling injury, decay, internal quality and volatile compounds were determined after 7 weeks storage and 7 weeks plus 1 week at room temperature (storage +1 week). Chilling injury of fruit harvested in March 2015 was reduced 48% by hot water treatments compared to the control after 5°C storage +1 week, and chilling injury was also reduced 46% by hot water treatments when fruit were harvested in September 2015. In spring 2015, fruit dipped in hot water also developed 56% or 75% less decay than the control during storage at 5 or 10°C, respectively. For fruit harvested in March 2015, the hot water treatment enhanced fruit Brix by 8.7% without affecting weight loss. This effect was perceived by a 55-member untrained taste panel, which preferred heat-treated fruit and perceived them as sweeter compared to the control after storage +1 week. In fall 2015, hot water treated fruit tended to have 1.2% higher Brix than the control, but this was not significantly different. Compared to fruit stored at 10°C, fruit acetaldehyde content increased while ethyl acetate declined during storage at 5°C. After treated with hot water, fruit stored at 5°C had similar acetaldehyde and ethyl acetate content as fruit stored at 10°C. The use of hot water dips could be used to improve postharvest quality of Florida grapefruit.