Effect of Ethylene Treatments on Limonin Reduction in Thai Pummelo (Citrus grandis (L.) Osbeck) Fruit

Abstract

Bitterness in the peel and juice of pummelo is mainly caused by limonin. This research studied different preparations of pummelo and used ethylene as fumigant at different concentrations in different treatments—namely, whole fruit (treatment1), pummelo fruit without the fl avedo and albedo (treatment 2), pummelo fruit with only juice vesicle tissue (treatment 3) and pummelo juice (treatment 4). The limonin content in the fl avedo, albedo, juice vesicle tissues and pummelo juice was signifi cantly reduced following ethylene treatment. For effective limonin reduction in juice, the fl avedo and albedo of pummelo fruit must be removed leaving only juice vesicle tissue (treatment 3) before treating with ethylene. The optimum treatment that reduced the limonin content by 78.38% was 200 ppm ethylene and 1.30 hr exposure. Treating pummelo with ethylene had no effect on nomilin, eriocitrin, neoeriocitrin and the antioxidant capacity of the juice; however, ethylene fumigation caused a slight decrease in the naringin content. Treating pummelo juice directly with ethylene had no effect on its limonin content.