Title: Potential heat treatments for quarantine security of exotic tropical fruits Authors
Submitted to: HortScience
Publication Type: Abstract Only
Publication Acceptance Date: July 18, 2007
Publication Date: July 31, 2007
Citation: Wall, M., P. Follett, and J. Armstrong. 2007. Potential heat treatments for quarantine security of exotic tropical fruits. HortScience 42:982. Technical Abstract: Potential heat treatments (HT) were developed to control fruit flies in selected tropical fruits (avocado, guava, longan, passion fruit, and persimmon). Hawaii has three fruit flies of economic and quarantine importance, Mediterranean fruit fly (Medfly), oriental fruit fly, and melon fly. Previous research showed that Medfly eggs are the most heat tolerant species and life stage among these fruit flies. Initial tests included an approved vapor HT for papaya (raise fruit core temperature to 47.2 °C during 4 h). The 4 h to 47.2 °C HT was effective at controlling Medfly eggs in ‘Fuyu’ persimmon with a very high mortality rate (99.995 %). The same HT was effective in controlling Medfly in guava (100% mortality), but less effective for passion fruit (99.966% mortality). Complete insect kill (100%) was achieved by raising the fruit core temperature in 2 h to 46 °C for passion fruit and to 47 °C for longan, with a 45 min hold time. For ‘Sharwil’ avocado, HT raised the fruit seed temperature in 2 h to 44, 45, or 46 °C with a 30 min hold time. Medfly was controlled at the 46 °C HT (100% mortality), with lower mortality at 45 °C (99.232%) and 44 °C (90.415%). Fruit quality was evaluated for the more promising HT. ‘Fuyu’ persimmon heated to 47.2 °C in 4 h and stored at 1 °C for 7 d, ripened normally and retained good quality. Passion fruit heated to 47.2 °C in 4 h, and stored at 7 °C for 7 d, changed in rind color from bright yellow to golden, but was considered marketable. Avocado fruit quality was unacceptable with the 46 °C HT, but fruit heated to 45 °C were not different from control fruit in quality. Preconditioning avocados at 38 °C for 10 h before HT improved fruit quality slightly, but reduced insect kill.