1. Vapor heat treatment
Fruit-core temperature is raised with saturated vapor straight from 30 ℃ to 41 ℃ within 45 min. and then up to 46.2 ℃, and treat for 20 min, at 46.2 ℃ or above.
2. Cold treatment
After vapor heat treatment , fruit-core temperature is cooled down to 2 ℃ within 6 hours and treat for 42 hours at 2 ℃