I heard about dipping mangoes in hot water bath when I was in college. They are saying it’s a quality control measure. the other details are vague.
Time to clear the vagueness by mean of two sources. Hot Water Dipping is done for two reasons.
From fao.org. Done to mango and pawpaw to prevent latent Anthracnose development. There are two methods of implementation.
a) Fruits are dip in hot water, 55ºC, for five minutes. Placing in cold storage immediately is refrained to prevented fruit injury.
b) Fruits are dip in hot water, 55ºC, with 0.1% Benomyl(Benlate) for 1 to 3 minutes.
The two processes are done with strict monitoring. Slight deviation from specified time and temperature might be detrimental.
From bar.gov.ph. In years 2002 and 2006, mangoes exported to China were intercepted due to insect larvae. Because of two separate incident, all mangoes exported to China are required to undergo expensive vapor heat treatment.
The second reason is to eradicate all insects.
Researchers from PHTRC-UPLB, Postharvest Horticulture Training and Research and Philippine Nuclear Research Institute, PNRI, developed the EHWD as much cheaper alternative.
EHWD – extended hot water dipping entails dipping mangoes in hot water, 47 to 48ºC, until the pulp temperature reaches 46ºC, maintained for 15 minutes, then 10 minutes air cooling and 30 minutes tap water cooling. Fruits are then air dried before packing. It is applied 48 hours after harvest on mature fruits to prevent internal breakdown. It has no effect on ripening, quality and sensory properties.
Other important requirements of EHWD
1) Mature mangoes, immature tend to undergo internal breakdown.
2) Insect proof treatment facility
3) Accurate timers and heat sensors
4) Carton with netted vent holes to prevent re-infestation.
5) BPI quarantine officer to monitor the procedure.