Basically, ripening is a process which makes the fruit sweeter and tastier by involving a variety of metabolic process. It may be considered as a special case of senescence. In this process, a number of enzyme related reactions takes place inside fruits such as hydrolysis, change in pigmentation, respiration rate etc. These processor changes are caused by a ripening hormone.
It has been noticed that the production of ethylene goes up in the ripening process. The ethylene production in some fruits like mango responds when the fruit is harvested although the ethylene may be present before ripening also. In banana, this ethylene production remains ineffective at the early stage even though it is present in the fruit. It becomes effective only when the fruit matures and begins to ripe.
So, this ethylene mechanism ad breaking of insensitivity of ethylene is acquired only when fruits reach their maturity stage.
In case, if a fruit is kept inside rice tin then the time in which a fruit matures is shortened. This may be because when a fruit is kept inside rice tin, the fruit is cut off from the lightening which promotes yellowing. In this case, the ethylene which is produced diffuses rapidly through the fruit’s tissues.
So, the reason that raw fruits like mango ripe faster when kept in rice tin is because the ethylene’s flow is restricted and it forms a layer around the fruit which accelerates ripening and if the same fruit is placed in the air, this ethylene is lost in the air and the fruits are not able to ripe.