How can an unriped fruits turn to ripe even when they are off the trees?

Question

fruits like mango watermelon melon and banana sometimes are picked unripe and shall be waited till it is riped off the their strees.how does that happen?

Answer 1

Ripening is a process in fruits that causes them to become more edible. In general, a fruit becomes sweeter, less green, and softer as it ripens. However the acidity as well as sweetness rises during ripening, but the fruit still tastes sweeter regardless. The reason for this is the Brix-Acid Ratio.

The life stages of a plant are influenced by plant hormones. An organic compound involved with ripening is ethylene, a gas created by plants from the amino acid methionine. Ethylene increases the intracellular levels of certain enzymes in fruit and fresh-cut products, which include:

Amylase, which hydrolyzes starch to produce simple sugars, and

Pectinase, which hydrolyzes pectin, a substance that keeps fruit hard.

Other enzymes break down the green pigment chlorophyll, which is replaced by blue, yellow, or red pigments.

Hormone levels in fruit are often connected to pollination. If too few seeds in a multiseeded fruit are formed (by fertilization of the ovules), the flesh of the fruit may not develop in some areas, and as a consequence ripening will be retarded or prevented. Fruit growers increasingly monitor seed ratios in developing and/or mature fruit and adjust pollination management accordingly.

Many fruits are picked prior to full ripening because ripened fruits do not ship well. For example, bananas are picked when green and artificially ripened after shipment by being gassed with ethylene. A similar method used in parts of Asia was to cover a bed of slightly green-harvested mango and a few small open containers of clumps of calcium carbide with a plastic covering. The moisture in the air reacted with the calcium carbide to release the gas acetylene, which apparently has the same effect as ethylene.

In essence fruits contain ripening compounds and hormones even when they are picked early (unless they are picked extremely early before the fruit has had time to mature properly.) They are picked early to avoid damage to the fruit and to increse shelf life. They can be artificially ripened when needed, they will still ripen naturally, but this enables, shops etc to control the ripening a little more.

Answer 2

The picked fruit is still alive. It is carrying the seeds of the new generation. Enzymes within the fruit cause the changes of ripening. Essentially the fruit is the protective vehicle and food for the seeds.

Answer 3

Conversion of unripe fruits to ripe fruits is a phenomenon which involves a series of enzymatic actions.  These enzymes get triggered when the seeds are about to mature.  This signal starts this reaction and the fruits starts ripening. There are number of events such as (i) change in the skin colour of the fruit i.e. green to yellow (mango), green to purple ( jambhul), green to creamish green (custard apple), green to red (apple), (ii) change in the taste of the pulp sour to sweet, (iii) change in the texture of the fruit pulp hard to soft. The enzymes responsible for  all these changes are present in the cells of the fruit.  Therefore even though  the fruit is plucked from the tree it can show all these changes. These enzymatic changes require a certain temperature ( approx. 35 degrees C.). Then these changes are accelerated and the fruits ripe quickly.

Answer 4

very simply put the cells have not yet died so they continue to mature using what resources they have in the fruit. Gases put off by other decaying fruits will speed the process up.