Most fruit first become ripened because of the release of a hormone within the fruit and the plant called ethylene (H2C=CH2). Ethylene causes the breakdown which in itself causes a production of enzymes that break down the structures of the fruit (eg.: amylase, pictenase).The eyhylene gas also destroys the green pigment of the fruit chlorophyll. But for any fruit to become ripened there needs to be a high enough concentration of ethylene around the fruit to even begin to ripen.
The process of the fruit spoiling is just the decomposition of the fruit itself. That is mostly caused by the the two enzymes previously mentioned - amylase and pectinase. The role that these enzymes play are like biological scissors. The structure of plants are made out of carbohydrates - mostly starches.
The amylase acts on the starches, which are made of amylose, which is just a long chain of glucose molecule. And what the amylase does is it cuts the bonds of the starch chain, so then the glucose molecules are free; and now the fruit tastes sweet.
The other enzyme pectinase does almost the exact same thing as amylase, it cuts away the bonds of the pectin molecule so now we have a bunch of pectinic acid, and now the fruit is soft enough to eat. Pectin is extremely important for a fruits/plants because it hold the cells together.
Fruits become discolored due to chemical reactions as well. Like previously stated before, ethylene destroys chlorophyll. When most fruits are produced, they all initially contain chlorophyll. Fruits then become ripened due to other chemicals within the fruit and as well as chemicals outside of the fruit.
And what I would hypothesize that the effect of sunlight would have on the ripening of fruit would be that it would increase the ripening process. There would be increase kinetic energy, thus an increase in of effusion of ethylene gas and as well as increase of of activation energy to start the chemical reactions. I would also guess that too much energy would cause the cells to rupture as well.
I would also hypothesize that the UV radiation would have the same effects as it does in every living cell. The UV radiation would heat the DNA and causes a release of enzymes called DNAses that cut away at DNA and destroy the DNA. Staying with that same idea, the UV light would also endanger synthesis of enzymes and proteins that the cells would need for proper cell function, leading to a faster decomposition of the fruit.
I hope this helps.
· 1 decade ago