Lately, use of chemicals to artificially ripen fruits is in full swing. Firstly, how do they do it? Next, Are there any ways to distinguish between those that are naturally ripened and those that are artificially ripened?
Technically, there is no difference between naturally ripened fruit and artificially ripened fruit... they're both ripened fruit. I suppose you were looking for some sort of simple chemical test to distinguish between them; but like I said, there's no point in it since in both cases you end up with ripe fruit.
Fruits normally emit ethene (ethylene) which is essential to the ripening process. Which is why fruits picked before they're ripe are sometimes wrapped in a bag that seals in whatever little ethene they emit, thereby accelerating the ripening process.
As you would know, calcium carbide does not ripen fruit per se. Rather, it is the reaction of calcium carbide with water/moisture to release ethyne (acetylene) that's important here. Though I do not know of their mode(s) of action, apparently ethyne is almost a effective as ethylene in ripening fruits (I still need to find a reliable reference for this; though it is supposed to be a fairly well known fact).
If you let a fruit ripen naturally, or if you use ethyne instead... there's really no chemical difference at the end (apart from the usual arsenic contaminants that's associated with commercial-grade calcium-carbide).
The actual mechanism by which ethene (ethylene) and ethyne (acetylene) initiate, and thereafter, accelerate fruit-ripening is not really understood. Pectinases play a major role in the ripening process (they break down a structural component of plant cell walls called "pectin", which is why ripe fruit tend to be soft), however the scientific community has not yet arrived at a consensus as to how ethene and ethyne are linked to the activation/production of these enzymes.
However, there are a couple of subtle (non-chemical) difference between naturally and artificially ripened fruit:
Fruit that has ripened prior to plucking tend to be "fuller" than artificially ripened ones. This is because the fruit still gets an influx of nutrients while it's still attached to the tree...in other words; in the time it takes to ripen, the fruit grows as well. Artificially ripened fruit however, tend to be smaller, as they pretty much stop growing as they ripen (off the tree). ["Small", "big", "fuller" are crudely defined terms...you need some "experience" with fruits if you want to put this tip to good use].
Additionally, if you find the fruit being sold off-season (i.e- At a time of the year when it doesn't usually grow/ripen), for a normal or somewhat cheaper price...then in all likelihood you have an artificially ripened fruit in your hand.
It doesn't matter how it was ripened. It's ripe, that's all there is to it (from a consumer's PoV). Don't forget to wash and peel it before taking a bite :-)
Ethylene (C2H4) triggers enzymes including kinase (neutralizes acid), amylase (converts starch to sugar), hydrolase (degrades chlorophyll) and others to start ripening fruit. Calcium carbide, when in contact with moisture (such as on the surface of the fruit) produces acetylene (C2H2) which is quite similar to ethylene in starting ripening. For more information, visit Wikipedia.
One of the most simple tests include putting the mangoes in a bucket of water . The naturally ripened mangoes will sink while those that are artificially ripened would float. (because the density of artificially ripened would be lower than those that are naturally ripened.
And the color of the mangoes also indicate their ripening process . In some places there would be patches of green.
And I have also experienced burning taste while eating
And after we cut these mangoes certain places would be very ripe and other areas would still be hard(somewhat).
For more information click link https://www.youtube.com/watch?v=cwk-rtHPdes&t=42s