When you cut apple and leave it a few minutes in the fresh air, the white juicy meat of apple turns brown. Nevertheless, the fruit is edible, but still somewhat unsightly, especially if you serve to the guests. Check why this reaction occurs and how it can be prevented!
Apple is one of the most accessible and the healthiest fruit. It is an excellent source of energy and active substances; it helps to improve the resistance of the body and plays a major role in preventing many diseases. In this period apple is almost in every home in abundance, so we can often afford it.
But regardless of whether we reach to acidic, sweetness, green, yellow or reddish apples, it always appear the same ‘problem’, namely, when an apple is cut or bite, the pulp soon turns brown. If we immediately eat the fruit, browning is not so pronounced, the greater problem arises when we cut an apple and leave it for a while in the air. Well, there is nothing wrong or apple is no less edible and although it is primarily an aesthetic problem, everyone likes fresh and juicy fruit with no brown spots.
Why an apple turns brown?
Therefore, if an apple is cut into wedges, and we want to eat after some time, we see that soon the white pulp tanned which is especially pronounced if the fruit peeled. Have you ever wondered why? It’s no secret that the ‘guilty’ is oxidation. Apple does contain substances called Polyphenols, which, protect our body against free radicals and oxidative stress, and are basically antioxidants.
So when white apple meat, rich in antioxidants, is exposed to oxygen in the air which is an oxidizer, chemical reaction occurs, a process that allow the enzyme Polyphenol oxidase, which is also located in the apple. The reaction is the brown-colored polymers, which some call it melanin although the chemical structure is not the same as that melanin from human skin.
How can we prevent browning of an apple?
As mentioned above, the sliced apples, which are already tanned, edible, but might look a bit unattractive especially if we intend to serve to the guests. Browning can be prevented in many ways; in particular, we must prevent access to oxygen or to stop the functioning of enzymes. Surely you’ve heard that already helps, if sliced apples are immersed in water, as we prevent the access of oxygen.
A very effective in inhibiting the effects of enzymes, is the ascorbic acid or vitamin C, which is located for example in the lemon juice and other citrus fruits. So when the fruit is cut, we drizzles with lemon or orange juice. Similarly works well, acetic acid, but is not the most suitable because of the sharp smell.
The color of apple flesh can be sustained also by cooking, for example, so that the fruit slices are short-term immersed in boiling water. Enzymes are proteins and therefore also Polyphenol oxidase is sensitive to an elevated temperature; at a temperature above 70 ° C, is changed to an extent they can no longer catalyze oxidation of Polyphenols.
Of course, there are several ways of preventing the browning of apples, but in everyday life are more or less useless. Apples, for example, can be cut in a container filled with pure nitrogen, and will not brown.