Friday, August 31, 2012

Why do ripened mangos have a strong smell?
BINDITA SHRIMALI (She is a member of IAS OUR example for all members to remain motivated and evn ull can send questions to HINDU to address INQUISITIVENESS)

The fruit ripening signal is the sudden production of ethylene. Ethylene is the simple hydrocarbon gas produced in the ripening fruit and released into the atmosphere. This ethylene signal causes developmental changes that result in fruit ripening. These developmental changes are triggered by the set of enzymes called hydrolases. Ethylene apparently ‘turns on’ the genes that are transcribed and translated to make these enzymes. The enzymes then catalyze reactions to alter the characteristics of the fruit.
The action of the enzymes causes the ripening responses. Chlorophyll is broken down and sometimes new pigments are made so that the fruit skin changes color to red, yellow, or blue. Acids are broken down so that the fruit changes from sour to neutral.

The starch is digested by amylase to produce the simple sweet sugars. As a result, the mealy quality is reduced and juiciness is increased. Finally enzymes break down large organic molecules into smaller ones that can be volatile (evaporate into the air), which we can detect as an aroma. A wide range of such compounds has been identified, including esters, lactones, mono- and sesquiterpenes. Monoterpene hydrocarbons such as cis-ocimene, alpha and beta-pinene, myrcene and limonene seem to be particularly important contributors to the flavor of the fresh fruit, depending upon the variety. 

The momoterpene cis-ocimene is a major flavor component in mango cultivars Alphonso from India and Jaffna from Srilanka, Among the sesquiterpenes, beta-caryophyllene and alpha-humelene are common components in the volatiles mixture of almost all cultivars of mango.

The mango fruits are harvested in any one of the three stages namely mature green stage in which the fruits have pale ash green colour with smoky appearance, half-ripe stage and ripe stage. The pulp of ripe fruit harvested at the mature green stage exhibited higher total amounts of the aroma volatiles namely the monoterpenes and the sesquiterpenes. Fruit harvested at the fully ripe stage resulted in higher concentrations of esters, alkanes and norisoprenoids. To achieve better quality and greater aroma volatile production of the ripe fruit, mango should be harvested at the mature green stage.
Editor, Research Journal of Biological Sciences
J.J. College of Arts and Science
Pudukkottai, Tamil Nadu


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