Question
Cut surfaces of fruit and vegetables often become dark because
dirty knife makes it dark
oxidation of tannic acid in the presence of trace of iron from the knife makes it dark
dust of the air makes it dark
none of the above.
Solution
B.
oxidation of tannic acid in the presence of trace of iron from the knife makes it dark
When fresh fruits and vegetables are peeled or cut open, the enzyme called polyphenol oxidase (also called tyrosinase) contained in the cells is exposed to and reacts with the oxygen in the air. The reaction that occurs, which is called oxidation, is what turns the fruits and vegetables brown.
