Fruits and vegetables are a major source of fiber, minerals and vitamins,
and different phytochemicals. Fruits and vegetables are consumed as fresh
or processed to different types of safe products with high quality and high
potential health benefits. Naturally present enzymes in fresh fruits and
vegetables are degraded and metabolized after ingestion. They have not
been associated with toxicity and are considered intrinsically safe. But
these enzymes play a major role in the quality of fresh fruits and vegetables.
Enzymes are very important for growth and ripening of fruits and
vegetables and are active after harvesting and during storage. While most
of the enzymes present in plant tissues are important for the maintenance
of metabolism, some have also undesirable effects on color, texture, flavor,
odor, and nutritional value. Activity of lipoxygenase affects flavor and
odor development of some vegetables. Lipase and peroxidase are the other
enzymes causing flavor and odor changes. Phenol oxidases are important
for the discoloration of fruits and vegetables with adverse effects on taste
and nutritional quality. Fruits and vegetables contain pectic substances
that have major effects on the texture. The activity of pectinases causes fruit softening. α-amylases degrade starch to shorter polymeric fragments
known as dextrins and affect the textural integrity. Fruits and vegetables
contain ascorbic acid oxidase, which affects the vitamin availability.