Fermentation

In fermentation, certain substances in food undergo chemical changes which affects its flavour, odour and texture. Fermentation is carried out by micro organisms under special conditions. The process is often combined with salting. Fruits and vegetables are preserved by this process.

   In addition, food substances that contain poisonous ingredients are first subjected to fermentation so as to improve the poisonous substance before preservation. For example cassava is a staple food in west Africa where it is produced in large quantities. Cassava contains a poisonous substance called cyanide. This dangerous substance is removed by fermentation for three to four days. Drying and smoking methods are then applied for preservation of the cassava.

   Fermentation has alcohol , carbon dioxide and  small energy as bye products. In palm wine fermentation produces alcohol which helps to preserve palm wine from bacterial infection.

   Furthermore, tobacco and tea leaves are preserved by fermentation through curring.