Ripening is a dramatic event in the physiology of a fruit. It is visualised by monitoring changes in color, smell and texture of the fruit. Among these, change in texture is an important aspect as it has a great impact on the life of the fruit. Textural changes are effected by various pectolytic enzymes, each one having a characteristic role in individual fruits. The pectinesterases have been intensively studied in almost all fruits and vegetables. The polygalacturonases have been relatively less studied. Hence, the book emphasises on the presence and role of polygalacturonase in fruit ripening. It is hoped that the information contained herein will provide - insights to biochemists, especially protein biologists, vital information to biotechnologists specializing in molecular biology and even food technologists.