Polyphenoloxidase and Perioxidase Activity During Open Air Ripening Storage of Pineapple (Ananas comosus L.), Mango (Mangifera indica) and Papaya (Carica papaya) Fruits Grown in Dar es Salaam, Tanzania

Abstract

Polyphenoloxidase (PPO) and perioxidase (POD), the enzymes responsible for causing browning and change in texture and flavor of fruits and vegetables, were extracted and measured in harvested mature pineapple (Ananas comosus L.), mango (Mangifera indica) (Viringe and Dodo varieties) and papaya (Carica papaya) fruits during off vine, open air, room temperature ripening storage. The initial (at harvest) average PPO activity values in Δ Optical Density (OD) per minute per cm³ of enzyme solution were 0.00074, 0.00083 and 0.0010 for early, mid and late season pineapple fruits respectively. The initial average PPO activity values in ΔOD/min/ cm³ of enzyme solution were 0.00152, 0.00121 and 0.0010 for early, mid and late season ‘Viringe’ mango fruits, respectively and 0.0054, 0.0041 and 0.0024 for early, mid and late season ‘Dodo’ mangoes. For papaya fruits, early, mid and late season fruits had initial average PPO activities of 0.00252, 0.00143 and 0.00085 Δ OD/min/cm³, respectively. The PPO activity decreased continuously during the open air ripening storage of all the fruits while the POD activity increased during ripening storage. Variations in PPO and POD enzyme activity were observed across the season and during the ripening period.