Physical and Chemical Composition of Storage-Ripened Papaya (Carica papaya L.) Fruits of Eastern Tanzania

The proximate composition (ash, titratable acidity, crude fat, crude fibre, moisture and sugars), soluble solids, ascorbic acid, polyphenol oxidase activity, macro-nutrients and heavy metal contents of storage-ripened papaya (Carica papaya L.) fruits from Mbezi, Dar es Salaam, Tanzania were determined. The determinations were repeated for early, middle and late-season papaya fruits. The fruits were always harvested at the mature green stage and allowed to ripen during room temperature storage. The results showed that papaya fruits had high moisture content (>85.5%), low acidity (<0.18% c.a.), low crude fat (0.10 g/100 g-edible portion), moderate crude fibre (1.45 g/100 g-edible portion), high ascorbic acid content (>84.5 mg/100 g- fw), moderate total sugars (>13.0%) and soluble solids (>12.9%) content. Early-season fruits had the highest polyphenol oxidase (PPO) activity while late-season fruits had the lowest PPO activity. During storage-ripening the PPO activity in the papaya fruit decreased. Of the determined macro-nutrients (Ca, K, Mg, Na), potassium content (420 mg/100 g-fw) was the highest. Heavy metals content was very low in the papaya fruits. Variations in moisture content, reducing sugars, total sugars, soluble solids, titratable acidity, ascorbic acid content and PPO activity were observed during the season and during the ripening period.