Abstract
Polyphenol oxidase (PPO) has been shown to be responsible for browning reactions and discolouration in many fruit and vegetable products. Crude polyphenol oxidase (PPO) of ripe and unripe plantain (Musa paradisiaca cultivars – Agbagba, Cardaba and plantain hybrid) was isolated and some of the characteristics of the PPO extracts investigated. The activity of the enzyme was evaluated using spectrophotomeric method. Plantain PPO (ripe and unripe) catalyzes oxidation of both various substrates with catechol being the most readily oxidized substrate. The optimum pH of the enzyme was between pH 6 and 7 for the three cultivars. Thermal inactivation data showed that activity of the enzyme was lost after heating for 15 and 4 min at 50 and 80°C, respectively. Browning reactions of plantain PPO were inhibited by sodium metabisulphite (0.1%), ascorbic acid (0.2%), malic acid (1.0%) and the least sodium chloride (>1.0%) which is similar to banana PPO. Plantain polyphenol oxidase was active towards catechol but not with cresol. Key words: plantain (Musa paradisiaca) cultivars, polyphenol oxidase, catechol, enzyme activity
Highlights
Plantain (Musa paradisiaca) is an important crop in Nigeria as in all humid tropical zones of Africa, Asia, Central and South America (Swennen, 1990)
The activity of polyphenol oxidase (PPO) obtained from unripe plantains was higher than the activity of PPO obtained from ripe plantains
Cathecol was the most readily oxidized by the enzymes. This finding is in line with Sanjeev and Mishra (2011) work that banana PPO is active towards o-diphenolic compounds
Summary
Plantain (Musa paradisiaca) is an important crop in Nigeria as in all humid tropical zones of Africa, Asia, Central and South America (Swennen, 1990). It is grown extensively in the southern states of Nigeria. The flour from ripe fruit has high sugar content which makes it a useful component of infant diet and the carbohydrate have been found to be digested than that of cereal (Ladele et al, 1984). Enzymatic browning occurs in many fruits and vegetables such as when the tissue is bruised, cut or peeled. The objectives of this study are to isolate and determine some properties of enzymes of plantain (M. paradisiaca) cultivars and to evaluate methods of controlling activity of the enzyme
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