title: Spatial distribution of total phenolic content, enzymatic activities and browning in white yam (Dioscorea rotundata) tubers.
abstract: Browning in raw and processed yams resulting from enzymes, polyphenol oxidase (PPO) and peroxidase (POD), activities is a major limitation to the industrial utilization of Dioscorea varieties of yams. Two elite cultivars of D. rotundata species were selected to study the spatial distribution of total phenols and enzymes (PPO and POD) activities. The intensities of tissue darkening in fresh yam chips prepared from the tuber sections of cultivars during frozen storage were also studied. Total phenolic content was observed to be highest in the head and mid sections of the cultivars than at the tail end. PPO activity did not have any specific distribution pattern whereas POD activity was found to be more concentrated in the head than in the middle and tail regions. Browning was found to be most intense in the head regions of the two cultivars studied; and was observed to correlate with total phenol and dry matter contents of tubers. Between the two enzymes, POD activity appeared to be more related to browning than PPO.
authors.affiliation: Department of Nutrition and Food Science, University of Ghana, Legon Accra, Ghana.
authors.forename: Seth
authors.initials: S
authors.lastname: Graham-Acquaah
authors.affiliation: Department of Nutrition and Food Science, University of Ghana, Legon Accra, Ghana.
authors.forename: George Sodah
authors.initials: GS
authors.lastname: Ayernor
authors.affiliation: Department of Nutrition and Food Science, University of Ghana, Legon Accra, Ghana.
authors.forename: Betty
authors.initials: B
authors.lastname: Bediako-Amoa
authors.affiliation: Department of Nutrition and Food Science, University of Ghana, Legon Accra, Ghana.
authors.forename: Firibu Kwesi
authors.initials: FK
authors.lastname: Saalia
authors.affiliation: Department of Nutrition and Food Science, University of Ghana, Legon Accra, Ghana.
authors.forename: Emmanuel Ohene
authors.initials: EO
authors.lastname: Afoakwa
keywords: Browning; D. rotunda; Enzyme activity; Peroxidase; Polyphenol oxidase