Journal of Pure and Applied MicrobiologyVol. 2 No. 1

Some Properties of Two Forms of Yeast Isolated from Naturally Fermented Pawpaw (Carica papaya)

B. Boboye*, K. Adeyemi and O.L. Jimoh

Department of Microbiology, Federal University of Technology, P. M. B. 704, Akure, Ondo State (Nigeria).

Received on January 19, 2008; and accepted on February 25, 2008

 

ABSTRACT

Carica papaya (pawpaw) was naturally fermented for 14 days at the room temperature range of 27oC to 31oC. The pH of the pawpaw changed from 3.73 to 3.01. During the fermentation, ‘Bol 1’ (Oval) and ‘Bol 2’ (elongated) forms of yeast were isolated and their properties namely: fermentation of carbohydrates, formation of pseudomycelium and spore, reduction of nitrate, optimum growth temperature and qualities of bread loaves made with the isolates were determined. The ‘Bol 1’ yeast fermented more carbohydrates faster than the elongated one. It fermented glucose, fructose, sucrose, mannose, trehalose, galactose, maltose and cellobiose but assimilated arabinose and lactose. The ‘Bol 2’ isolate could breakdown the carbohydrates with the exception of galactose, arabinose, lactose, trehalose and cellobiose. The two yeasts did not form spore nor pseudomycelium neither reduce nitrate. They grew optimally at 37oC. Relative best quality bread loaves were obtained with mixture of the two yeasts followed by the ‘Bol 1’ isolate, then commercial yeast (Fermipan or Saf-instant) and ‘Bol 2’ type with total scores of 82%, 80%, 72% and 51% respectively. Also, the mix isolates produced higher amount of alcohol from pawpaw than the 'Bol 1' while the 'Bol 2' yeast synthesized the least quantity.

Keywords : Carica papaya (Pawpaw), yeasts, fermentation.