(A Peer Review Journal)
e–ISSN: 2408–5162; p–ISSN: 2048–5170


Pages: 596-608
B. C. Obasi, C. M. Z. Whong, S. A. Ado and I. O. Abdullahi

keywords: Baker’s yeast, dough fermentation, mutants, fermented orange juice, wild yeasts


The characterization of the indigenous yeast flora was carried out using analytical profile index techniques (API AUX 20C kit), physiological characterization and genetic modification by mutation (nitrous acid and ultra violet irradiation treatment). The physiological characterization involved the testing of several parameters, which include sugar fermentative ability that is growth of yeast in 50% glucose, 3% and 10% sodium, elevated temperatures of 30, 35, 37 and 42oC. The isolates for dough leavening ability of bread were identified as Kodamaea ohmeri, Candida norvegensis, Candida zeylanoides, Geotrichum capitatum and Rhodotorula minuta. The leavening capacities of wild strains, nitrous acid-induced mutants and the control commercial baker’s yeast ranged from (75-275 ml), (84-275 ml) at 48 h and (98-280 ml) at 180 min and (98-130 ml) at 48 h for the control sample, respectively. Based on the physiological attributes and mutagenicity of the wild yeast strains for dough leavening, the result obtained showed that the mutants of sweetened dough (nitrous acid) had a better leavening capacity than that of the unsweetened dough, while for the ultraviolet irradiated mutants unsweetened dough had a better leavening capacity than that of sweetened dough. However, some species of the wild yeast strains, Kodamaea ohmeri, Candida norvegensis and Rhodotorula minuta had an outstanding dough leavening capacity both in sweetened and unsweetened dough when compared with the commercial baker’s yeast. Thus, this study has enabled the acquisition of data on the basic physiological and mutagenic pattern of yeasts required for industrial production of higher dough leavening capacity with regard to their use in bakery products.


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