Production and characterization of volatile compounds and phytase from potentially probiotic yeasts isolated from traditional fermented cereal foods in Nigeria.

Background: Probiotic strains are incorporated into food substrates to contribute to fermentation process. The
technological suitability of such strains to improve the flavor and nutritional value of fermented food is strainspecific. Potentially probiotic yeasts isolated from Nigerian traditional fermented foods were assessed for production
of volatile compounds by gas chromatography-mass spectrophotometry. Phytases were characterized for activity
and stability at different pH (3–8) and temperatures (25-50 °C).
Results: A total of 45 volatiles compounds were identified from intracellular cell-free extracts of Pichia kluyveri
LKC17, Issatchenkia orientalis OSL11, P. kudriavzevii OG32, P. kudriavzevii ROM11, and Candida tropicalis BOM21. They
include alcohols (14), carbonyls (13), esters (10), and organic acids (8). Phenylethyl alcohol was the highest higheralcohol in Issatchenkia orientalis OSL11 (27.51 %). The largest proportion of esters was detected in P. kudriavzevii
OG32 (17.38 %). Pichia kudriavzevii OG32 and C. tropicalis BOM21 showed vigorous gowth in minimal medium
supplemented with sodium phytate (2 g L−1
). Extracellular phytases from P. kudriavzevii OG32 and Candida tropicalis
BOM2 showed optimal activiy at pH 4.6 (104.28 U) and pH 3.6 (81.43 U) respectively.
Conclusions: Results obtained revealed species- and strain-specific potentials of the yeast strains to improve flavor
and mineral bioavailability of fermented food products. Therefore, the application of these yeasts as starter cultures
during food fermentation process is a very promising method to enhance the flavor profile and enhance mineral
bioavailability in indigenous cereal-based fermented food products.