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

Omotade Richard Ogunremi,Renu Agrawal,Abiodun Sanni

doi:10.1186/s43141-020-00031-z

Abstract

BackgroundProbiotic 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 strain-specific. 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). ResultsA 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 higher-alcohol 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. ConclusionsResults 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.

Highlights

Probiotic strains are incorporated into food substrates to contribute to fermentation process
They had been identified as Pichia kluyveri LKC17, Issatchenkia orientalis OSL11, P. kudriavzevii OG32, P. kudriavzevii ROM11, and Candida tropicalis BOM21 by sequencing D1/D2 region of large subunit of 26S rDNA gene
Phenyl ethyl alcohol was noted to be the largest proportion of alcohol produced by I. orientalis OSL11, P. kudriavzevii OG32, and P. kudriavzevii ROM 11

Summary

Introduction

Probiotic strains are incorporated into food substrates to contribute to fermentation process. Several authors have reported the probiotic potentials of yeast strains from several indigenous fermented foods and beverages: burukutu, cheese, fura, gowe, kunu-zaki, mawe, nunu, kefir, ogi, olives, and wines [4,5,6,7,8,9,10,11] Most of these yeasts are non-Saccharomyces species, including strains of Debaryomyces hansenii, Issatchenkia orientalis, Galactomyces geotrichum, Kluyveromyces marxianus, K. lactis, Pichia farinosa, P. anomala, P. kudriavzevii, and Yarrowia lipolytica. Technological suitability, including contribution to appealing flavor and improvement of nutritional value, are desirable for the selection of probiotic strains to be incorporated in non-dairy food systems, especially cereal models [12]. VOCs, including organic acids, esters, and higher alcohols determine the distinctive bouquet of the fermented product, contributing fruity, flowery, spicy, coffee to meaty nuance [14,15,16,17,18]

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Discussion

Conclusion