Physiological performance of Kazachstania unispora in sourdough environments

Dea Korcari,Giovanni Ricci,Maria Grazia Fortina,Claudia Capusoni

doi:10.1007/s11274-021-03027-0

Dea Korcari, Giovanni Ricci + Show 2 more

Open Access

https://doi.org/10.1007/s11274-021-03027-0

Copy DOI

Abstract

In this work we explored the potential of several strains of Kazachstania unispora to be used as non-conventional yeasts in sourdough fermentation. Properties such as carbohydrate source utilization, tolerance to different environmental factors and the performance in fermentation were evaluated. The K. unispora strains are characterized by rather restricted substrate utilization: only glucose and fructose supported the growth of the strains. However, the growth in presence of fructose was higher compared to a Saccharomyces cerevisiae commercial strain. Moreover, the inability to ferment maltose can be considered a positive characteristic in sourdoughs, where the yeasts can form a nutritional mutualism with maltose-positive Lactic Acid Bacteria. Tolerance assays showed that K. unispora strains are adapted to a sourdough environment: they were able to grow in conditions of high osmolarity, high acidity and in presence of organic acids, ethanol and salt. Finally, the performance in fermentation was comparable with the S. cerevisiae commercial strain. Moreover, the growth was more efficient, which is an advantage in obtaining the biomass in an industrial scale. Our data show that K. unispora strains have positive properties that should be explored further in bakery sector.Graphic abstract

Highlights

In the last decade, a great attention has been paid to design new microbial starters for food sector
Yeast strains were cultured in YPD broth containing 10 and 30% glucose or fructose and incubated for 48 h
The K. unispora strains are characterized by rather restricted substrate utilization (Fig. 1): only glucose and fructose supported the growth of the strains

Summary

Introduction

A great attention has been paid to design new microbial starters for food sector. In sourdough preparations the autochthonous microbiota, composed of yeasts and Lactic Acid Bacteria (LAB) confers positive features to the final product, positively influencing the technological, nutritional and organoleptic properties and implementing the shelf-life of the bread (De Vuyst et al 2016; Martorana et al 2018) For these reasons there is a growing interest in sourdough preparations and in investigating the potential of the autochthonous microflora found in spontaneous sourdough fermentations. While the study and the use of LAB species has received considerable attention, the study and the use of non-conventional yeasts for bread dough fermentation has received relatively little attention These yeasts do not always have the leavening ability of bread yeast, they can strongly contribute to improve the nutritional characteristics and the flavor profile of the product. They show a higher tolerance towards stressful conditions such as pH, osmotic and oxidative stress (De Vuyst et al 2016; Zhou et al 2017)

Objectives

Methods

Results

Conclusion