Brewing Characteristics of the Maltotriose-Positive Yeast Zygotorulaspora florentina Isolated from Oak

Jarkko Nikulin,Brian Gibson,Ronja Eerikäinen,Mathias Hutzler

doi:10.3390/beverages6040058

Abstract

The use of wild yeasts in fermentation is becoming a viable option for the differentiation of beers. To achieve good fermentation rates and alcohol yields, however, such yeasts must have the ability to utilize the wort sugars maltose and maltotriose, a relatively rare trait amongst non-domesticated yeasts. Zygotorulaspora florentina is a species with the ability to utilize both sugars, and was evaluated here with respect to its brewing potential. The strain studied (VTT C-201041) was isolated from bark of an oak tree (Quercus robur) in Espoo, Finland. The fermentation performance of the strain was compared to that of two ale yeasts as well as the species type strain (VTT C-94199). Both Z. florentina strains fermented wort efficiently (apparent attenuation levels >77%). While the type strain had the highest yield, the Finnish strain produced more volatile aroma compounds. The species is capable of decarboxylating ferulic acid to produce the spice/clove-like compound 4-vinylguaiacol, which was present in beers at a concentration above the typical flavor threshold. The characteristic flavor of 4-vinylguaiacol was not however perceptible in taste trials, possibly due to the masking effect of other compounds. The potential of this species for industrial application is discussed, particularly in relation to its apparent ethanol sensitivity.

Highlights

IntroductionA long trend of increasing beer production volumes peaked in 2013 at 1.97 billion hL [1], but has been steadily decreasing ever since [2]
The past decade has witnessed significant upheavals in the brewing industry
In 12 °P wort, the alcohol by volume (ABV) levels produced were comparable to a commercial ale yeast due, in particular, to their ability

Summary

Introduction

A long trend of increasing beer production volumes peaked in 2013 at 1.97 billion hL [1], but has been steadily decreasing ever since [2]. The craft beer boom made small-scale breweries serious players in beer markets and third, towards the end of the decade, the low and non-alcoholic beer category started to live up to the expectations set up for years [3]. These trends reflect the changes in the habits of beer drinkers. There is a general interest in new processes to differentiate beers and a growing appreciation of the potential of non-conventional yeast species to create novel flavor profiles, or limit alcohol content [3,5,6]

Methods

Results

Conclusion