Humulus lupulus L. - Yeasts found on wild-growing hop plants and preliminary insights in their brewing characteristics

Abstract

HOP SPECIAL

This study focuses on the microfungal community found on hops, and because little data has been available until now, also seeks to increase the body of knowledge on these microfungal communities. Additional benefits may also be gained for brewers who use fresh hops in dry hopping and for beer styles that extensively rely on the technique of dry hopping by providing brewers with insights into which yeast species can enter the beer through hop cones, whether desired or undesired. In this context, the following considerations also come into play: Industrial production of beer requires reproducibility and consistent quality. Wild yeast species are usually undesirable and are considered contaminants. Conventional brewing uses only a few brewer's yeast strains that have been selectively bred over decades. Despite this, the so-called craft beer revolution has led to the spread of spontaneously fermented beers, for which the natural yeast diversity plays a crucial role. For brewers of such beers, the regional microbiome represents an invaluable resource. The biodiversity of the yeast microbiome that naturally occurs on brewing materials, such as hop cones, as well as its fermentation properties, can provide a competitive advantage. The identified yeast and microfungi species which were found in this study on wild hop plants were: Rhodotorula mucilaginosa, Papiliotrema flavescens, Moesziomyces aphidis, Debaryomyces hansenii, Hanseniaspora uvarum, Fusarium sporotrichioides, Meira spp. , Wickerhamomyces spp. and Starmerella spp.