Yeasts are the microorganisms mostly used in the fermentation process of food and beverages. They are especially important in the process of beer fermentation, which is the most consumed fermented beverage in the world. In this project, four different strains of yeasts from farms in Norway’s municipalities Ål and Hornindal, specifically NFAY 29, NFAY 30, NFAY 31, NFAY 32, were used. Besides, we used four controls; one of them was provided by the National Yeast Collection of UK (NCYC 456), two of them by WhiteLabs (WLP013 and WLP500) and the last one by a farmhouse in Norway (G561). The objective was to perform a genetic identification of each of these strains and the study of their fermentation properties. To carry out the genetic analysis, a taxonomic classification was made, based on the large subunit 28S ribosomal RNA (LSU) to find out the genus, and in the transcribed internal space region (ITS) to identify the species to which they belonged. To carry out the study of the properties of fermentation, we used the techniques of gas chromatography coupled mass spectrometry with head space injection (HS/GC-MS) which revealed clear differences between fermentations at different temperatures; and analysis of liquid chromatography coupled to mass spectrometry (LC-MS), which allowed us to determine the ability to use maltotriose, one of the main substrates used by yeasts to grow.

Keywords: Food Chemistry, Yeast, Fermentation, Beer.