Beviale Summit Warm-Up: Combining Lactic Acid Bacteria and Active Dry Yeasts for Sour Beer Production

Sour beers are rather complex and trendy; and they belong to a large number of flavourful beer styles. Nowadays brewers are looking for flavour diversification achieved by mix fermentations, but as well within shorter period of time and with high reproducibility, which can represent a big challenge for craft brewers.

Kettle souring process is an easy way to produce them. In this case, acidity in beers are achieved then by two wort boiling steps. The first one contributes to sterilize the non-hopped wort produced through the mashing step. Then wort acidification is performed by a Lacid Acid Bacteria (LAB) addition in order to trigger lactic acid fermentation in a controlled manner. Annihilation of the living LAB cells is ensured by the following second boiling along with hop additions. Alcoholic fermentation is then performed as for a regular beer production.

Various fermentation combinations between LAB strains (homo or hetero-fermentative strains) and Saccharomyces yeast strains (neutral, fruity, POF+) were designed to produce different sour beers. Biochemical analysis (fermentation kinetics, organic acids production, …) and sensorial evaluation were both performed on the final sour beers. The combinations study shows LAB strains impact clearly flavor profile of the final beers.

By Evelyne Fonchy
Fermentis Technical Manager, Beverage fermentation

The presentation will be in English. However, there will be a Q&A in German and English with Stefan Lupprich.