External authors:

• Valeria Galaz ( Pontificia Universidad Catolica de Chile )

Abstract:

Yeasts are ubiquitously present in different natural sources. Some of these yeasts have interesting characteristics for the production of fermented food products. This study characterized Lachancea thermotolerans and L. quebecensis isolated from insects to determine their brewing potential. The yeasts were evaluated according to their fermentative potential in glucose and maltose-defined media and their resistance to ethanol and hop. Finally, craft beer was elaborated at a laboratory scale (10 L). The yeasts utilized glucose as the only carbon source and produced 3.25 +/- 1.77, and 4.25 +/- 1.06% (v/v), of ethanol for L. thermotolerans and quebecensis, respectively. While in the maltosedefined medium, ethanol content reached 3.25 +/- 0.45, and 3.92 +/- 0.36, respectively. The presence of alpha acids and ethanol affected the growth of L. quebecensis, which showed lower growth at 90 IBU and 8 ethanol% (v/v) mixtures. The craft beer brewed with L. quebecensis in monoculture experiments showed fruity flavors associated with ethyl acetate and isoamyl acetate. The ethanol content reached 3.50 +/- 0.46% (v/v). The beer pH was 4.06 +/- 0.20, with a lactic acid concentration of 1.21 +/- 0.05 g/L. The sensory panel identified the beer as "fruity", "floral", "hoppy", "sweet", and "sour". To our knowledge, this is the first time L. quebecensis was reported as a potential candidate for sour beer production with reduced ethanol content.