Contaminantes microbianos en cervezas artesanales embotelladas de la Patagonia andina argentina / Microbial contaminants in bottled craft beer of Andean Patagonia, Argentina

Resumen La actividad cervecera en la Patagonia andina argentina tiene un rol muy importante en la economía de la región; una de las problemáticas que enfrenta, en términos de calidad, son las contaminaciones microbianas. La presencia de bacterias y levaduras contaminantes en la cerveza produce cambios microbiológicos, físicos y químicos, que impactan en sus atributos sensoriales. No obstante, pocas cervecerías establecen criterios y políticas que garanticen la calidad microbiológica de sus productos. El propósito de este trabajo fue estudiar por primera vez la incidencia de contaminantes microbianos en cervezas artesanales embotelladas producidas en la Patagonia andina argentina, además de identificar los principales microorganismos involucrados y determinar posibles relaciones entre los eventos de contaminación y variables fisicoquímicas de la cerveza. Para ello se analizaron 75 cervezas provenientes de 37 cervecerías de 12 localidades andinas. El 69,3% de las muestras analizadas evidenció crecimiento de microorganismos en los medios de cultivo empleados para la detección de contaminantes cerveceros. La bacteria Levilactobacillus brevis y levaduras del género Saccharomyces fueron los principales contaminantes identificados. Se comprobó que las contaminaciones microbianas impactaron sobre el perfil sensorial de la cerveza y que el cambio de pH fue un indicador de contaminación por bacterias lácticas. De cada 10 fábricas estudiadas, 8 presentaron problemas de contaminación, lo que pone en evidencia la necesidad de diseñar estrategias de prevención y control de contaminaciones en microcervecerías.

Abstract The brewing activity in Andean Patagonia plays a very important role in the region's economy, being microbial contamination one of the main problems in terms of quality. The presence of contaminant bacteria and wild yeasts in beer generate microbiological, physical and chemical changes that impact on its sensory attributes. However, few breweries establish criteria and policies to guarantee the quality of their products in a microbiological sense. The purpose of this work was to study for the first time the incidence of microbial contaminants in bottled craft beers from Andean Patagonia, identify the main microorganisms involved and establish relationships between contamination and the physicochemical variables of beer. We analyzed 75 beers from 37 breweries from 12 different Patagonian cities. Our results showed that 69.3% of the analyzed beer exhibited contaminant microorganism growth. Bacteria Levilactobacillus brevis and wild yeasts of Saccharomyces were the main microorganisms responsible for these contaminations. In addition, we found that microbial contamination had an impact on beer sensory profile and also that pH was correlated with the presence of lactic acid bacteria in beer, being an indicator of contamination for these bacteria. In conclusion, we observed that 8 out of 10 breweries studied showed contamination problems, highlighting the need to design prevention and control strategies in microbreweries.

[Microbial contaminants in bottled craft beer of Andean Patagonia, Argentina]. / Contaminantes microbianos en cervezas artesanales embotelladas de la Patagonia andina argentina.

The brewing activity in Andean Patagonia plays a very important role in the region's economy, being microbial contamination one of the main problems in terms of quality. The presence of contaminant bacteria and wild yeasts in beer generate microbiological, physical and chemical changes that impact on its sensory attributes. However, few breweries establish criteria and policies to guarantee the quality of their products in a microbiological sense. The purpose of this work was to study for the first time the incidence of microbial contaminants in bottled craft beers from Andean Patagonia, identify the main microorganisms involved and establish relationships between contamination and the physicochemical variables of beer. We analyzed 75 beers from 37 breweries from 12 different Patagonian cities. Our results showed that 69.3% of the analyzed beer exhibited contaminant microorganism growth. Bacteria Levilactobacillus brevis and wild yeasts of Saccharomyces were the main microorganisms responsible for these contaminations. In addition, we found that microbial contamination had an impact on beer sensory profile and also that pH was correlated with the presence of lactic acid bacteria in beer, being an indicator of contamination for these bacteria. In conclusion, we observed that 8 out of 10 breweries studied showed contamination problems, highlighting the need to design prevention and control strategies in microbreweries.

Influence of Varying Fermentation Parameters of the Yeast Strain Cyberlindnera saturnus on the Concentrations of Selected Flavor Components in Non-Alcoholic Beer Focusing on (E)-ß-Damascenone.

The diversification of beer flavor is becoming increasingly popular, especially in the field of non-alcoholic beers, where sales are growing steadily. While flavor substances of traditional beers can largely be traced back to defined secondary metabolites, the production of non-alcoholic beers with non-Saccharomyces yeasts generates novel fruity flavors, some of which cannot yet be assigned to specific flavor substances. In a recently published study, besides pear, cool mint sweets, and banana-like flavor, distinctive red berry and apple flavors were perceived in a non-alcoholic beer fermented with the yeast strain Cyberlindnera saturnus TUM 247, whose secondary metabolites were to be elucidated in this study. The trials were carried out using response surface methodology to examine the fermentation properties of the yeast strain and to optimize the beer with maximum fruitiness but minimal off-flavors and ethanol content. It turned out that a low pitching rate, a moderate fermentation temperature, and an original gravity of 10.5 °P gave the optimal parameters. Qualitative analysis of the secondary metabolites, in addition to standard analysis for traditional beers, was first performed using headspace-gas chromatography with olfactometry. (E)-ß-damascenone emerged as the decisive substance for the red berry and apple flavor and so this substance was then quantitated. Although (E)-ß-damascenone is a well-known secondary metabolite in beer and this substance is associated with apple or cooked apple- and berry-like flavors, it has not yet been reported as a main flavor component in non-alcoholic beers.