Epsilon Archive for Student Projects

Abstract

This thesis investigates the concept of microbial terroir in spontaneously fermented beers by comparing the microbial communities and flavor profiles of Belgian Lambic and American Coolship Ale (ACA). The study aims to determine if specific microorganisms tied to geographical locations influence the unique flavors of these beers and how barrel-aging affects their microflora and quality. Spontaneous fermentation relies on natural microflora present in the environment, resulting in unique and complex flavor profiles due to microbial succession through distinct fermentation phases: Enterobacteriaceae, main fermentation, acidification, and maturation.
Key methodologies include DNA amplification, high-throughput sequencing, gas chromatography-mass spectrometry (GC-MS), and gas chromatography-olfactometry, providing comprehensive insights into microbial diversity and volatile compound contributions. The research compares four studies: a study on Lambic from Cantillon's brewery, an industrial Lambic production, traditional Lambic from the Senne Valley, and ACA over three years.
Findings reveal common core microbiota, such as S. cerevisiae, S. pastorianus, D. bruxellensis, and P. damnosus, with variations suggesting microbial terroir. The study highlights significant differences in microbial compositions between Lambic and ACA, influenced by geographical and environmental factors. Insights from other fermented products like sourdough and Baijiu liquor further support the existence of microbial terroir.
This research underscores the complexity of spontaneous fermentation and its potential for producing unique beer flavors. Future studies should focus on controlled conditions and advanced microbial identification techniques to confirm microbial terroir and its impact on beer quality and flavor.