Investigation of carbon–sulfur lyases in brewing yeast and their impact on nitrogen scavenging and volatile thiol release during beer fermentation
Tracks
Plenary 1
| Thursday, March 6, 2025 |
| 11:40 AM - 12:00 PM |
Speaker
Mr. Avi Shayevitz
Research Scientist
Lallemand Inc.
Investigation of carbon-sulfur lyases in brewing yeast and their impact on nitrogen scavenging and volatile thiol release during beer fermentation.
Abstract
Carbon-sulfur lyases (CSLs), among other things, play an important role in nitrogen scavenging, detoxification, and redox balancing in eukaryotic metabolism. Previous research demonstrates the value of Saccharomyces cerevisiae-derived CSLs such as D-cystine-desulfhydrase and cystathionine beta-lyase in liberating volatile thiols from cysteinylated precursors (e.g., c-3MH, c-4MMP), thereby enhancing tropical aroma notes in wines, especially those from Sauvignon blanc cultivars. Similarly, plants like Humulus lupulus (hops) and Hordeum vulgare (barley) - abundant in analogous precursors - are presumed to experience comparable enzymatic benefits in the presence of S. cerevisiae. While CSLs are commonly associated with nitrogen scavenging in nutrient-poor settings such as grape must, their role in brewer’s wort is less clear. It has been speculated that CSL-encoding genes such as IRC7 can enhance aroma perception in beer in much the same way that does in wine. However, active nitrogen repression in nutrient-dense wort and other environmental factors may prevent efficient conversion of hop-derived cysteinylated precursors. To better understand this interaction, this study explores the effects of temperature and yeast-available nitrogen on a set of genetically diverse brewing yeast, with characterized IRC7 genotypes along with a modified IRC7-knockout control. Comparing sensory, chemistry, and fermentation data has demonstrated that while IRC7 may play in important role in nitrogen scavenging and subsequent thiol release, its overall usefulness in beer is likely more nuanced than previously thought.
Biography
Ronald Samia is a 4th year PhD student in Oregon State University's Food Science & Technology Department in Dr. Tom Shellhammer's lab. Ron has a B.S. in Biomedical Engineering from Rutgers University in New Jersey, and an M.S. in Bioinformatics from the New Jersey Institute of Technology, and over 13 years of experience working in the Biopharmaceutical Industry. At Celgene Corp. and Novartis Pharmaceuticals, he specialized in developing novel genetically engineered T-Cell cancer therapies, their manufacturing processes, and tech transfers to launch new sites globally. His interest in homebrewing and the science and art of beer led him to pursue his brewing science degree. At Oregon State University, Ron’s research encompasses wildfire smoke impact on hop quality and hop-yeast interactions during fermentation with a focus on bio-transformative changes to hop aroma.
Avi Shayevitz is a R&D scientist for Lallemand Inc. whose duties include the development, improvement, and implementation of microbiological brewing solutions. His professional background includes industrial chemistry, biochemistry, fermentation microbiology, and brewing technology. He received his graduate education in Food Science and Technology from Oregon State University through the magic of bioinformatics modelling of microbial population dynamics in barrel-aged beer fermentation and maturation, as well as studying how barrel origins may influence maturation outcome. Originally hailing from Detroit, MI, he now lives and work in Montreal, Quebec where he lives a mostly quiet life learning French and drinking Sortilège.
Dr Tom Shellhammer is the Nor’Wester Professor of Fermentation Science and a Professor of Food Science in the Department of Food Science and Technology at Oregon State University where he carries out research, teaching and outreach activities focused on beer and raw materials quality with particular attention paid to hops. He is a former President of the American Society of Brewing Chemists and the former President of the District NW Master Brewers Association of the Americas. From 2007 – 2023 he served on the Board of Examiners of the Institute of Brewing and Distilling. He is a Fellow of the Institute of Food Technologists and the Institute of Brewing and Distilling.
