By Cristina Úbeda Aguilera, M. Carmen García Parrilla and Marina González Ramírez
Yeast, such as Saccharomyces cerevisiae, plays a crucial role in fermentation and winemaking industries, as well as has proven to be a powerful and versatile tool with unique metabolic capabilities for the industrial production of several interesting molecules. During alcoholic fermentation, S. cerevisiae produces a wide range of secondary metabolites. These include volatile compounds that impact the sensory properties of fermented products and bioactive compounds like metatonin (MEL) and hydroxytyrosol (HT), which are associated with health promoting benefits, including antioxidant and anti-inflammatory properties. HT is a well-known antioxidant possibly involved in cell-detoxifying mechanisms. Despite the relevance of these compounds, the conditions for their production are neither well known nor well-controlled.
We delved into the relationship between the production of bioactive compounds such as MEL and HT and the synthesis of volatile compounds across different S. cerevisiae strains. Firstly, an intriguing inverse correlation had observed: strains that produce higher concentrations of bioactive compounds tend to synthesize fewer volatile compounds, particularly higher alcohols like 2-phenylethanol (2-PE) and key esters such as ethyl hexanoate and ethyl octanoate. This phenomenon may be linked to how S. cerevisiae manages metabolic stress during fermentation. The proposed detoxification strategies of the strain could be:
- Producing higher alcohols and their derivative esters
- Synthesizing antioxidants like MEL and HT
For example, a modified S. cerevisiae strain (Aro4pK229L) engineered to overproduce HT did not show a notable reduction in other key esters. This underscores the critical role of nitrogen metabolism in these metabolic decisions. However, the nitrogen demands were not considered.
Secondly, an experimental design closer to wine making conditions might be of interest, from a practical point of view to study nitrogen yeast requirements.
Nitrogen requirements
Nitrogen metabolism is a key driver of compounds production in S. cerevisiae. A study on four commercial strains (Red Fruit®, Uvaferm VRB®, Lalvin Rhone 2323®, and Lalvin QA23®) revealed that strains with higher nitrogen demands exhibited unique metabolic responses. For instance, Uvaferm UVR, known for its high nitrogen requirement, stood out in the production of both HT and MEL despite its limited growth. Interestingly, Uvaferm UVR also produced the highest total concentrations of volatile compounds. This finding highlights how different S. cerevisiae strains respond uniquely to fermentation conditions, suggesting strain-dependent approaches to balancing sensory and bioactive compound production.
Figure 1. Daily growth of each strain and density of the fermented must.
Table 1. Nitrogen requirements study for each yeast.
Implications for the Industry
Considering our aim, the production of wine with more bioactive compounds without compromising the organoleptic quality, it is crucial to understand the metabolic interactions in S. cerevisiae. It has significant implications for the fermentation industry such as, selecting specific strains can optimize both the sensory properties and health benefits of fermented products. For instance, a strain like Uvaferm UVR could be ideal for products aiming to maximize antioxidant content. In other words, developing fermented beverages with higher levels of MEL and HT could open new opportunities in the functional food and nutraceutical markets.
Conclusion
The versatility of Saccharomyces cerevisiae as a bioreactor underscores its importance in modern biotechnology. Its ability to produce both bioactive and volatile compounds highlights the complexity of its metabolic pathways and provides fertile ground for research and industrial innovation. As the food industry increasingly focuses on health-oriented products, understanding and leveraging these metabolic interactions will be key to creating products that are not only delicious but also beneficial to health. However, it is still necessary to conduct more research studies deep inside yeast metabolism to reach the ideal concentration of each precursor.
1. Gonzalez-Ramirez, M., Kazakova, J., Garcia-Serrano, P., Ubeda, C., Valero, E., Cerezo, A. B., Troncoso, A. M., & Garcia-Parrilla, M. C. (2024). Commercial wine yeast nitrogen requirement influences the production of secondary metabolites (aroma, hydroxytyrosol, melatonin and other bioactives) during alcoholic fermentation. International journal of food microbiology, 421, 110788. https://doi.org/10.1016/j.ijfoodmicro.2024.110788
2. Gonzalez-Ramirez, M., Marin-Torres, M.M., Gallardo-Fernandez, M. et al. (2024) Approaching Study on the Relationship Between Saccharomyces cerevisiae Production of Tyrosol, Hydroxytyrosol, and Melatonin with Volatile Compounds in Fermented Must. Food Bioprocess Technol 17, 154–168. https://doi.org/10.1007/s11947-023-03108-y
Análisis metabolómico y de actividad biológica en procesos respiro – fermentativos dirigidos a la reducción de etanol en vinos (PID2022-137807OB-C22)
Dr. Cristina Úbeda Aguilera is associate professor at the University of Seville (Spain). She has a graduate degree in Pharmacy and master’s degrees in microbiology applied to industrial biotechnology, Nutrition and Dietetics and Food Safety. During her PhD (2012), she acquired knowledge in techniques for fermented beverages secondary metabolites analysis and also, performed sensory analysis in different food matrices. Her postdoc experience took place in Chile, focusing her research into two main lines: the study of certain technologies to improve Chilean sparkling wine quality and the search of new yeast strains of interest for the food industry.
Marina González Ramírez is a PhD student at the University of Seville (Spain), at the department of Nutrition and Food Science. She studied Pharmacy at the same university and a Master´s degree in Nutrition and Health. During her PhD she is gaining experience in fermentation procedure and HPLC-MS/MS.