From Pasteur to Pet Bowls: The Continuing Impact of Fermentation Science

Walk into a craft brewery and you immediately notice the precision. Brewers monitor pH curves, fermentation activity, yeast behavior, sugar use, and metabolite formation, and their attention to these variables resembles the approach used in nutrition research. Brewers understand that yeast is a living system that can be directed toward specific outcomes through careful control. This practical knowledge served as the earliest foundation for the science of fermentation, which later entered livestock and pet nutrition. 

The Beginning of Fermentation Science 

The scientific understanding of fermentation began in the late nineteenth century. In the 1870s, Louis Pasteur published Studies on Beer and demonstrated that microorganisms were responsible for both proper fermentation and beer spoilage. His work introduced the idea that fermentation quality depends on controlling microbes rather than allowing spontaneous biological activity. This was one of the first industrial applications of germ theory. 

A decade later, the Carlsberg Laboratory expanded on this foundation. J. C. Jacobsen and Emil Hansen isolated the first pure yeast cultures, including Saccharomyces carlsbergensis, later known as Saccharomyces pastorianus. This allowed brewers to work with a single strain rather than a mixed culture, resulting in more predictable fermentation performance. These discoveries made fermentation a controllable scientific process and established the principles of strain selection and microbial purity that still guide fermentation-based ingredient development today. 

From Brewery Byproduct to Nutritional Building Block  

By the mid-twentieth century, breweries produced large amounts of yeast biomass. Livestock nutritionists began incorporating brewer’s yeast into animal diets in the 1940s, 50s, and 60s because it provided protein, B vitamins, nucleotides, and palatability. The brewing industry had already built an extensive understanding of yeast physiology, including how nutrient availability, temperature, and oxygen influence growth and metabolism. 

Brewers also learned to limit autolysis, the natural breakdown of yeast cells after fermentation. Autolysis produces flavor defects in beer, so brewers tried to reduce it. Later, animal nutrition scientists recognized that controlled autolysis released valuable compounds, including peptides, nucleotides, mannan-oligosaccharides, and beta-glucans. What brewers saw as a defect became a useful means of obtaining functional ingredients. This realization transformed yeast from a byproduct into a purposeful nutritional component. 

The Growth of Fermented Ingredients in Pet Nutrition 

As companion animal nutrition advanced, fermentation-based ingredients expanded beyond simple dried yeast. The same principles used in brewing enabled the development of yeast cultures, isolated cell wall fractions, fungal fermentation products, microbial postbiotics, and precision-fermented proteins. The functional roles of these ingredients are now well understood.  

Yeast cultures are the dried product of yeast grown in a controlled fermentation environment that contains the yeast cells along with the beneficial metabolites, such as organic acids, peptides, and B-complex vitamins, they produce during growth. These cultures became valued for supporting gastrointestinal function, barrier integrity, microbial balance, and improving stool quality in feeding studies. Isolated cell wall fractions such as mannan-oligosaccharides, beta-glucans, citin and chitosan, and phosphopeptides support gut health by binding specific bacterial structures or interact with immune receptors that support innate immune function.   

Fungal fermentation products introduced concentrated enzyme activity that can assist with nutrient availability, including protease, amylase, lipase, and cellulase activity, along with organic acids and antioxidant metabolites formed during fungal growth. Microbial postbiotics provided new opportunities for stability and consistency because they contain non-viable microbial cells along with metabolites that influence gut function. Precision-fermented proteins and lipids created a new category of highly digestible and consistent nutrient sources. These included single cell proteins with balanced essential amino acids, mycoprotein with natural fiber and peptide fractions, microbial oil naturally rich in DHA and EPA, and specific metabolites such as ergothioneine, an antioxidant. 

These ingredients are now used in performance nutrition formulas, sensitive stomach diets, senior support products, immune support blends, and diets where consistency of function is important. Their benefits reflect biological pathways that early brewers noticed through changes in fermentation behavior long before nutrition scientists were able to explain them in molecular detail.  

Fermentation as a Nutritional Design Platform 

Modern fermentation closely resembles engineered bioprocessing. Yeast metabolism can be guided by adjusting aeration, substrate type, carbon-to-nitrogen ratio, temperature, and pH. These variables influence whether yeast increases in biomass, strengthens its cell wall, produces targeted metabolites, or enters autolysis.  

Research and development scientists use these controls to improve nutrient digestibility, influence aroma and palatability, stabilize bioactive compounds, and promote consistency across batches. Fermentation has become a platform for designing targeted functionality rather than an incidental process inherited from another industry.  

A Discipline Rooted in Craft and Guided by Science 

Fermentation still has a craftlike quality because microorganisms respond to subtle environmental cues. Small changes can alter metabolic pathways, which is why brewers relied so heavily on sensory observation. Today, the same biological responses are studied through metabolomics, microbial genomics, and enzyme profiling. Although the tools have changed, the conceptual lineage remains the same. The fermentation-based ingredients used in pet nutrition today can be traced directly back to Pasteur’s research and the pure culture work at Carlsberg. 

What Comes Next  

Fermentation now enables nutritional tools that were not possible before. Microbially fermented proteins can be designed for improved digestibility. Postbiotics can be created with specific metabolite profiles that support immune and antioxidant pathways. Fermented lipid systems can provide more stable sources of Omega-3 fatty acids. Yeast cell wall preparations can be produced with customized ratios of mannan-oligosaccharides and beta-glucans. 

What began as a scientific effort to improve beer quality has become a flexible and powerful platform for modern pet nutrition. Fermentation no longer produces leftover ingredients. It is a design system that continues to expand the possibilities for companion animal health.  

The pet industry is becoming increasingly sophisticated, and success requires both scientific clarity and innovative thinking. BSM Partners brings together leading experts in nutrition science, research, product development, and consumer strategy to help brands navigate this complexity with confidence. Our goal is to support clients in creating products that are not only competitive but meaningful for the pets and people who rely on them. 

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About the Author

Dr. Sydney McCauley is a Board-Certified Companion Animal Nutritionist and earned both her bachelor’s and doctoral degrees at Virginia Tech in Animal and Poultry Sciences. McCauley’s research was in nutritional physiology with a focus on understanding the effects of low birth weight on glucose, fatty acid, carbohydrate, and amino acid metabolism in skeletal muscle and overall metabolic homeostasis during neonatal development.