Dr. Kate Howell, Associate Professor of Food Chemistry at the University of Melbourne, Australia discusses how microbes impact the flavor and aroma of food and beverages and shares how microbial interactions can be used to enhance nutritional properties of food and beverage sources. Ashley's Biggest Takeaways Saccharomyces means sugar-loving fungus. Humans have similar olfactory structures and mechanisms as insects and are similarly attracted to fermenting or rotting fruits produced by Saccharomyces. Research has shown that insects (and humans) prefer yeasts that produce more esters and aromatic compounds. Palm wine is a product that is made from sap collected from palm trees (palm sap) across the tropical band of the world. Fruity flavors appear to be less important to persistence of Saccharomyces strains in an Indonesian palm wine fermentation. This may be because palm wine fermentation is very quick, generally 1-3 days often, with a maximum of 5 days for fermentation to be conducted. Wineries, on the other hand, ferment annually (one fermentation per year/vintage), when the grapes are right. Grape wine fermentations can take 7 days to 2 weeks to complete. So different selections likely take place between the 2 fermentation products. Featured Quotes: When we start drawing our lens on how microbes produce food for humans, we're coopting a process that happens quite naturally. Here I'll start off talking about Saccharomyces cerevisiae, the main fermenting yeast in food and beverage production, because it's one of the most studied organisms and was the first eukaryote to be sequenced. Saccharomyces cerevisiae, as the name implies, loves sugar, and it flourishes when there's a lot of sugar in the environment. Where is sugar found? In fruits, and that's done quite deliberately, because fruits develop sugars and flavors and aromas to attract a birds or insects or anything else that can carry their seeds elsewhere for dispersal. Now, Saccharomyces lies dormant in the environment in a spore before it encounters a sugar-loving environment. And then it replicates very quickly and tends to dominate fermentation. Humans have coopted that into our kitchens, into our meals, into our lives, and we use that process to produce food. As Saccharomyces starts to use this sugar, it balances up its metabolism. And as it does this, it produces aromas. These aromas have a lot of important characteristics. Humans love them, but insects also love them too. I've been interested in the yeasts that are found naturally in sourdough starters. Sourdough is a really interesting system. Because you've got yeast and bacteria interacting with one another. One of the things we are collaborating on with colleagues in France at Inrae, Dr. Delphine Sicard, is to understand some of the non-Saccharomyces yeasts that are naturally occurring in sourdough starters. So here we're looking at a collection of a yeast called Kazachstania humilis and trying to understand how it has adapted to the sourdough environment, how its sustained over time and how different global populations differ to one another. And this, of course, is of interest to the baking industry because not only do artisanal bakers have sort of an undiscovered wealth of biodiversity in their starters, baking companies also have an interest in using different sorts of flavors and bread for the commercial markets. The connection between a chemical profile and a person’s sensory preference isn't something that's complete and direct. So, in every method that we use, there's always caveats, but we try to correlate it. Let's start off with the chemical characterization. We use headspace sampling, analytical chemistry, separation with gas chromatography and identification with mass spectrometry. And we use different 2-dimensional methods to be able to understand what the very small compounds are, and to be able to identify them. We can semi-quantify these to be able to make comparis