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Microscopic Details On Yeast - With Maggie Campbell From Privateer Rum

Updated: Sep 6, 2019

Can you please give a short summary of who you are, what you do and how you acquired your extensive knowledge?

I'm the President and Head Distiller of Privateer Rum. I also am the elected Vice-President of the American Craft Spirits Association (ACSA) and serving my second elected term on the Board of Directors there. I serve as the Alumni Advisory Board for the Wine and Spirits Education Trust (WSET) representing all diploma holders from the USA.

I am a current Masters of Wine student. Distilling is my first career and I began to study wine and spirits in formal programs directly after getting my BA in Philosophy. I began with an interest in the whiskey world as I was based in Denver at the time and got to meet and befriend Todd Leopold (Leopold Bros) and Jake Norris (at the time the founding distiller at Stranahan's) who are great folks and were nice enough to encourage me in my career and answer my questions.

I accepted the position of Assistant Distiller at Germain-Robin and made brandy in the Cognac inspired method as well as some apple and pear brandy. Then I took a brief year and a half to work for a boutique wine and spirits distributor to learn that side of the business at the urging of Todd Leopold, which taught me an invaluable amount about how products live out in the market. Then Hubert Germain-Robin met Andrew Cabot the founder of Privateer and connected us back in 2012.

Maggie Campbell - President and Head Distiller of Privateer Rum

For people new to the topic of alcohol production, what is yeast and what is its function?

In simple terms yeast are the microscopic fungus that consume sugar (from grain as malt syrup, fruit, cane, etc) and convert that sugar molecule into alcohol, and Co2 (plus other components important for final flavor). The fungal elements of a microbiome are referred to as mycobiota and this includes the fungus yeast. In general in distilling we start with a sugary liquid called wash that yeast ferments into a dry (no sugar left) alcoholic liquid. We know yeast have finished a fermentation when we measure the sugar content and all sugar is gone and the reading is zero (or very close as there may be some entwined sugars that are hard for the yeast to access or a small amount of un-fermentables). This means sugar is now converted to alcohol thanks to the yeast. At this point a distiller will put the fermented wash into the still to coax out and capture the alcohol vapor.

There is yeast all around us. What could some of the reasons be for a distiller to use yeast that’s naturally present vs other types of yeast?

I love the alchemy of wild yeast and sense of place that it can bring. Wild yeast is a generally accepted industry term for the natural yeast that has not been actively added to a fermentation, but grew naturally. It can be picked up from the air, be introduced from the surface of equipment, or come in on the base ingredient. Much of the yeast that would cause a wild fermentation is in fact from the species we call Saccharomyces Cerevisiae, the same yeast species many distillers inoculate with (added yeast rather than wild). The type of Saccharomyces Cerevisiae would just happen to be the locally occurring strains randomly selected from the environment instead of purposefully selected strain(s) added on purpose.

Of course other local microbiome will also participate in a wild fermentation and the complexity of that natural microbiome will create a unique flavor to the fermentation distinct to that place. Other species of yeasts may be present, but Saccharomyces Cerevisiae is latin for 'sugar eater' and is fact well and naturally suited to convert sugars to alcohol (while also imparting generally pleasing 'esters' which we can think of as flavor molecules). These Saccharomyces Cerevisiae will out compete a lot of other yeasts in a fermentation and take over. In this they are responsible for much of the alcoholic fermentation throughout human history. There is a massive variety of unique and special Saccharomyces Cerevisiae - it is not simply to be thought of as one type of yeast but thousands of yeast strains.