by Courtney Llewellyn
Yeast are living organisms with very important jobs: They turn other things into alcohol for us! That’s why what you feed your yeast is so crucial when it comes to making cider.
“Why care about yeast nutrition?” asked Anne Flesch, Fermentis regional sales manager, Western North America. (Fermentis, part of a worldwide company that focuses on all aspects of fermentation, recently presented its Fermentis Academy webinar on yeast nutrition.) There are some important answers to that question – done right, it means cider makers can avoid problematic fermentations, avoid off-flavors and characters and emphasize positive aromas.
“Yeast is a flavor engine responsible for up to 80% of aroma-active compounds in beverages,” Flesch noted.
Like any other life form, yeast requires macronutrients for energy and growth (carbon, nitrogen and sulfur) as well as oxygen, fatty acids and sterols. Yeast also need micronutrients for their enzymatic conversions and reactions – vitamins such as biotin, thiamine and pantothenate and minerals like magnesium, potassium, manganese, zinc, iron and copper.
“Nitrogen is key,” Flesch said. “It is a building block of amino acids, and amino acids are building blocks of protein. Nitrogen sources are indispensable at all stages of fermentation.”
Available nitrogen is used for biomass production, fermentation speed and completion, flavor production and the production of other metabolites.
Optimal fermentation comes from a combination of optimal conditions for yeast growth and the optimal conditions for fermentative capacity (the number of viable cells and the vitality of those cells). Nutrient limitation is the first cause of fermentation arrest, and limited nitrogen is most often the cause, according to Flesch.
When yeast receive their proper nutrients (but especially the right amount of nitrogen), you allow them to literally live their best lives. And that allows you to enjoy yours as you sip the fruits of their labor.