The Structure of a Yeast Cell

Yeast is a single-celled organism which feeds on sugar, producing alcohol, carbon dioxide, heat and flavour compounds in return. There are many species of yeast existing in nature but the species used in distilling is saccharomyces cerevisiae.

So, what does a yeast cell look like?

As pictured, you can see there are eight key elements of a typical yeast cell: 

1. Capsule. The outer part of the cell wall.
2. Cell wall. The protective layer surrounding the cell which gives the cell structure.
3. Cytoplasmic membrane. The membrane controls the molecules and compounds that come in and out of the yeast cell.
4. Bud. The new “daughter” cell, that eventually splits off from the original “mother” cell.
5. Mitochondria. The “power house” of the cell where respiration occurs.
6. Nucleus. The part of cell containing DNA.
7. Nuclear membrane. The protective layer around the nucleus that controls flow of material in and out of the nucleus.
8. Vacuole. The sac inside the cell containing water and other liquids.

In the Scotch whisky making process, it is only when yeast is added to the wort that fermentation takes place. Under anaerobic conditions (that is, without the presence of oxygen), yeast metabolises sugar, producing alcohol as a by-product. Many congeners (aroma and flavour compounds) are generated during fermentation, so it is a vital contributor to the final smell and taste of the whisky.

If you want to geek out further about fermentation, why not join the Diploma in Single Malt Whisky either online or in-person? In our most advanced course, you’ll take a deep dive into all things single malt over 7 modules. 15 samples are included for tasting and practical sensory assessment. The certified whisky connoisseur within you is waiting.