What do marmite, gelatin, and molasses all have in common? They’re all foods that begin as byproducts of some other food – in this case, beer, meat, and sugar. You might not think of cattle while eating jelly or yeast while spreading Marmite on your toast, but rest assured, without one, you would not have the other.

Marmite, Vegemite, and other spreads like them are made from the dregs of the beer-brewing process. After brewer’s yeast has done its job of converting sugar into alcohol, it’s scooped up with a slurry of other ingredients, and ferried to a factory where it begins the process of being converted to something more closely resembling food (if you’re on the side which finds such concoctions edible).

There, the yeast cells are burst and the proteins and other substances from their interiors are separated from the cell walls using a centrifuge. That thick soup of protein is allowed to ripen, with enzymes native to the yeast busily breaking down molecules. Amino acids, the component parts of proteins, help give a rich, savory taste, and so the more the enzymes are allowed to work, the more umami the product. Evaporating off excess water and adding flavouring ingredients are the finishing touches that bring a yeast extract to fruition.