Factors Affecting Beer Quality

The activity of yeast cell during fermentation will influence the character of your beer. This can be seen from the fact that cold wort and finished beer are two completely different products as regards beer taste, beer flavor and to a certain extent chemical constituents. The quality of the beer depends on the wort nutrients, yeast stain, equipment as well as the chosen process parameters.

The bio-chemical changes of the wort nutrient during the fermentation as a result of the yeast activity can be broken down into the following categories:

1. Non fermentables components

Such as dextrins (Non fermentable sugar), some nitrogen components for example; protein, peptides and some amino acids and some mineral salts.

2. Fermentable components

Fermentable sugar such as glucose, maltose, maltotriose, sucrose and fructose which are converted into CO2 and ethanol (C2H5OH) and some by-products such as high alcohols, organic acids, aldehydes and ketones, esters, lipids and sulphur compounds.

3. Inner yeast cell released components

These components are released from the yeast cell when it is inactive such as proteolytic enzymes, peptides and phosphates.

4. Outside yeast cell released components

This is the most important component because it makes your beer hazy because of the reaction between protein molecules and polyphenoles, which forms beer haze.

5. Volatile components

Such as Vicinal diketone or VDK (some call “diacetyl”), acetaldehydes, H2S, Isoamylacetate, ethylbutyrate, dimethylsulphide (DMS) and much more.

6. Surface active components

Such as beer color and hop’s bitter components, these components are adsorbed to yeast cell wall and hence are removed from the fermenting beer.

7. Beer infected components

If your beer infected from other microorganisms such as wort bacteria, wild yeast or lactic acid bacteria these organisms can make your beer cloudy, sour and off-flavor.