HVG Germany: Hopfen

There are analogies between the raw commodity of hops and the product beer. The hop components react just like the beer:

  • • sensitive to oxygen
    • sensitive to temperature and change of temperature
    • sensitive to light
    • sensitive to time (aging)

In the chapters on the hop varieties and the hop products we have seen that the brewer has a wide range of choices available. Hop products are homogenous, comparatively durable and are controllable in their application. The respective use is dependent on the brewer's goal:

  • • to impart a "basic bitterness" in the beer with selected bitter hop varieties
    • to achieve a balanced aroma as a "flavour profile" in the beer with classic   aroma hops
    • to impart physiologically valuable tannins in the beer for "digestibility" with special aroma hops.

Hops in the brew-house

Traditionally the hopping takes place In the wort copper. The time for the dosage varies from the first wort hopping, via the additions directly before casting, up to direct aroma hopping in the whirlpool. After being dosed the hop components pass through the following stages:

  1. mechanical distribution
  2. emulgation i.e. dissolving the components
  3. components are transformed by heat
  4. evaporating volatile (partly undesired) hop oils
  5. partially combining with proteins and precipitation

At the same time the following processes occur during the wort boil:

  • • Bitter substances: alpha isomerises to iso-alpha-acid, dissolving other components of the resin fraction like the humulinic acids
    • Aroma substances: dissolving, evaporation, oxidation
    • Polyphenols: dissolving, polymerizing, precipitation