Hops in their natural form as cone hops have been used for centuries in the brewhouse. The first trials to extract the valuable components out of the hops were made by Gehlen in 1803. But only around 1920 was Baron von Horst successful in making hop extracts, which were found to be suitable by scientific brewing institutes. Since then the number of hop products has increased considerably. In this chapter the focus is on the naturally produced hop products. Chemically modified hop preparations will only be touched on.
Why are there hop products at all?
For centuries beer had been successfully brewed with cone hops. But the hops In cone form have certain disadvantages which one tried to overcome with hop products - without chemical modification of the valuable components. .
Disadvantages of cone hops:
After harvesting the dried hops have a specific weight between 100 kg and 150 kg/m³. The large volume makes transportation and storage of the bales difficult. Very large storage rooms were necessary to store a certain quantity of cone hops. As the export increased the volume for transportation was reduced by pressing the hops. Thus the first hop product came into being: pressed hops.
Hop lots of an identical hop variety can be clearly distinguished in their valuable components according to the location. Crop fluctuations also have be taken into consideration by the brewer. Cone hops are difficult to mix and homogenise. The dosage of quantities with variable proportions of resin can only be guaranteed by constantly checking the bitter values.
In connection with oxygen the valuable components of the hops are decomposed oxidatively. The stability of the alpha-acids differs considerably from variety to variety. Once the lupulin glands are damaged then the decomposition accelerates rapidly. In order to maintain the valuable components, after harvesting the hops can therefore only be pressed to a certain degree so that the particular glands are not broken open. It was Important to eliminate this disadvantage as far as possible by developing hop products.
Poor dosage properties:
Low weight and the stickiness of the hop cones make exact dosing difficult. In the face of the size of present-day coppers the automation of the hop dosage would only be realized with difficulty. Years ago hop sieves were necessary to remove the cones from the wort, today too bigger whirlpool overloading would be the result.
Fluctuating concentration of the valuable components:
Up until the mid-1990s generally classic aroma hops were used. Due to the development of hop products efforts were mad to concentrate the valuable components without modifying them.