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Hops
Hops have been used to make beer in the UK since the early 16th century having been introduced by Flemish brewers in Kent. There had been a great deal of resistance to their use and this is, in fact, the explanation for the terms beer and ale. A fermented malt beverage could only be called “Ale” if it was brewed using the then traditional herbs and spices. Similar beverages brewed using hops were called “Beer”. Nowadays the two words are synonymous.
Once established the advantages of hops soon overcame resistance to their use.
Apart from the sharp refreshing, bitter flavour of hops, the big advantage of replacing spices and herbs with hops was that hops had an antibacterial effect on the spoilage organisms associated with beer and dramatically improved the shelf life.
Hop vines grow from a root stock to a height of some 20 feet or more in the course of a season, which explains why hops can not be grown much further north than Herefordshire in England since they need frost free conditions from March to October
The hop cone is the fruit of the hop and this is picked from September through October.
The hops collected are dried in a special kiln called the Oast House, which forms a striking part of the landscape of hop growing regions.
Once dried the hops are packed into pocket or bales and transferred to a temperature controlled storage area. A low temperature is critical to the shelf life of hops. The volatile hop oils and resins soon dissipate at higher temperatures and the α acids important to the eventual formation of bitterness will similarly deteriorate.
Whole hops, as they are called in this form, are used by many breweries, but the use of palletized hops is becoming more common.
Palletized hops are prepared by shredding whole hops and compressing the resulting powder into pellets. The process is carried out under carefully controlled conditions of low temperature and in an inert atmosphere of nitrogen.
The pellets are then vacuum packed in foil containers.
The arguments for and against using hop pellets are quite entrenched, but many trials have been carried out comparing the use of whole hops against pellets and from the point of view of flavour and quality there seems to be little difference. Here at Broughton we have always used hop pellets.
The main advantages of pellets are:
Consistency: Hops keep fresh much longer in their vacuum packs. They are much easier to weigh out accurately.
Economic: The utilization of the hops is much greater. The extraction of the bitterness is much greater in pellets given the much larger surface area. Whether this argument applies to the hop aroma is open to question, but the largest bulk of hops are used for bitterness.
The storage and transportation of palletized hops is much cheaper given that pellets take up only a fraction of the space required by whole hops and pellets do not require to be stored at such a low temperature.
The importance of hops is in two parts:
The first is a group of compounds found in hops and collectively called α acids. These are very complex carbon chain molecules which dissolve in the boiling wort in the wort kettle and then undergo a chemical change, called an isomerisation, whereby the α acids are converted into isohumulones. Isohumulones have a very bitter flavour and are responsible for as much as 30% of the flavour of beer. It is the isohumulones which have a certain amount of antibacterial action against beer spoilage organisms.
The second is the oils and resins found in hops. These are volatile aromatic compounds which are easily checked for by rubbing whole or palletized hops between the palms of the hands releasing the beautiful aroma. Being volatile very little survives the boiling necessary for the extraction of bitterness, so aromatic hops, specially bred for the aromatic content as opposed to the a acid content are added late in the brewing process. Here at Broughton we add aromatic hops to the whirlpool. The classic example of this is The Ghillie where we use a Hallertau hop in the whirlpool and the aroma is very marked in the final product.
