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PRODUCT INFORMATION LEAFLET

BASE EXTRACT

(HOP OIL / BETA ACID EXTRACT)

BASE EXTRACT - the residual extract remaining following the removal of the alpha acids from a whole CO2 extract. It may serve several roles in the brewing process. General Description: Base extract consists of whole extract from which the alpha acids have been removed. It consists mainly of beta acids, other resin material and hop oils. It can be used to balance the flavor of beer bittered predominantly with isomerized or reduced hop extracts. Base extract also helps ensure that fermentation proceeds in a normal fashion.

Preparation: Hops are extracted using liquid CO2 at a temperature of 7 - 10° C and a pressure of 50 - 55 kg / cm2. CO2 is removed and the extract recovered at a temperature of 14 - 15° C. The alpha acids are isomerized and removed from the other hop material which becomes the base extract.

Composition: The precise composition of base extract obviously varies markedly depending upon the specific hop variety used. A generalized analysis is shown below:

Constituent Composition (%w/w)

Alpha acids and isomerized 1 - 2

alpha acids (residual)

Beta Acids 40 - 60

Uncharacterized soft resins 10 - 20

Essential Oil 4 - 10

Water 0 - 10

Fats and Waxes 12 - 20

Fines 0 - 4

Hard Resins None

Pigments None

Tannins None

Inorganic salts None

Residual solvent None

Uses and Advantages in Brewing: Where beers are bittered predominantly with isomerized or reduced extracts the use of base extract in the kettle serves a number of important functions:

 

 

· It assists a smooth rolling boil

· It provides a small amount of normal isohumulone bittering

· It adds non-isohumulone bittering

· It adds hop essential oils

· It ensures a normal fermentation  

Methods of Use: Cans of base extract are normally used by opening or piercing them at both ends and suspending them in a wire basket in the boiling wort. Base extract in drums can be pumped directly from the drum into the kettle.

Addition time is similar to that used for leaf hops or pellets. Quantities for addition are often calculated as 50% of the amount of whole extract which would be used for that volume of wort. Alternatively, as a general rule, an addition rate of 10g base extract/hectoliter is a good starting point for evaluation.

Typical Brewing Performance: The contribution of bitterness from base extract depends upon the level of residual iso- and alpha acids, the degree of oxidation of the beta acids, and the length of time the extract is in the boil. It is therefore a complex question which is best determined by brewing trials.

Similarly, the intensity of hop flavor and aroma will, of course, depend on the time of addition.

It is recommended that base extract be added at the time of addition of whole extracts, and the level of bitterness and aroma be adjusted by a combination of varying addition times in subsequent brews and by post-fermentation additions.

Options: Base extracts can be provided in varying forms. The 'normal' form can be further purified to remove much of the residual alpha and iso-alpha acids. Furthermore, the hop oils can be almost totally removed or standardized to a specific level.

Availability: 'Normal' base extract is readily available, however the purified or oil standardized forms need to be prepared by special order. Similarly base extracts from specific varieties are less readily available.

Methods of Evaluation: Pilot trials and evaluations are recommended to gain experience with base extracts. Taste tests will suggest rate and timing adjustments. Technical assistance with the product is available upon request.

Physical Properties: Viscous paste; becomes fluid on warming to 50°C.

Chemical Properties: Soluble in ethyl alcohol and other polar, organic solvents.

Packaging: Sealed, food lacquered cans of 1,2,5 and 10 kg. Sealed food lacquered steel drums of 200 kg.

Storage: No special storage conditions are required, though prolonged exposure to temperatures in excess of 40°C (104°F) should be avoided. Only full, unopened containers should be stored for long periods of time.