TETRAHYDRO-

ISO-ALPHA

ACID (THIAA)

 

Purpose:

Tetrahydro isomerised hop extract is added post-fermentation to provide beer with hop bitter flavour, light stability, and enhanced foam stability. Because tetrahydro-iso-alpha acids have a greater impact on sensory bitterness than normal isomerised alpha acids, less tetrahydro isomerised hop extract is needed to achieve the desired level of bitterness. "Tetra" is produced from CO2 Pure Resin Extract.

Description:

This product is usually a 10% solution of the potassium salts of tetrahydro-iso-alpha acids in water at pH 9.5-11.0. It is produced by either:

a.

Hydrogenation of iso-alpha acids, or

b.

Separation of beta acid from pure resin extract, purification, followed by oxidation of b Acid, isomerisation of the oxidation product and finally hydrogenation.

 

Tetra products meet all applicable FDA requirements as described in 21 CFR 172.560 (b) (6).

Readily pourable amber-coloured liquid. Density 1.01.

Product Use:

The best utilisation of tetrahydro iso-alpha acids is obtained by distributing the extract uniformly throughout a large volume of beer, avoiding local high concentrations.

It is necessary to dilute the extract with pH adjusted (10.0-11.0) de-ionised water to approximately 1% concentration.

Tetrahydro isomerised hop extract can be injected into the flowing beer stream at some point between the end of fermentation and final filtration, preferably where minimal yeast is present. We recommend injection over at least 70% of the beer volume.

Storage:

The optimum storage temperature for this product is 15oC-25°C. It is normal for some tetrahydro-iso-alpha acids to separate from solution as an oily resin during storage under these conditions. This separated resin should be re-dissolved by warming and mixing the product at 55°C.

Dosage:

Each brewery will need to determine its required dosage rate(s). THIAA’s are about 1.6-1.8 times more bitter by taste than normal iso-alpha-acids (IAA’s). The dosage rate for tetrahydro isomerised hop extract compared to normal kettle bittering depends on two factors.

a.

The difference in utilisation

b.

The difference in sensory bitterness.

 

For foam enhancement alone we recommend addition of 2 ppm - 5 ppm THIAA, added post-fermentation. This would be equivalent to approximately 3.6 ppm - 9.0 ppm sensory bitterness in beer. The remaining bitterness may be derived from any conventional hopping method.

If the objective in using tetrahydro isomerised hop extract is to provide protection against light-struck flavour, 100% of bitterness must be derived from reduced isomerised hop extracts.

For avoidance of light-struck flavour stringent precautions must be taken to avoid even traces of regular hop bittering substances in the wort, yeast and beer. This includes isolation of wort, post pitched beer and a separate yeast handling system.

Yeast used in a brew which has been hopped in the kettle using conventional hopping materials will carry over sufficient adsorbed hop bitter substances to invalidate the protection provided by the reduced isomerised products.

Wigan Products would be pleased to discuss with you the complex properties of isomerised products and advise on specific applications.

Analysis:

Spectrophotometric and high performance liquid chromatographic methods for the measurement of THIAA in extract and beer are available on request. Please note modifications of "E.B.C. 9.6 International Bitterness Assessment in Beer" are required if the beer bitterness is to be correctly assessed.

Packaging:

The Material is offered in 25 litre polyethylene containers with a net weight of 25 kilograms. Other containers can be arranged if required.

 

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Ó Wigan Products Ltd. 1997