DIHYDRO-

ISO-ALPHA

ACIDS (RHO)

Purpose:

Dihydro isomerised hop extract is added post fermentation to provide beer with hop bitter flavour and light stability. It makes little contribution to enhanced beer foam stability and is therefore extremely useful when used in combination with tetrahydro-iso-alpha acid to provide beer with light protection without excess foaming properties. Because dihydro-iso-alpha acids have less sensory bitterness (0.6 - 0.8) than normal isomerised alpha acids, more is needed to achieve the desired level of bitterness than with other hop products. Dihydro-iso-alpha acids are produced from CO2 pure resin hop extract using proprietary technology.

Description:

This product is a 30% or 35% solution of the potassium salts of dihydro-iso-alpha acids in water at pH 9.5-10.5. It is produced by a borohydride reduction of iso-alpha acids. It meets all applicable FDA requirements as described in 21 CFR 172.560 (b) (6). Readily pourable amber-coloured liquid. Density 1.01.

Analysis:

Spectrophotometric and high performance liquid chromatographic methods for the measurement of reduced isomerised extracts 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.

Product Use:

The best utilisation of dihydro 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.

The dihydro 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.

Dosage:

Dihydro-iso-alpha acid has about 0.6 - 0.8 times sensory bitterness as normal isomerised alpha acid, this must be taken into account when calculating addition rates.

Dihydro-iso-alpha acid produces little or no beer foam enhancement. It may be used alone or in combination with "tetra" for beer light protection.

If the objective in using reduced 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.

Storage:

The optimum storage temperature for this product is 15-20°C. It is normal for some crystals of dihydro-iso-alpha acids to separate from solution during storage under these conditions. These crystals may be re-dissolved by warming and mixing the product at 50°C.

Packaging:

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

Safety:

No known health hazard in normal use. Non toxic in normal use.

Solutions of Isomerised Extract are alkaline and, therefore, avoid contact with eyes and skin. In the case of eye contamination, irrigate with plenty of water. If symptoms persist, seek further medical attention as necessary.

Non flammable and non-combustible. Spillages should be washed away with plenty of water.

 

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Ó Wigan Products Ltd. 1997