Monitoring the colour and bitterness of beer

Details Monitoring the colour and bitterness of beer Monitoring the colour and bitterness of beer

1996-09-16

1998-02-10

Warden, Jill

Chemistry: analytical and immunological testing

Food or dairy products

Wine or alcoholic beverages

2504581, 2504591, 250910, 356317, 356318, 356417, 426231, 436131, 436132, 436172, 422 8205, 422 8206, 422 8207, 422 8208, G01N 3314

Patent

active

057168504

DESCRIPTION:

BRIEF SUMMARY
FIELD OF INVENTION

In beer production, it is desirable to ensure that the beer produced has a consistent colour and a consistent taste. To achieve this, it is necessary to monitor both the colour and taste of the beer to ensure it is within acceptable limits.


DISCUSSION OF PRIOR ART

Various methods for measuring the colour of beer are discussed in the paper "The Measurement of Beer and Wort Colour--A New Approach" by Sharpe et al, Journal of the Institute of Brewing, 1992, volume 98, pages 321-324. As described in this paper, the conventional way to measure the colour of beer is using colour glass comparator discs, and to assess the colour by direct visual comparison with these discs. The colour temperature of the illuminant can vary how colour is perceived, and accordingly a standard illuminant is required when using comparator discs. Ageing of the coloured discs and incorrect storage can also cause colour shifts which effect the determination of colour, and the range of disc colours, whilst being wide, tend not to match the exact colour of the beer, for example the yellowness of lager or the brownness of ales and bitters. Further still, the comparison is subjective, and as it is totally manual there may be some inconsistency as the person monitoring the colour becomes fatigued, and additionally between different breweries, and even within the same brewery, with different people carrying out the monitoring.
Some of these problems are overcome by using a spectrophotometric method of measuring. Such a method has been approved by the Institute of Brewing, the European Brewery Convention, and the American Society of Brewing Chemists, all of which recommend the use of a single wavelength spectrophotometric measurement at 430 nm. In such systems, light of 430 nm illuminates the beer sample, and the absorption of light by the beer is determined. From the absorption, the colour is calculated. This system is not suitable for analysis of worts from coloured malts, dark malts or roasted barley which absorb too much light. Further still this system is error prone due to back scattered light from particles suspended in the beer creating a slight haze.
The approach suggested in the above paper is to use a tristimulus method to determine the colour of beer. In this method the beer is illuminated with light of three different wavelength ranges to determine the hue or actual colour, the value, lightness or darkness of the colour, and chroma, vividness or dullness. This system is more accurate than either the use of comparator discs or single wavelength spectrophotometric methods. Use of illumination in each of three different wavelength ranges ensures that the colour of hazy beers and worts are accurately monitored and not falsely assessed as with the single wavelength method, and the resulting assessment is similar to that of the human eye.
The bitterness of beer has conventionally been determined by a taster sampling the beer. Again, such measurements are subjective, and so vary between breweries, and within breweries as the taster becomes fatigued.
The bitterness in beer is largely determined by .alpha.-acids, which are resinous constituents of the hops, as they undergo an isomerisation reaction to produce iso-.alpha.-acids. The iso-.alpha.-acids account for about 70% of the bitterness of beer. A method of determining the bitterness in the laboratory has been developed in which a sample is taken of the beer, and this is acidified. The acidified beer sample is illuminated with ultra-violet light at a wavelength of 275 nm, and the absorption of this light by the sample is measured. The bitterness of the beer is calculated by monitoring its absorption of ultra-violet light.


SUMMARY OF THE INVENTION

According to the present invention, a method of determining one or both of the colour and bitterness of beer comprises the steps of illuminating the beer with light of a predetermined wavelength to cause iso-.alpha.-acids in the beer to fluoresce, detecting the fluorescence over a range of wavelengths using a fluorescenc

REFERENCES:
patent: 3615660 (1971-10-01), Bavisotto
patent: 4751185 (1988-06-01), Ono et al.
patent: 4767640 (1988-08-01), Goldstein et al.
patent: 5272090 (1993-12-01), Gavish et al.
Tomlinson et al "A Novel Method for Bitterness Determination in Beer Using a Delayed Fluorescence Technique", Mar. 1995.
J. Inst. Brew. Mar.-Apr. 1995, vol. 101, pp. 113-118.
Sendra, Jose M. et al., "Determination of .beta.-Glucan in Wort and Beer By Its Binding With Calcofluor, Using a Fluorimetric Flow-Injection-Analysis (FIA) Method," Inst. Brew., Sep.-Oct., 1989, vol. 95, pp. 327-332.
Sharpe, F.R., et al., "The Measurement of Beer and Wort Colour--A New Approach," Inst. Brew., Jul.-Aug., 1992, vol. 98, pp. 321-324.

Affiliated with

Also associated with

Rating

Monitoring the colour and bitterness of beer does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Monitoring the colour and bitterness of beer, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Monitoring the colour and bitterness of beer will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2076607