DETERMINATION OF CARBON DIOXIDE IN BEER

A rapid, simple and inexpensive method is described for the determination of the carbon dioxide content of beers.     

A RAPID MANOMETRIC/VOLUMETRIC METHOD FOR THE DETERMINATION OF DISSOLVED CARBON DIOXIDE CONTENT OF BEER IN TANKS

A simple manometric/volumetric method has been devised for the rapid estimation of CO₂ in tank beer by unskilled operators. Tables are provided to allow calculation of CO₂ content of beer at 0°C and 15°C, and results compare satisfactorily with those obtained by determinations made using the Recommended Method of Analysis.     

THE INSTITUTE OF BREWING ANALYSIS COMMITTEE DETERMINATION OF SULPHUR DIOXIDE IN BEER

The method recommended for the determination of sulphur dioxide in beer is a modification of the well-known Monier Williams distillation procedure. For routine purposes a rapid technique combining simultaneous distillation and titration is also described.     

VICINAL DIKETONES IN BEER. PART II: INFLUENCE OF SULPHUR DIOXIDE IN THE DETERMINATION OF DIACETYL IN BEER

The accuracy of the determination of diacetyl in beer using o-phenylenediamine is impaired by the presence of sulphur dioxide. This effect may be overcome when the distillate from the beer is collected in strongly acidic solution¹.     

THE DETERMINATION OF PAPAIN IN BEER

The quantitative determination of papain in beer has been achieved by means of turbidity measurements on a casein substrate. The method, which is quick and simple, will measure activities of the order of 1–20 p.p.m. of crude papain. This will cover any amount likely to be found in beer     

THE DETERMINATION OF DISSOLVED OXYGEN IN BEER

A survey is made of analytical techniques for oxygen determination and a recommended procedure for the determination of dissolved oxygen in beer using indigo carmine, is described. Dissolved oxygen meters and electrodes are reviewed.     

THE DETERMINATION OF SULPHUR DIOXIDE IN MALT

The Institute of Brewing Recommended Method for the determination of sulphur dioxide in beer has been modified for determination in malt. Three inter-laboratory trials are reported and the resulting procedure is described. It has the advantages of being well tried in its general form and employing relatively cheap equipment. While the inter-laboratory reproducibility achieved was not particularly good the method is published for use in laboratories where it may fulfil a present need.     

ON THE DETERMINATION OF VOLATILE THIOLS IN BEER

The method of Ikeya for the determination of volatile thiols in beer by aspiration of these compounds into mercuric acetate has been examined. Cadmium acetate has been found to be unsuitable as an absorbant for removing hydrogen sulphide since it also combines with thiols. This reagent has been replaced by aqueous zinc acetate in a separate absorption trap. The proposed modification has the advantage of enabling estimations of hydrogen sulphide and of volatile thiols to be carried out on the same sample.     

PRODUCTION-SCALE APPARATUS FOR THE INJECTION OF HOP EXTRACTS INTO BEER USING LIQUID CARBON DIOXIDE

Extracts of hops made with liquid carbon dioxide can be substituted for dry hops to introduce the flavour of hop oils into beer. Apparatus has been devised so that such extracts can be redissolved in liquid carbon dioxide and then metered into beer. Successful trials have been carried out on the commercial scale.     

DETERMINATION OF LEAD IN BEER

Three procedures for the determination of low levels of lead in beer were evaluated and compared. The methods were (1) the existing IOB recommended procedure, (2) a dry ashing/AAS procedure and (3) a mixed solvent (xylene/2-heptanone) extraction of the DDDC complex. All three methods gave satisfactory results.     

DETERMINATION OF THE FILTERABILITY OF BEER

A method for the determination of the filterability of beer has been evaluated by members of the European Brewery Convention Analysis Committee. The method is based on the filtration of a beer sample, with a standard amount of diatomaceous earth (DE), under standardised conditions. Repeatability of the test was quite good, however the predictive value of the test is still questionable since no direct correlation could be established between the different filtercake values and industrial filtration problems. No collaborative test was performed as the filterability has to be determined on unfiltered beer; the test is easy to run, and as for the other filterability tests, day to day practice in a brewery will reveal its usefulness.     

THE DETERMINATION OF IRON COPPER AND CALCIUM IN BEER

The atomic absorption methods for iron, copper and calcium in beer, published by the American Society of Brewing Chemists, are recommended.     

DETERMINATION OF TOTAL SULPHUR DIOXIDE IN BEER BY FLOW INJECTION SPECTROPHOTOMETRY USING GAS-DIFFUSION AND THE MERGING ZONES TECHNIQUE

A flow injection system for the determination of total sulphur dioxide in beer is described. The methodology involves the same colorimetric reaction of the reference method between SO₂, prosaniline and formaldehyde. The sample is introduced into the manifold without previous pretreatment, the hydrolysis process, isolation of the SO₂ from the matrix and the colorimetric reaction, being carried out inside the flow tubes. To isolate the SO₂, a gas-diffusion unit was included in the system and to minimise p-rosaniline consumption, a merging zones technique was used. The results obtained were in good agreement with a reference method (relative deviations lower than 5%), the precision being better than 2.5% (relative standard deviation). A sampling-rate of 30 samples per hour was obtained and the consumption of p-rosaniline was reduced 10 fold when compared to the reference method.     

USE OF TITANIUM DIOXIDE AS A CATALYST IN THE KJELDAHL DETERMINATION OF THE TOTAL NITROGEN CONTENT OF BARLEY,MALT AND BEER

Titanium dioxide can be used to replace selenium in the Kjeldahl determination of total nitrogen without sacrifice of precision; higher temperatures for digestion are required than when selenium is the catalyst.     

ADDITION OF HOP EXTRACTS TO BEER USING LIQUID CARBON DIOXIDE*

A method is described for imparting hop character to beer using extract prepared by treating hops with liquid carbon dioxide. The long contact times required for conventional dry-hopping techniques are avoided, and the use of liquid carbon dioxide as a medium for dispersal of the extract obviates problems due to residual organic solvent or emulsion stabilizers. Beers in which hop character was introduced in this way were found to be similar in flavour to control beers treated with portions of the same hop extract dissolved in ethanol.     

DETERMINATION OF TOTAL CARBOHYDRATE IN BEER

A colorimetric procedure for the determination of total carbohydrate in beer has been evaluated in a collaborative trial. The method is recommended by the Analysis Committee.     

DETERMINATION OF SILICONE ANTIFOAM IN BEER

An atomic absorption method is described for the determination of polydimethylsiloxane residues in beer, in the concentration range 0.02–0.5 mg/litre. Actual levels found were 0.02–0.15 mg/litre from fermentations treated with 2–3 mg/litre silicones.