Sarajevska Pivara Beer Composition

4. AIM AND GOAL OF THE DETERMINATION

The aim of this work is to predict the lifetime of the chosen Sarajevska pivara beer (which will be marked AH in this work) by the accelerating aging test (the Forsir method) by measuring the fuzziness of the beer under the angles of 25⁰ and 90⁰.

To achieve the goal set, it is necessary to examine the following during the process of the accelerating aging: Chemical structure of the beer (the share of the alcohol, the real and the apparent extract, extract in the primary wort, the share of O2 and CO2, calorific value) Other indicators of the quality of the beer:

Stability and intensity of the colour of the beer during the process pH value

Bitterness

Total polyphenols

Diacetyl

Foam stability

The air

5 mL of the sample tempered at 20 oC is taken by the pipette in the cuvette for the centrifugation. 0,2 mL 6 mol/dm3 of hydrochloric acid and 10 mL iso-octane (2,2,4-trimethylpentane) is added to the cuvette for the centrifugation, and shaken for 15 minutes in the shaker, and then centrifuged for 10 minutes at 3000 rounds per minute. The absorbance of the iso-octane extract is measured on the spectrophotometer at 275 nm in cuvette of 1 cm, with respect to the blank test which was the iso-octane of the same quality.

The programmed method for the bitterness of the beer caused the calculated values on the spectrophotometer by the following formula:

The standard values for the beer are 10-40 BU, depending on sort, type and origin.

Total polyphenols (EBC method)

The method is based on the fact that, in alkaline medium, polyphenols react with iron (III) ions with the formation of the colored compexes, and the obtained brown colout is measured spectrophotometrically. For more precise determination of some phenolic ingredients, usage of more powerful chromatographic procedures is

This solution was stable for a month 3,5% iron (III) ammonium citrate: 3,5 g of iron (III) ammonium citrate, green (16% Fe), is dissolved in H2O and filled up to 100 mL. The solution was used for seven days, and then it was made again ammonia, diluted: 1 part of the concentrated ammonia is diluten with H2O with the ratio 1:2

Procedure

The sample of the beer is freed from the carbon dioxide in the Erlenmyler flask by shaking. 10 mL of the examined sample and 8 mL of the CMC-EDTA solution is pipetted into the measuring flask and then mixed well. 0,5 mL of the iron (III) solution and 0,5 mL of the diluted ammonia solution is added. After every addition of the reagents, the solution is mixed well. The measuring flask is filled with H2O up to 25 mL, mixed and left in the dark place for 10 minutes. After 10 minutes, the absorbance is read at 600 nm in 1 cm cuvette with respect to the blank test. Blank test was prepared by taking 10 mL of the sample together with 8 mL CMC-EDTA solution and 0,5 mL of diluted ammonia solution,