Ozonia, Chlorine, Specific gravity determination are some of the chemical tests that are very necessary in the production of brewed products such as lager beer and malt drink. These tests enable the brewer to establish standards for all the products he brews and also ensures that quality control parameters are maintained throughout the brewing process.
We shall examine three of these chemical tests:- Thus, Ozonia, Chlorine, Specific Gravity Determination.
Ozonia test is also called saproxide test. It is carried out as follows:
10ml of a wort sample is added to 20ml of 25% hydrogen tetraoxosulphate(IV) acid, 1ml of ammonium molybdate and 1g of potassium iodate, KI. This mixture is titrated with 0.1M sodium thiosulphate. When the color is becoming faint yellow, 2 or 3 drops of starch indicator is then added and titaration continued until a clear color is obtained. You then take the titre value and multiply it by 0.06
Chlorine determination in water
50ml of a wort sample is added to a small quantity of potassium iodide, KI and 5ml of acetic acid is also added to this mixture. 2 drops of starch indicator is also added. This mixture is then titrated with thiosulphate and watched for a color change, which is decolorization from pink. The end point is noted and the chlorine content is calculated as follows:
Chlorine content = End point x 35.5 x 0.02 x 1000/50
Specific Gravity Determination
The determination of the specific gravity of a wort sample from a brew house is as follows:
A density bottle is washed thoroughly and dried in an oven. The weight of the density bottle is taken with its cover on it. When cooled in the desiccators. Its weight is read as A. you then fill the density bottle with distilled water and weigh again and then record as B.
Therefore, the weight of the distilled water will be weight of the density bottle, B with water minus weight of dry density bottle A. that is, B-A = C. the water from the density bottle is discarded, rinsed with the test sample(wort) and filled with the sample and reweighed as D. Subtract the weight of the density bottle from the weight of the density bottle containing the test sample so as to get the weight of the test sample which is recoded as D
Specific gravity= weight of sample/weight of distilled water