This method describes how to determine the quantity of lime water necessary for softening water used in brewing (brewing liquor) and food production.
Water intended for use as an ingredient in the production of beer (brewing liquor) or other foods
Through the addition of lime water or 'milk of lime,' the hydrogen carbonates and free carbon dioxide are transformed into carbonates and are then largely precipitated:
Ca(HCO3)2 + Ca(OH)2 → 2 CaCO3 + 2 H2O
Mg(HCO3)2 + Ca(OH)2 → MgCO3 + CaCO3 + 2 H2O
CO2 + Ca(OH)2 → CaCO3 + H2O
Calcium carbonate is insoluble and precipitates out. By contrast, magnesium carbonate is to a large extent soluble in water. The addition of one more equivalent weight of Ca(OH)2 transforms magnesium carbonate into insoluble magnesium hydroxide:
MgCO3 + Ca(OH)2 → CaCO3 + Mg(OH)2
However, the amount calculated for this form of water treatment would lead to a surplus of lime in the water (and a higher than desired pH), since an especially high alkalinity is required for the quantitative precipitation of magnesium hydroxide. Therefore, the “split treatment” method, as it is known, is preferred, i.e., the quantity of lime water calculated for the total quantity is added to ⅔ of the untreated water. An excess of lime results, and therefore, the magnesium hydrogen carbonate is also precipitated. The addition of approx. ⅓ of the untreated water diminishes the lime surplus and causes the complete precipitation of calcium hydrogen carbonate. By doing so, the hardness caused by calcium carbonate is entirely eliminated, and the hardness caused by magnesium carbonate is to a large extent as well.
This method describes how to determine whether kernels are cracked as part of the visual and manual inspection of a lot of barley.
Barley intended for the production of malt is to be evaluated on the basis of the characteristics described below.
Visual assessment
This method describes how to determine whether kernels in a lot of barley are cracked by means of the iodine-starch reaction.
Barley intended for the production of malt is to be evaluated on the basis of the characteristics described below.
Detection of cracked kernels is based upon the reaction of iodine with starch. Unprotected starch grains located in the cracks are dyed with iodine, thereby producing a vivid shade of blue, making the cracks easily discernible.