As is the case with drinking water, water employed for the production of beer and soft drinks must be neutral in odor and taste.
beer, beer-based beverages, non-alcoholic beverages, mineral water
A qualitative test is performed after shaking the water in a sealed, odor-neutral bottle. Water possessing an odor is measured quantitatively on the basis of a sensory threshold. Water possessing an odor is diluted with odorless water until the odor is barely perceptible (by at least three people). The ratio of the total volume (water with odor + odorless water) to the volume of the mixture containing the water sample is designated as the odor threshold. The taste test should always be performed after evaluating the odor, since the perception of odor can be influenced by flavor.
This method describes how to determine the capacity for water imbibition (moisture uptake) in barley.
Barley intended for the production of malt is evaluated on the basis of its capacity for water imbibition.
Barley is steeped according to a defined scheme, and the absorption of the steeping liquor by the kernels at defined times is determined by calculating the moisture content. The moisture content after 72 h steeping time is used to assess the absorption of steeping liquor or the capacity for water imbibition in barley.
Whole hops intended for use in beer brewing or elsewhere in the food industry
Evaluation of the appearance of hop cones is performed through visual and manual inspection.
Whole hops intended for use in beer brewing or elsewhere in the food industry
Evaluation of the appearance of hop cones is performed through visual inspection and sensory assessment.
As with drinking water, the water used in the production of beer and non-alcoholic beverages must exhibit a neutral odor and flavor.
Water intended for use as an ingredient in the production of beer (brewing liquor) or other foods
A qualitative check is carried out by first filling an odorless bottle with the water sample, sealing the bottle and then agitating the sample through shaking. For a quantitative determination, if water exhibits an odor, the sensory threshold of the odor in the water is determined. To do so, the water is diluted with odor-free water to such an extent that the odor is barely perceptible (by a minimum of three individuals). One defines the odor threshold value as the ratio of the total volume (odorous water + odor-free water) to the volume of the water sample contained in the mixture. The taste test must always be carried out after the odor test since the sensation of odor is influenced by the sense of taste.
Determination of formic acid by enzymatic means
This analysis is suitable for wort, beer, beer-based beverages and NAB.
Formic acid can be found in beer in small quantities, and it is also formed by contaminating bacteria, for example, by lactic acid bacteria (rods).
In the presence of the enzyme formate dehydrogenase (FDH), the formic acid created in this reaction is quantitatively oxidized to bicarbonate by nicotinamide adenine dinucleotide (NAD):
HCOO- + NAD+ + H2O \(^{\underrightarrow{FDH}}\) HCO3- + NADH + H+
The amount of NADH formed during the reaction is equivalent to the amount of formic acid and can be determined photometrically based on its absorbance at 334, 340 or 365 nm.
Oxalic acid (oxalate) is transformed into formic acid and CO2 in this reaction catalyzed by the enzyme oxalate decarboxylase (Ox-DC):
Oxalic acid \(^{\underrightarrow{Ox-DC}}\) formic acid + CO2
The quantity of NADH produced during the reaction is equivalent to the amount of formic acid and is determined photometrically owing to its absorption at 334, 340 or 365 nm. In preparation for this test, the free formic acid present in the solution is determined along with the oxalic acid. Each are accounted for in the blank.