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.
Water intended for use as an ingredient in the production of beer (brewing liquor) or other foods
Through the addition of solid calcium carbonate to a water sample followed by constant stirring for a period of time, either part of the salt will dissolve or the water will remain unchanged. By examining the sample prior to and after the addition of calcium carbonate, one can quantitatively determine whether it is lime-aggressive or not.
The definitions of the various types of hardness in water are provided here in addition to their calculations.
Water intended for use as an ingredient in the production of beer (brewing liquor) or other foods
According to DIN 38409 part 6 (January 1986) “hardness” is defined as the calcium and magnesium ion content of a water sample. In particular cases, barium and strontium ions may also contribute to hardness. Even though the term hardness is not a scientific one and in principle is even legally objectionable since no SI unit exists for it, hardness is still indispensable, as it simplifies the terminology. For this reason, the somewhat dated units are still deemed acceptable alongside the current mg/l, mval/l and mmol/l. The unit “Deutscher Grad” (degrees German hardness), 1 °d (in the past, also known as 1°dH) is equivalent (based on CaO) to 0.3566 mval = 0.179 mmol/l: *)
*) SI units recognized in legal and commercial transactions, whereby °d should be expressed in mmol/l
10.00 mg/l CaO = 7.15 mg/l Ca2+ = 0.3566 mval/l
7.19 mg/l MgO = 4.34 mg/l Mg2+ = 0.3566 mval/l
For the unit 1 mval/l, the values shown above are higher by a factor of 2.804 (1/10 of the CaO equivalent weight).
28.04 mg/l CaO = 20.04 mg/l Ca2+ = 2.804 °d
20.15 mg/l MgO = 12.15 mg/l Mg2+ = 2.804 °d
An alkaline earth ion concentration of 1 mg/l corresponds to:
1 mg/l Ca2+ = 0.1399 °d = 0.0499 mval/l hardness
1 mg/l Mg2+ = 0.2306 °d = 0.0822 mval/l hardness
Calcium and magnesium are the principal alkaline earth metal ions found in natural waters.
For certain applications and/or treatment processes, knowing the total hardness is insufficient, since understanding which alkaline earth metals are responsible for it is important (usually calcium or magnesium ions). These cations are also paired with anions, in which case the ions of carbonic acid play a significant role (carbonate and hydrogen carbonate ions).
The subgroups of hardness can be characterized as follows:
Calcium or lime hardness (Ca-H):
The portion of the water hardness caused by calcium ions.
Magnesium or magnesia hardness (Mg-H):
The portion of the water hardness caused by magnesium ions.
Total hardness (TH):
This term encompasses the sum of the individual types of hardness (Ca-H + Mg-H).
Carbonate hardness (CH):
The carbonate hardness corresponds to the concentration of alkaline earth metal ions equivalent to the hydrogen carbonate and carbonate ions present in the water. These ions are measured in mval/l through determination of the m value. Water that does not require acid for neutralization to reach the m value possesses no carbonate hardness (pH < 4.3). The m value corresponds to the carbonate hardness in mval/l. This is true as long as this value does not exceed the total hardness in mval/l, since by definition the carbonate hardness cannot exceed the total hardness. Water with an m value that exceeds the total hardness in mval/l is called “sodium alkaline” since it contains sodium. In selecting the treatment process, it is advisable to differentiate between calcium and magnesium carbonate hardness (Ca-CH and Mg-CH).
Non-carbonate hardness (NCH):
This is defined as the difference between total hardness and the carbonate hardness and thus, as that portion of calcium and magnesium ions for which no equivalent bicarbonate and carbonate ions are present in the water, but for which an equivalent quantity of other ions exist (e.g., hydroxide, chloride, sulfate, nitrate, phosphate, silicate, humate). Waters, whose m value is ≥ TH (mval/l), do not exhibit non-carbonate hardness.
Required analysis data:
calcium ion content in mg/l or mval/l
magnesium ion content in mg/l or mval/l
acid required to reach the m value in mval/l
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.
Boiler water for use in the production of beer and other foods
Analogous to the p and m values obtained in the determination of acid capacity (pH 8.2 and 4.3), this analysis is performed according to W-000.13.031 Acid Consumption (Alkalinity, p-Value and m-Value)/Acid Capacity to pH of 8.2 and/or 4.3 for Water. The alkaline capacity of the boiler water is determined through titration of the sample with 0.1 N sodium hydroxide (instead of hydrochloric acid) to a pH of 4.3 and/or 8.2.
The method describes the legal requirements for mineral, spring and table water.
Mineral, spring and table waters that are to be put on the market.
In EU member states, Council Directive 80/777/EEC on the approximation of the laws of the Member States relating to the exploitation and marketing of natural mineral waters of 15 July 1980 became the basis for the implementation of existing laws at national level (current version dated 18 June 2009: Directive 2009/54/EC).
Article 5 of Directive 2009/54/EC regulates the requirements for mineral water both at the source and in the bottled water.
Paragraph 1 of Article 5 specifies the permitted total colony counts. At source, the total colony count (CFU) must not exceed 20 CFU/ml at 20 °C to 22 °C/72 h and 5 CFU/ml at 37 °C/24 h. These values are to be understood as GUIDE figures [3].
After bottling, LIMITS apply to both colony counts if the total bacterial counts were analysed within 12 hours of bottling. The maximum permitted concentrations are defined as 100 CFU/ml at 20 °C to 22 °C/72 h and 20 CFU/ml at 37 °C/24 h [3].
No limit values are set for the total colony count for the marketing stage in paragraph 3 of Article 5. This takes account of the fact that mineral water is not sterile and that, under appropriate conditions, there may be an increase in microorganisms (e. g . storage conditions in retail outlets or at the consumer's premises), but this may only originate from the natural microbial flora it had at source. In addition, the mineral water must be free from organoleptic defects [3].
Paragraph 2 of Article 5 defines the requirement that mineral water must be free from parasites and pathogenic microorganisms [3]. This is considered to be fulfilled if Escherichia coli, coliforms, faecal streptococci and Pseudomonas aeruginosa cannot be detected in a sample volume of at least 250 ml and sporulated sulphite-reducing anaerobes cannot be detected in any 50 ml sample examined ("indicator principle").
Annex I Section II Number 1.3. sets out the criteria for microbiological tests at the source (quantitative determinations of indicator bacteria, sample quantities, incubation temperatures, incubation times). In the author's view, these criteria also apply to the filling of mineral water, even if this is not explicitly stated.
The EU Directive does not specify (apart from quantitative determinations) which methods should be used for carrying out microbiological tests. This is therefore left to the discretion of each Member State within the framework of national implementation.
In Germany, the "Table Water Ordinance" of 12 November 1934 was replaced by the implementation of the EU Directive with the German Mineral and Table Water ordinance (MTVO) of 1 August 1984 (current version of 5 July 2017).
It should be noted that the German implementation deviates from the EU directive in some respects. The "quantitative determination" requirement is not fulfilled in the MTVO or in the corresponding chapter in the collection of official test methods (Section 64 of the German Food and Feed Code LFGB, L59.00) for "indicator organisms". Qualitative methods are listed here.
There is a further deviation in the incubation time for the total colony count of 20 °C to 22 °C. The EU directive specifies 72 hours [3], while the MTVO and § 64 LFGB specify 48 hours [1, 2].
There are also differences between the two German regulations with regard to the higher incubation temperature. The MTVO lists 37 °C ± 1 °C [1], whereas § 64 LFGB lists 36 °C ± 1 °C [2]. From the author's point of view, this deviation has no foreseeable significant relevance to the growth behaviour of the bacteria.
In the following explanations of the test methods, only one of the two temperatures is used, namely 37 °C ± 1 °C (however, 36 °C ± 1 C can also be used in daily laboratory practice).