The basis for the operation of every laboratory consists of detailed procedures developed, among others, by the European Brewery Convention, which was established by the international organization called The Brewers of Europe, bringing together the largest brewing organizations from the countries of the European Union, as well as Norway, Switzerland and Turkey. The acronym of the English name of the European Brewery Convention (i.e. EBC) was used to designate the unit commonly used in Europe to determine the colour of malt and beer. This organization deals with the technical, technological and scientific aspects of brewing and develops all standards related to the production of malt and beer, including those concerning the parameters of these products and the methods used to measure them. Since all European laboratories use similar procedures and equipment, the results can be compared with one another.
Analysis of the collected grain begins when it arrives at the malt house, although the inspection usually also includes the selection and testing of seed material. Before the grain is accepted, each is tested, and unloading is only possible after the results have been received. An average representative sample of approximately 4 kilograms is taken from every 25 tonnes of grain. Sometimes, even before testing begins, it can be established, for example on the basis of a specific smell, that chemical agents were used to disinfect the grain. The presence of pesticides or live parasites is grounds for rejecting the entire shipment, as insects can infect not only the grain in the silos but also the passageways. If everything is in order, the sample is sent for further analysis.
Basic barley tests include checking moisture, protein content, uniformity and viability. The raw material must meet the requirements specified in the contract, and exceptional grain quality may have a positive impact on its price.
In the case of moisture, considerable differences may occur depending on the weather conditions during harvesting and the conditions in which the barley is stored. Moisture, however, rarely exceeds 14 percent, meaning that bacteria or mould should not develop on the grain. Appropriate protein content is an indication of grain quality. Checking its uniformity is also used to assess the quality of the delivered grain. For this purpose, 100 grams of barley are poured into a device that sifts the sample through increasingly fine sieves for 3 minutes. The grains fall into special compartments depending on their size: above 2.8 mm, from 2.5 to 2.8 mm, from 2.2 to 2.5 mm and below 2.2 mm. Large grains are the most valuable for brewers. Impurities, broken grains and foreign grains, e.g. wheat, are also selected from the sample. Seed viability means its ability to germinate under suitable conditions. To test it, 50 grains are counted from the sample, each is cut lengthwise with a scalpel and treated with a solution which, after some time, colours the embryos pink. After they are counted, the result is given as a percentage.
The tested grain — after being weighed, cleaned and initially separated from impurities — is transferred to designated silos. Grain only acquires its full germination energy over time, which is necessary for proper modification.
After the malting process has been completed, which is also subject to inspection, each batch of malt must also be tested before it is transferred to the appropriate tank. The sample is taken during transport, at regular intervals, using a special automatic sampler. In this way, a homogeneous sample representing the batch can be obtained, which may comprise even hundreds of tonnes of malt.
In addition to measuring moisture, protein and uniformity, as in the case of barley, a range of other tests is carried out, requiring wort to be prepared through the mashing process. Mash vessels are used for the laboratory mashing process. In the process of preparing laboratory (congress) wort, two samples are prepared. First, 50 grams of malt flour, ground in a special mill, are weighed. 200 millilitres of distilled water at a temperature of 46.5 degrees Celsius are added to it and it is placed in the mash vessel. A 30-minute rest at a temperature of 45 degrees Celsius is then applied, after which the temperature is raised to 70 degrees Celsius over 20 minutes and 100 millilitres of distilled water at a temperature of 74-75 degrees Celsius are added. The temperature of 72 degrees Celsius is maintained for one hour, but after just 15 minutes, saccharification is checked using an iodine solution. If the result is positive, the test is repeated every 5 minutes. The wort is then cooled to a temperature of 20 degrees Celsius, topped up with distilled water to obtain a mass of 450 grams, filtered with 100 grams of first wort being returned, the filtration time is measured, the clarity of the wort is determined (clear, opalescent, cloudy), and further measurements are taken. After the wort has been filtered through a membrane filter, its colour is checked in a visual reader (it is then given in the malt specification) and in a spectrophotometer, a device that measures wavelength and converts it into EBC units. The pH of the solution, its viscosity and extract by weight are also checked. The content of free amino nitrogen (free amino nitrogen, FAN) and protein is determined using a special device. The tested malt is then transferred to a silo.
These are only the most important tests. Additional tests are also usually carried out at the customer’s request or on the initiative of the malt house itself. Among other things, the content of dimethyl sulfide precursors (dimethyl sulfide, DMS) and the so-called gushing potential of the malt are checked. Some tests are performed in external laboratories, while others are carried out directly at the customer’s premises if they have their own laboratory available.
Are tests conducted in this way objective and do they provide information about the actual quality of the grain and malt? It seems that, thanks to standardized procedures, it is possible in this case to speak of the maximum achievable level of objectivity. The devices have the appropriate certifications, are calibrated and checked in accordance with the recommendations. Laboratories are subject to mutual verification, and the same samples may be tested by several different institutions. Very often, larger breweries have their own laboratories, which check the purchased raw material randomly or every time. Of course, some tests are less reliable (there are, for example, various methods for determining gushing), and the results from some laboratories show a significant deviation from the average. Therefore, in the event of uncertain results, the tests are repeated several times in internal or external laboratories.
The smaller the malt sample subjected to analysis, the greater the range of results obtained. Consequently, the values provided by the producer for the entire batch may differ from the results obtained in a laboratory for a handful of malt taken from one of many bags. Malt testing must therefore be a rational compromise between attempting to objectively describe its properties and the impossibility of checking every individual grain of barley or malt. Laboratory analysis is the only and, to date, the best tool for determining the quality of barley and malt.