Water intended for use as an ingredient in the production of beer (brewing liquor) or other foods
Mercury is reduced by sodium tetrahydroborate to its elemental form by allowing it to flow over a precious metal (e.g., a gold-platinum mesh) with the evolving hydrogen along with the assistance of an inert gas. By rapidly heating the adsorbent, the mercury is released again. It is transferred into a cuvette using a carrier gas where the absorbance is measured.
This method is described as a cold vapor technique.
This method describes how the protein content in adjuncts is determined.
This method describes how the protein content in adjuncts is determined.
Prior to storage, the moisture content of barley must be determined.
The electrical capacitance of a whole, unground grain sample is measured. The apparatus contains three sensors:
Capacitance
The moisture present in a sample absorbs the electrical energy between the walls of the sample container. The electrical signal or the “capacity” increases with higher moisture contents of the sample and with larger sample sizes.
Oscillating weight balance
The oscillating weight balance measures the frequency to determine the mass.
Temperature correction
The capacitance of the sample rises with the temperature. A Thermistor temperature sensor is built into the sample container. The microprocessor automatically corrects for the moisture content.
The nitrogen/raw protein content of barley intended for the production of brewing malt must be determined in advance.
Reflectance spectroscopy in the near infrared spectral range (NIR) is employed as a physical method for the determination of substances found in grain. This method is based on the fact that different substances, e.g., proteins, in wavelengths ranging from approximately 800 to 2500 nm possess characteristic absorbance and reflection spectra.
Light of a defined wavelength is directed towards the (finely ground) sample in a measurement chamber and is reflected diffusely back to a detector, which measures the intensity of the reflected light. On the basis of the absorbance measured, an integrated computer calculates the protein content of the sample. In order to be able to perform these calculations, the NIR spectrometer must be specifically calibrated for each product (e.g., barley, wheat, barley malt, wheat malt) as well as for each constituent (in this case, protein). The calibration is carried out with data gathered from the absorbance of spectra from reference substances. The protein content of individual samples is determined chemically using a reference method, for example, with the Kjeldahl method and are then correlated with the respective spectral data. Through comparison of the spectra from the analysis sample with the reference sample used in the calibration, the protein content is determined. Since seasonal differences in barley kernels from year to year make it necessary to modify the spectral data so that they match the chemically determined data, calibration must be monitored and adjusted accordingly. Normally, the manufacturer supplies a standard calibration reference with the device.
The primary advantages offered by this method are the speed with which samples are analyzed (< 1 min per sample) and the fact that no chemicals are necessary. Grinding the sample at a defined setting prior to the analysis may be required; however, it is not necessary to weigh the sample. With the latest generation of NIR devices, samples no longer need to be ground. The accuracy of the measured values is dependent upon the quality of the calibration. If analysis is performed carefully, standard deviations of 0.1 % are attainable.
The nitrogen/raw protein content of barley intended for the production of brewing malt must be determined in advance.
In contrast to the NIR method, the more recently developed NIT method measures the light passing through the samples. This technique requires no pretreatment of the samples, thus eliminating a major source of error. The large sample size, approx. 500 g, makes highly precise measurements possible. Measurements are usually made in the wavelength range of 570−1100 nm.
Calibration and the calculations for determining the amounts of the various constituents are both performed in the same way as in the NIR method. Special software for personal computers can be employed to create the calibration data, which uses the data structure generated and stored in the NIT device as a basis for the calculations. The advantages offered by this method are the rapidity of the analysis (approx. 45 s per sample) and the absence of chemicals.