Display Title

Barley Methods​

Barley 1. Sampling and Grading

Barley is an agricultural commodity, and its sampling, inspection, grading, and certification are regulated by the U.S. Department of Agriculture (USDA). In Canada, the regulatory agency is the Canadian Grain Commission. The USDA outlines in substantial detail the factors to be considered. This method describes the grading process and the sampling of barley so as to obtain a portion that is representative of a lot of grain, a requisite for meaningful laboratory evaluation of the material.

Barley 2. Physical Tests

A number of physical tests may be made on barley to assist in characterization and in evaluation of quality. This method determines variety, test weight per bushel, assortment, 1,000-kernel weight, texture of endosperm, skinned or broken kernels, and weathering and kernel damage.

Barley 3. Germination

The ability of barley to germinate fully and with vigor, which is essential to normal malting practice, is called “germinative energy.” This method evaluates this property and predicts the performance of the grain if introduced into malting at the time the test is made. It also evaluates “germinative capacity,” the viability of the kernels and thus the potential germinative energy at some future date.

Barley 4. Preparation of Sample for Chemical Analysis

Various tests require different amounts of grist. This method is used to obtain samples that are representative and sufficiently fine so that a representative sample from the grist is ensured.

Barley 5. Moisture

Barley moisture is a grading factor, and the method of its determination is prescribed in the U.S. by the U.S. Department of Agriculture and in Canada by the Canadian Grain Commission. This method determines moisture in barley by three procedures: air oven, alternate air oven, and moisture in whole grain by near-infrared spectroscopy.

Barley 6. Extract

Evaluation of barley extract by digesting ground barley with a mixture of enzymes somewhat simulating those that may be formed, or released, during malting may provide supplemental information of predictive value in malting. While results do not correlate very closely with extract yields determined on malt made from the same barley, they are useful for comparing barleys of different lots or varieties. This method determines barley extract, as-is basis, %, and dry basis, %.

Barley 7. Protein

This method is the classical Kjeldahl procedure, in which the total nitrogen in barley is distilled off as ammonia after acid digestion. If the results are expressed as “% protein,” the conventional factor for barley of 6.25 is used to convert nitrogen to protein.

Barley 8. Potential Diastatic Power

A substantial portion of the starch-saccharifying enzyme of barley (Β-amylase) is in bound form. This can be released by digesting with a suspension of proteolytic enzyme, e.g., papain, in a fashion similar to the release in malting by the natural proteolytic enzymes evolving during germination. Diastatic power of malt results from the combined actions on starch of Β-amylase and the dextrinizing enzyme (-amylase produced during germination. However, a sufficiently high percentage of malt diastatic power is attributable to Β-amylase to make an evaluation of this enzyme in barley of some predictive value. This method calculates the potential diastatic power of barley and reports it as diastatic power in degrees to the nearest whole number.

Barley 9. Kernel Brightness (Instrumental)

The intensity of surface discoloration of barley kernels (“staining,” “weathering”) can be evaluated quantitatively by the degree to which light is reflected. Several commercially available instruments have demonstrated the potential for such measurement. The high correlation coefficients between the three instruments tested permit the various scales employed by the individual instruments to be interconverted using the formulas provided in this method.

Barley 10. Barley Pregermination by Fluorescein Dibutyrate (International Method)

This method is designed to detect and measure the level of pregerminated grains in harvested barley. It can be used to check barley for pregermination at receiving stations before it is committed to storage. This method is based on the principle that germination is characterized by the release of enzymes that can be visually identified by staining with a lipase-sensitive fluorochrome. The enzyme activity appears as bright yellow fluorescence when viewed under ultraviolet light.

Barley 11. Deoxynivalenol by Gas Chromatography

Three methods for measuring deoxynivalenol (DON) are detailed. The first method measures the level of chemically derivatized DON by gas chromatography with electron capture detection (GC/ECD) or by mass spectrometry (MS). It is suitable for measuring DON in both barley and malt. Second, the EZ-Tox DON test kit is a rapid enzyme immunoassay that incorporates ready-to-use liquid reagents suitable for the determination of DON in barley, wheat, corn, and other grains. Third, the Charm ROSA DONQ2 quantitative test is an im¬munoreceptor assay utilizing lateral flow technology, and other lateral flow test kits by different manufacturers are available that give similar results, including Neogen Reveal Q+ and Envirologix Quick Scan.

Barley 12. Sprout Damage

This method evaluates sprout damage by two procedures: the Falling Number Method and the Stirring Number Method. α-Amylase is released when barley germinates in the field (preharvest sprouting). The Falling Number Method detects α-amylase activity and is based on the ability of α-amylase to liquefy a starch gel. The level of enzyme is indicated by the falling number (FN), defined as the time in seconds required to stir and allow the stirrer to fall a measured distance through a hot aqueous flour gel undergoing liquefaction. A low FN is indicative of higher levels of α-amylase. Rain damage in barley can cause the germination process to begin with a consequent rise in α-amylase activity. Reaction of α-amylase with endogenous starch in a sample reduces viscosity when heated in excess water, which can be measured by the Stirring Number Method.