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​Malt Methods

Malt 1. Sampling

The validity of laboratory evaluation of a lot of malt is no better than the validity of the sample received. Precise laboratory analysis of a nonrepresentative sample may indeed, by misinformation, be worse than no analysis at all. This method presents the basic procedures for obtaining representative samples of malt and preparing them for laboratory analysis.

Malt 2. Physical Tests

This method presents a number of physical tests that may be made on malt to assist in characterization and in evaluation of quality. Tests include determination of test weight per bushel, assortment, 1,000-kernel weight, presence of foreign seeds and skinned or broken kernels, mealiness, and length of acrospire.

Malt 3. Moisture

The method determines the moisture content (%) of finished, kilned malt with a moisture content sufficiently low to permit grinding in a malt mill.

Malt 4. Extract

This method determines the extract (% as-is and dry basis) of malt. The procedure is useful not only to evaluate the potential of malt for producing total wort-solubles but also to serve as a predictive means for estimating contribution of malt to such wort properties as fermentable extract, total acidity, pH, color, viscosity, total nitrogen, and free amino nitrogen. Accordingly, conditions attendant on production of such wort are critical and are given in substantial detail in this method.

Malt 6. Diastati​c Power

The diastatic enzymes of malt can be evaluated by any of the four procedures described in this method. The first comprises extraction of the enzymes by malt infusion, followed by reaction of an aliquot of the resulting solution with standard starch substrate under closely controlled conditions of time, temperature, pH, and enzyme-substrate relations. Production of reducing substances (primarily reducing sugars) is measured using a ferricyanide procedure. The second provides a rapid means of measuring malt diastatic power based on absorbance at 415 nm. The third measures diastatic power by automated flow analysis. The fourth determines diastatic power by automated discrete analysis based on the action of a malt infusion on a buffered starch substrate.

Malt 7. Alpha-Amylase

This method measures α-amylase activity in malt by a fixed color and variable time procedure, a fixed time and variable color procedure, ​an automated flow analysis procedure using iodine reagent, an automated flow analysis procedure using ferricyanide reagent, and an automated discrete analysis porcedure using a buffered limit-dextrin substrate.​

Malt 8. Protein (N X 6.25)

This method determines the protein content of malt by two procedures. The first is the Kjeldahl method, which measures total nitrogen in malt that can, after acid digestion, be distilled off as ammonia. If the results are desired as “% protein,” the conventional factor of 6.25 is used to convert nitrogen to protein, notwithstanding the fact that, as barley progresses to malt, to wort, and to beer, “N × 6.25” becomes increasingly less a representation of true protein. The second method measures nitrogen formed during combustion of the sample in pure oxygen (see Barley-7C). Nitrogen values can be converted to protein by multiplying by 6.25.

Malt 9. High-Dried, Caramel, and Black Malts (Caramel Extract is International Method)

Caramel, high-dried, and black malts are used in brewing primarily for production of beer with a somewhat darker color than “normal” and that may have a distinctive flavor. This method determines extract in caramel and high-dried malts and moisture and color in all three products.

Malt 10. N-Nitrosamines

This method measures N-nitrosamines in malt (µg/kg) by three procedures: vacuum distillation, celite column extraction, and hot aqueous extraction.

Malt 11. Sulfur Dioxide

This method measures sulfur dioxide (mg/kg) in malt.

Malt 12. Malt Modification by Friability (International Method)

This method determines friability and unmodified malt values, which relate to overall malt modification. Friability analysis involves crushing a sample of malt in a friability instrument and then weighing the portion remaining on its screen. Percent unmodified malt is then determined by further sieving.

Malt 13. Deoxynivalenol by Gas Chromatography

This method measures the level of chemically derivatized deoxynivalenol (DON) by gas chromatography with electron capture detection or by mass spectrometry. It is suitable for measuring DON in both barley and malt.

Malt 14. Dimethyl Sulfide Precursor by Headspace Gas Chromatography

In this method, gas chromatography is used to determine the levels of total and free dimethyl sulfide (DMS) in the headspace of malt extracts. The difference between total and free DMS corresponds to the amount of dimethyl sulfide precursor (DMSP) present in the malt sample.

Malt 15. Grist

This method classifies malt grist from mill grindings by standard and manual sieve analysis.

Malt 16. Lipoxygenase Enzymatic Activity In Malted Barley By Absorbance Method

Lipoxygenase (LOX) is first extracted from malted barley with an acetate buffer. The extracted LOX is combined with an aliquot of linoleic acid. Spectroscopy is utilized to measure the enzymatic activity of LOX, which can be seen as an increase of absorbance at 234 nm.