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Wort Methods

Wort 1. Sampling

Wort analysis may be required, or desired, with a variety of worts produced under different conditions. All worts have one thing in common–they are not completely stable and are subject to microbial, physical, and chemical deterioration. Accordingly, cooling rates, clarification procedures, and handling of wort samples must be standardized before comparison of analytical results can be made. This method is used to obtain representative wort samples and to prepare them for chemical and physical analyses.

Wort 2. Specific Gravity

This method measures specific gravity by use of a digital density meter.

Wort 3. Extract

This method reports extract (°Plato) of wort to two decimal places.

Wort 4. Apparent Extract by Hydrometer

This method determines apparent extract with a hydrometer. Determinations are rapid, but slightly less precise, than those of other methods.

Wort 5. Yeast Fermentable Extract

This method determines yeast fermentable extract of wort (%) by use of regular fermentation and by rapid fermentation procedures.

Wort 7. Total Acidity

This method calculates total acidity (as lactic acid) (%).

Wort 8. pH (Hydrogen Ion Concentration)

This method determines the pH (hydrogen ion concentration) of a wort sample.

Wort 9. Wort Color and Sample Preparation

It is necessary that wort be brilliantly clear for color determination. Many plant and laboratory worts are somewhat hazy even after filtration through some types of filter paper and require filter-aid reprocessing to achieve acceptable clarity. This method describes the preparation of wort for color determination by use of Celite and filter paper or disks.

Wort 10. Protein

This method determines protein (% by weight) by the Kjeldahl method and by combustion.

Wort 11. Reducing Sugars (Copper Reducing Substances)

This method determines reducing sugars (% by weight) of wort samples.

Wort 12. Free Amino Nitrogen (International Method)

This method determines free amino nitrogen (FAN) in wort by three methods: the ninhydrin method, segmented flow analysis, and automated discrete analysis. The ninhydrin method can be used to determine the amount of FAN in wort or beer to provide information regarding the quantity of amino nitrogen available to yeast during fermentation, or the quantity of amino nitrogen remaining in beer after fermentation. The method measures amino acids, ammonia, and, to some extent, end-group y-amino nitrogen in peptides and proteins. The method is not specific for a-amino nitrogen since y-aminobutyric acid, which is present in both wort and beer, yields substantial color with ninhydrin. Segmented flow analysis is an automated procedure that can be used for determination of FAN in wort. The FAN concentration is determined based on the ninhydrin reaction. The sample is diluted and mixed with ninhydrin reagent, is incubated for a specified time, and absorbance is determined at 570 nm. The concentration of FAN in the sample is proportional to absorbance at 570 nm. The automated discrete analysis procedure for determination of FAN is based on the reaction of primary amines with o-phthaldialdehyde (OPA). Reactions are performed at 37°C​, and the intensity of absorbance is measured at 340nm.

Wort 13. Viscosity

Viscosity of wort may be measured for a variety of reasons, including comparison of worts from brew to brew, evaluation of processing changes or new malt varieties, and gathering of engineering data required for the design of equipment. The information required, therefore, determines the type of result and the units of reporting. This method calculates absolute or dynamic viscosity (in centipoise units or Pascal-seconds) and kinematic viscosity (in centistokes) using a viscometer and according to the Hoeppler principle by measuring the rolling time of a ball through an inclined glass capillary filled with wort at 20°C.

Wort 14. Fermentable Saccharides by Chromatography

Evaluation of potentially fermentable carbohydrates in wort by gas and liquid chromatography is discussed in this method. Evaluation of brewery wort is complicated by the presence of carbohydrates derived from the mashing of malt and those that may be derived, in varying degree, from adjunct materials, including sugars and syrups.

Wort 15. Magnesium by Atomic Absorption Spectrophotometry

Application of atomic absorption spectrophotometry in the analysis of beer for iron, copper, calcium, sodium, potassium, and magnesium is described in other methods. Its use has been extended to the analysis of wort for magnesium and is described in this method.

Wort 16. Zinc by Atomic Absorption Spectrophotometry (International Method)

Application of atomic absorption spectrophotometry in the analysis of beer for iron, copper, calcium, sodium, potassium, and magnesium is described in other methods. Its use has been extended to the analysis of wort for zinc and is described in this method. This method differs from the analysis of magnesium in wort (Wort-15) in requiring a wort addition standard curve.

Wort 17. Protein in Unhopped Wort by Spectrophotometry

The method provides a relatively simple and rapid means of measuring the soluble protein content of unhopped laboratory wort based on the differing UV absorptions of protein at 215 nm and 225 nm.

Wort 18. β-Glucan in Congress Wort

This method measures the ß-glucan content of congress wort by four techniques. The first exploits the chemistry of the fluorochrome Calcofluor to bind to 1,3- and 1,4-ß-D-glucan. Flow injection analysis is utilized to quantify ß-glucan in congress wort. Segmented flow analysis is used in the second technique. The principle of the methodology involves diluting the wort sample with distilled water and mixing with a Calcofluor reagent, which results in the formation of a fluorescent adduct, cellufluor-ß-glucan (1). The fluorescence intensity of the complex is measured. The fluorescence peak height of the complex is proportional to the concentration of ß-glucan in the wort sample. The third procedure employs a spectrophotometric method to determine ß-glucan content using the GlucaTest Rapid Test kit. The fourth method is an automated discrete analysis procedure that determines ß-glucan content based on the reaction of the sample mixed with Calcofluor reagent. The intensity of the absorbance of the Calcofluor ß-glucan complex is measured.​

Wort 19. Fermentable Carbohydrates by Cation Exchange HPLC

Diluted worts are injected into a high-performance liquid chromatography system. A cation exchange column with water as mobile phase is used to separate the sugars, which are then measured by a refractive index detector. Sugars having a degree of polymerization of 1-3 are quantitatively determined by comparison with aqueous standards containing fructose, glucose, maltose, and maltotriose.

Wort 20. Elemental Analysis by Inductively Coupled Plasma-Atomic Emission Spectroscopy

The method measures magnesium (mg/L) and zinc (g/L) in wort by inductively coupled plasma-atomic emission spectroscopy. The instrument measures the elemental concentrations based on the emission of light for each element as the sample is passed through a plasma.

Wort 21. Thiobarbituric Acid Index 2009

The thiobarbituric acid index method is applicable to both beer and wort. It is a colorimetric assay based on the absorbance of reaction products of thiobarbituric acid with lipid peroxidation products in an acidic medium. Values from the analysis can be used to estimate the level of heat stress a product has undergone during processing (low values = low thermal stress; high values = high thermal stress). By quantifying the effects of heat on wort and beer, a brewer can make adjustments to the process upstream to reduce the level of heat to which the product is exposed during production. Reducing the level of heat stress during beer production is believed to have a positive effect on the flavor stability of the beer produced. This method is particularly useful for brewers who are increasing production, either by brewing at a new location or using different equipment in the brewhouse, and want to maintain consistency of the product.

Wort 22. Wort and Beer Fermentable and Total Carbohydrates by HPLC

Identification and quantification of fermentable and total carbohydrates in samples throughout the brewing process and in final products are determined by high-performance liquid chromatography (HPLC). Samples are introduced into the HPLC system to be chromatographically separated and quantified by the two methods described.

Wort 23. Wort Bitterness

The automated procedure for the determination of international bitterness units (IBUs) in wort is based on the following reaction: the wort sample is acidified with hydrochloric acid and then combined and extracted with iso-octane. The emulsified layer is separated, and absorbance is measured at 275 nm.

Wort 24. International Bitterness Units in Wort by Spectrophotometer

This method has been incorporated into Wort-23.

Wort 25. Rapid Malt Color

The color of malt is determined by preparing an extract using a microwave oven and subsequently measuring the absorbance of the filtered extract at 430 nm using a spectrophotometer.