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Beer Methods​​​

Recommended Beer Degassing Methods and Alternatives Matrix

The degassing of beer is a critical sample-preparation step for many beer analyses. Although multiple options exist for degassing, each has its own advantages and disadvantages, including degassing time, cost, throughput (one sample vs. multiple samples), release of volatiles (can negatively impact volatile measurements), impact on pH, and thoroughness of degassing. Through a student grant funded by the ASBC Technical Committee, a list of degassing techniques has been compiled with advantages and disadvantages for each technique. This information will be extremely valuable for all brewing laboratories.

Recommended Beer Degassing Methods and Alternatives - Comparison Chart

The degassing of beer is a critical sample-preparation step for many beer analyses. Although multiple options exist for degassing, each has its own advantages and disadvantages, including degassing time, cost, throughput (one sample vs. multiple samples), release of volatiles (can negatively impact volatile measurements), impact on pH, and thoroughness of degassing. Through a student grant funded by the ASBC Technical Committee, a list of degassing techniques has been compiled with advantages and disadvantages for each technique. This information will be extremely valuable for all brewing laboratories.

Beer 1. Sampling

Analytical data developed on a sample of beer reflect only the sample obtained. Whether the analysis is to be chemical, physical, or microbiological, the sample must be representative of the lot of beer to be examined. Where microbiological examination is to be made, special precautions must be taken to avoid contamination. This method is used to prepare samples for chemical and physical analyses; to collect samples aseptically from lines, tanks, and finished packages; and to decarbonate beer with a rotary shaker.

Beer 2. Specific Gravity

Specific gravity is the ratio of the density of a substance to that of a standard substance. This method determines the specific gravity of beer with a digital density meter.

Beer 3. Apparent Extract

Apparent extract is a measure of the solids dissolved in a fermenting liquid without correction for ethanol content. This method reports apparent extract, % by wt, to two decimal places.

Beer 4. Alcohol

This method measures beer and distillate volumetrically and gravimetrically, determines alcohol refractometrically, determines ethanol by gas chromatography, alcohol and original gravity by an instrumental method, low alcohol concentrations by an enzymatic method, and alcohol and original extract content by using a relationship of absorbance at near-infrared wavelengths.

Beer 5. Real Extract

From the residue in the distilling flask after determination of alcohol (Beer-4), this method determines real extract by the method corresponding to the one used for alcohol determination.

Beer 6. Calculated Values

This method calculates values for extract of original wort, real degree of fermentation, apparent degree of fermentation, and the carbohydrate content of beer.

Beer 8. Total Acidity as 'Titratable Acidity'​

Total acidity (TA) is defined as the number of acidic protons that the organic acid potentially can donate. It is experimentally determined by measuring the amount of sodium hydroxide required to raise the pH to 8.2, where neutralization of the acids occurs. Note, however, that using this method will not dissociate all of the protons and thus the method is more accurately defined as titratable acidity, which is the measurement of hydrogen ions consumed by titration with a standard base to an end point. Although technically different, titratable acidity is often used as an approximation of total acidity, and thus is generally referred to as TA.

Beer 9. pH (Hydrogen Ion Concentration)

This method reports the pH of beer to the nearest 0.1.

Beer 10. Color

Beer color is an essential component of the overall sensory perception of the product. Color is experimentally obtained by using a spectrophotomer to determine the absorbance or transmittance of the sample. This method determines the color of beer by the spectrophotometric color method, the photometric method, and tristimulus analysis.

Beer 11. Protein

Beer proteins are partially responsible for good foam retention and desirable mouth-feel characteristics, but they are also partially responsible for haze and undesirable bitterness in beer. This method determines the protein content of beer (% by weight) by the Kjeldahl method, by combustion, and by spectrophotometer.

Beer 12. Reducing Sugars (Copper Reducing Substances)

This method determines reducing sugars in beer by the Munson and Walker method and by the Lane-Eynon volumetric method.

Beer 13. Dissolved Carbon Dioxide

This method determines dissolved carbon dioxide in brewery products in tanks, bottles, and cans and is dependent on establishment by agitation of partial gas pressures in the headspace above beer in a container at a particular temperature. The method is considered sufficiently precise for plant control operations. The method also provides procedures for measuring residual carbon dioxide in beer samples containing up to 1.6 volumes of carbon dioxide and for determining dissolved carbon dioxide in beer by an instrumental method using the principle of volume expansion.

Calculator:
True Carbonation Ca​lculator
*Results from the calculator differ from the ASBC CO₂ chart in some cases

Beer 14. Ash 1958

Ash is the beer residue following the incineration of the organic matter. It consists of mineral matter and serves as a measure of the inorganic salts present in the beer prior to incineration. The ash value is a required term in the calculation of the nutritional components calories and carbohydrates. This method reports ash, % by wt, to two decimal places.

Beer 16. End Fermentation (Yeast Fermentable Extract)

End fermentation is the point at which the yeast has assimilated all the fermentable sugars it can into carbon dioxide and alcohol. This method, which reports yeast fermentable extract, %, to one decimal place, is helpful in determining the final gravity of a beer on a bench scale compared to a beer in a fermenting vessel. This allows brewing staff to monitor fermentation on a daily basis or when dealing with new products that have an unknown final gravity.

Beer 18. Iron

Iron in beer can be detrimental to its organoleptic characteristics, stability, and quality. Thus the iron content of beer should be as low as possible. Metallic notes are derived from contamination of beer with metal ions, and metallic odors can also be produced by lipid oxidation. This method determines iron content, mg/L, by colorimetry, by atomic absorption spectrophotometry, and by analysis with ferrozine.

Beer 20. Calcium

Some form of calcium is often added in the brewhouse. Calcium helps to lower the pH of the mash, can improve enzyme activity, reduces oxalate (preventing the formation of beer stone), and increases yeast flocculation. Monitoring calcium concentration in wort and to a lesser extent in beer can be a tool in consistent beer production. This method determines calcium content, mg/L, by analyses with chrome Black T indicator and calcein and by atomic absorption spectrophotometry.

Beer 21. Total Sulfur Dioxide

This method determines total sulfur dioxide content, mg/L, by the p-rosaniline method and by the segmented flow analyzer method.

Beer 22. Foam Collapse Rate and Foam Stability

This method measures the rate of foam collapse by the Sigma value method (modified Carlsberg method) and the foam flashing method.

Beer 23. Bitterness

Reports of the Subcommittee on Determination of Isohumulones in Beer for 1967 and 1968 indicate that bitterness units (BU), as determined by the two techniques described in Method A, express the bitter flavor of beer satisfactorily, regardless of whether the beer was made with fresh or old hops. The European Brewery Convention has adopted the “E.B.C. Bitterness Units,” determined in a similar way, as a uniform method that best expresses the true bitter flavor value of beer. Method B, which was archived but has now been reinstated, and Method C determine iso-a-acids (IAAs). Method B employs solvent extraction, while Method C uses solid-phase extraction for isolating the IAAs from beer. Method D is an automated version of Method A for measuring BU. While the results of the IAA methods are practically identical to those obtained by the BU method for beer brewed with fresh hops, the IAAs of beer brewed with old or poorly stored hops, and with certain special hop extracts, can be significantly lower than the BU figure. ​Method E uses high-performance liquid chromatography (HPLC) for determination of iso-a-acids in wort and degassed beer. Method G specifies an HPLC technique for the simultaneous determination of iso-a-acids (Iso), humulinones (Hum), and a-acids (Alpha) in beer. Method G is not recommended for the analysis of beers containing reduced iso-a-acids (Rho, Tetra, and Hexa).

IAA Calculator​ - Hops are traditionally added during the boil to extract alpha acids that provide the bitter flavor in beer. Brewers are more frequently using a technique of dry-hopping beers to improve the flavor and aroma in the beer. Dry hopping is frequently done in the fermenter or cask. This process does not add any bitterness to the beer because they have not been boiled in the kettle and the hop acids have not been isomerized. So in effect the dry hopping does not add to the bitterness of the beer. When analyzing a dry hopped beer the possibility of the ultraviolet-absorbing extraneous substances is greater in the BU methods than in the IAA method. The current IBU method overestimates the bitterness in dry hopped beers. To account for this a calculator has been employed to estimate the IAA portion of the IBU result when analyzing dry-hopped beers.

Beer 25. Diacetyl​

This method determines diacetyl content, mg/L, by the broad spectrum method for VDK, the micro dimethyl glyoxime method, and the gas chromatographic method.

Calculator:
VDK Calculator​*
*​For use with the method Beer 25. Spectrophotometric determination of total VDK by distillation and α-naphthol creatine reaction​

Beer 26. Formazin Turbidity Standards

The clarity of beer, or freedom from turbidity, is an important property. Whether turbidity is present because of processing factors or as a result of aging and/or chilling of the packaged product, a means for its measurement as related to a reproducible reference turbidity is a requisite for consistent measurement and reporting of results. In collaborative studies, formazin turbidity standards have proved to provide such a reference scale. This method permits the reporting of beer turbidity in terms of formazin turbidity units.

Beer 27. Physical Stability

The availability of formazin turbidity standards (Beer-26) and of modern instrumentation permits the quantitative measurement of beer turbidity whether it be induced by conditions prevalent in the trade or by “forcing tests” to which the beer may be subjected in the laboratory. Customarily, the beer is chilled before measurement to simulate the practice observed by most purchasers of the product. Results are expressed as formazin turbidity units (FTU). This method measures total haze after chilling (in FTU) and provides a procedure, the accelerated chill-haze test, predictive of the response of packaged beer to inclement conditions in the trade.

Beer 29. Lower Boiling Volatiles in Beer or Ale

Levels of lower boiling volatiles in beer and ale can be determined by several procedures. This method determines the concentrations of ethyl acetate, n-propyl alcohol, i-butyl alcohol, the i-amyl alcohols (composed of i-amyl and active amyl alcohols), and i-amyl acetate in beer or ale by direct injection of a beer sample containing an internal standard onto a gas chromatographic column. The concentration of each of these compounds is obtained by calculating the ratio of the unknown peak to the internal standard and comparing this value to a calibration curve.

Beer 30. Testing for Taste difference Between Two Beers

This method tests for taste differences between two beers with a triangular taste test.

Beer 31. Free Amino Nitrogen (International Method)

The free amino nitrogen content (FAN) of a finished beer reflects primarily the utilization of wort free amino nitrogen during fermentation. Evaluation at various stages of fermentation may also be useful in charting the progressive loss. This method determines the FAN, mg/L, of finished beer.

Beer 32. Viscosity (International Method)

The viscosity of beer can be a useful figure reflecting the content and degradation state of contributory factors, such as ;Β-glucan, derived from wort. This method determines viscosity in centipoise and centistoke units and Pascal seconds.

Beer 33. Caloric Content (Calculated)

This method calculates the caloric content of beer from the alcohol, protein, and carbohydrate contents. The calculation corrects for minerals in real extract of beer and uses the corrected real extract value as a measure of the sum of carbohydrate and protein.

Beer 34. Dissolved Oxygen

This method permits the colorimetric determination of dissolved oxygen in beer by the reaction of oxygen with reduced indigo carmine (disodium indigo disulfonate). It is suitable for use in pale beers containing up to 2 mg/L dissolved oxygen and is recommended for calibration of dissolved oxygen analyzers.

Beer 35. Total Polyphenols (International Method)

Polyphenols, which predominantly originate in malted barley and hops, are implicated in the complex phenomena of beer oxidation and haze formation. In this method, the polyphenols are reacted with ferric iron in alkaline solution, and the red color produced is measured.

Beer 36. Sodium by Atomic Absorption Spectrophotometry (International Method)

Sodium can influence the flavor of the beer at higher concentrations depending on the style. Measurement can verify whether sodium-based cleaning solutions have adulterated wort or beer in the process, whereas pH may not show a shift. This method determines sodium concentration (mg/L) by atomic absorption spectrophotometry.

Beer 37. Potassium by Atomic Absorption Spectrophotometry (International Method)

Potassium can influence the flavor of the beer at higher concentrations depending on the style. Potassium is also critical for yeast growth and carbohydrate metabolism. This method determines potassium concentration (mg/L) by atomic absorption spectrophotometry.

Beer 38. Magnesium and Calcium

This method determines magnesium concentration (mg/L) by atomic absorption spectrophotometry and magnesium and calcium concentrations (mg/L) by sequential titration.

Beer 39. Chloride

Chloride is associated with palate fullness and contributes to the perception of body in a beer. Excessive chloride may inhibit yeast flocculation and promote corrosion of cans. Chloride in beer is determined by titrating the available chloride ion and detecting the presence of excess titrant cation occurring in solution after the end point is reached. Excess Ag+ titrant can be detected by conductivity measurement. This method determines chloride concentration (mg/L) by conductometric titration and by mercurimetric titration.

Beer 40. N-Nitrosamines

This method determines N-nitrosamines levels by distillation (results expressed in μg/L) and by celite adsorption (results expressed as μg/kg).

Beer 41. Total Carbohydrate

These methods are designed to measure the carbohydrate in beer. In Beer-41A, dextrin, the primary carbohydrate present in beer, is hydrolyzed to dextrose by sulfuric acid. Dextrose and phenol, in the presence of sulfuric acid, react further to produce a colored complex that is measured spectrophotometrically. Beer-41B measures the carbohydrate content of beer by high-performance liquid chromatography. Samples are subjected to an ionexchange resin, filtered, and then chromatographed.

Beer 42. Aluminum by Graphite Furnace Atomic Absorption Spectrophotometry

Aluminum packaging containers can impart aluminum to beer under certain circumstances. The aluminum content of beer is determined by atomizing a sample in a graphite furnace and comparing the absorbance of the resulting ground-state atoms to a standard calibration curve.

Beer 43. Anions (Chloride, Phosphate, and Sulfate) by Ion Chromatorgraphy (International Method)

This method utilizes ion chromatography with suppressed conductivity detection to separate and quantitate chloride, phosphate, and sulfate in beer.

Beer 44. Dimethyl Sulfide by Chemiluminescence Detection

Dimethyl sulfide (DMS) is a compound that is typically produced during wort boiling from precursors (e.g., S-methyl methionine) from germination or malting processes. This gas-chromatographic headspace method employs chemiluminescence for the detection of DMS in finished beer.

Beer 45. Elemental Analysis by Inductively Coupled Plasma-Atomic Emission Spectroscopy

This method measures calcium, copper, iron, potassium, magnesium, and sodium in finished or packaged beer 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.

Beer 46. Measurement of Oxidative Resistance in Beer by Electron Paramagnetic Resonance

This method determines the oxidative resistance of beer. Electron paramagnetic resonance (EPR) spectroscopy is used to directly measure free radical production in the beer during a forced oxidation assay. The assay is based on an EPR-spin trapping experiment in which free radicals form covalently bound adducts with the (-phenyl-t-butylnitrone spin trapping reagent. The accumulation of these adducts is detected by EPR during the forced oxidation period and directly reflects the resistance (or lack of resistance) of the beer to oxidation. Two metrics obtained from the assay, lag time and EPR intensity at 150 min (T150) values, can be used to quantitatively assess a beer’s oxidative resistance.

Beer 47. Iso-Alpha-Acids In Beer and Wort by HPLC

This method has been incorporated into Beer-23.

Beer 48. Headspace Gas Chromatography - Flame Ionization Detection Analysis of Beer Volatiles

This method can be used to identify and quantify the generation of volatile organic compounds produced through fermentation. It is designed to measure selected beer volatile compounds in finished beer samples by headspace gas chromatography–flame ionization detection. The selected compounds evaluated through collaborative analysis were chosen to represent different chemical classes (i.e., aldehydes, esters, and alcohols) that are present in beer samples.

Beer 49. Determination of Gluten Using the R5 Competitive ELISA Method IM​

It is imperative that those who are sensitive to gluten can be confident consuming foods that are labeled gluten-free or that are naturally gluten-free. The only process capable of ensuring that a product is 100% gluten-free is to utilize 100% gluten-free grains. For beer that is rendered gluten-free, the competitive R5 ELISA method is capable of detecting hydrolyzed prolamins that remain in beer.

Beer Inclusions: Common Causes of Elevated Turbidity