Some standard content:
GB/T4928—2001
This standard is a revision of GB/T4928—1991 "Beer Test Method". The main differences between this standard and the original standard GB/T4928—1991 are as follows: 1. The name of the standard is changed from beer test method to beer analysis method. 2. The "inverted cup method" is deleted for sample preparation (removal of carbon dioxide or degassing). The shaking degassing method recommended by the American Society of Brewing Chemists (ASBC) is changed to non-equivalent and used as the first method; the instrumental method of ultrasonic or magnetic stirring degassing is used as the second method. 3. The inspection method of net content is added.
4. Sensory evaluation is included in the text of the standard.
5. For the determination of chromaticity, the provision that a digital display colorimeter can be used is added. 6. For the determination of alcohol content, the first method (density bottle method) adds the volumetric method and the retention weight method; the third method automatic instrumental analysis method is added. 7. For the determination of original wort concentration, the second method automatic instrumental analysis method is added. 8. For the determination of total acid, when the total acid is measured by potentiometric titration, the pH indicating the end point is changed from 9.0 to 8.2; the second method, the indicator titration method, is added.
9. For the determination of carbon dioxide, in the first method (reference method), the sample temperature is changed from 5℃15℃ to 0℃～5℃; in the second method (pressure method), the determination and calculation method of the "headspace volume" of canned wine (aluminum easy-open two-piece can) is added. 10. For the determination of diacetyl, the gas chromatography method is added, but it is placed in Appendix C for reference by enterprises. 11. Two formulas for calculating the true (actual) fermentation degree are added. 12. The analytical method for distinguishing cooked, raw and fresh beer is added. 13. The analytical methods of some indicators that production enterprises need to control by themselves are listed as Appendix C for reference by enterprises. Appendix A and Appendix B of this standard are both standard appendices, and Appendix C is a reminder appendix. This standard will replace GB/T4928-1991 from the date of implementation. This standard was first issued in 1985. The first revision was in 1991. The second revision was in 2001. This standard was proposed by China National Light Industry Federation. This standard is under the jurisdiction of National Food Fermentation Standardization Center. The drafting units of this standard are: China Food Fermentation Industry Research Institute, Tsingtao Brewery Co., Ltd., Beijing Yanjing Brewery Co., Ltd., Shenzhen Kingway Brewery Co., Ltd.
The main drafters of this standard are: Kang Yongpu, Guo Xinguang, Li Aiguo, Lin Zhiping, Li Jianhua. 1
1 Scope
National Standard of the People's Republic of China
Methods for analysis of beer
Methods for analysis of beer This standard specifies the basic principles and methods for beer analysis. This standard is applicable to the analysis of various types of beer. 2 Referenced standards
GB/T4928—2001
Replaces GB/T4928—1991
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard was published, the versions shown were valid. All standards are subject to revision. Parties using this standard should explore the possibility of using the latest version of the following standards. GB/T601—1988
3 Preparation of standard solutions for titration analysis (volume analysis) of chemical reagents GB/T602—1988
8 Preparation of standard solutions for determination of impurities in chemical reagents GB/T603-—1988
3 Preparation of preparations and products used in chemical reagent test methods GB/T1250—1989
Methods for expressing and determining limit values GB4789.2—1994
GB4789.3—1994
GB 4789.4—1994
GB4789.5—1994
GB4789.10—1994
GB 4789.11—1994
GB4789.25—1994
Food Hygiene Microbiological Examination
Determination of Total Colony Count
Food Hygiene Microbiological Examination Determination of Coliform Group Food Hygiene Microbiological Examination
Food Hygiene Microbiological Examination
Food Hygiene Microbiological Examination
Food Hygiene Microbiological Examination
Food Hygiene Microbiological Examination
GB4927—2001
GB/T5009.12—1996
GB/T5009.34——1996
GB/T6682—1992
GB/T 8170—1987
Determination of lead in food
Salmonella test
Shigella test
Staphylococcus aureus test
Hemolytic streptococcus test
Wine test
Determination of sulfite in food
Specifications and test methods for water for analytical laboratories (neqISO3696:1987) Numerical rounding rules
GB/T1386 8—1992
Sensory analysis General guidelines for establishing sensory analysis laboratories (egvISO8589:1988) GB/T14195—1993
3 General principles
Sensory analysis Selection and training Guidelines for selecting sensory analysis evaluators 3.1 The various analytical instruments used in this standard (such as analytical balances, spectrophotometers, etc.) should be calibrated regularly; the density bottles, pipettes, volumetric flasks and other instruments used should be calibrated regularly according to relevant calibration procedures. 3.2 The "instruments" in this method are the instruments specifically required for analysis, and general laboratory routine instruments are no longer listed. 3.3 The water used in this method, unless otherwise specified, meets the requirements of grade 3 (including grade 3) or above water specifications in GB/T6682. 3.4 The reagents used in this method, unless otherwise specified, are analytically pure (AR). Approved by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China on December 4, 20012
Implementation on January 1, 2003
GB/T4928—2001
3.5 The "solution" in this method refers to aqueous solution when the solvent is not specified. 3.6 The significant figures in this method indicate the accuracy required to be achieved when aspirating or weighing. 3.7 When there are two or more analytical methods for the same test item, the first method is the arbitration method. 3.8 The calculation and selection of data shall comply with GB/T8170. The method for expressing and determining the limit values of the test results shall be determined in accordance with the rounded value comparison method in 5.2 of GB/T1250—1989. 3.9 When measuring samples, parallel tests must be carried out and the results shall be reported as the average of the two measured data. The significant figures shall be consistent with the technical requirements.
4 Negative deviation of net content
4.1 Method 1 Gravimetric method
4.1.1 Instruments
4.1.1.1 Electronic balance: sensitivity 0.01g. 4.1.1.2 Platform scale.
4.1.1.3 Constant temperature water bath: accuracy ±0.5℃. 4.1.2 Analysis steps
4.1.2.1 Determination of beer in bottles and cans (aluminum two-piece cans with easy-open lids) a) Place the beer in bottles and cans (aluminum two-piece cans with easy-open lids) in a constant temperature water bath at (20±0.5)℃ for 30 minutes. Take it out, wipe off the water on the outer wall of the bottle (or can), and weigh the mass of the whole bottle (or can) of beer (m1) with an electronic balance. Open the bottle cap (or can lid), pour out the wine, rinse the bottle (or can) with tap water until there is no foam, dry it, and weigh the mass of "empty bottle + bottle cap" (or "empty can + lid") (m2). b) Determination of relative density of wine
Same as 9.1.3.1.
c) Expression of analysis results
The density of wine (at 20℃/4℃) is calculated according to formula (1). p=0.9970×d20+0.0012
Where: p——density of wine, g/mL; 0.9970——difference between the density of distilled water and dry air at 20℃, g/mL; a2—relative density of wine and redistilled water at 20℃; 0.0012-
density of dry air at 20℃ and 1013.25hPa, g/mL. The net content of the sample is calculated according to formula (2).
X = mi m2
- Net content (net capacity) of the sample, mL Wherein. X-
The mass of the whole bottle (or whole can) of wine, g;
The mass of "empty bottle + bottle cap" or "empty can + open cap", g; p-The density of the wine, g/mL.
4.1.2.2 Barrel beer
Weigh with a platform scale, and the rest of the steps are the same as 4.1.2.1.a, 4.1.2.1.b, 4.1.2.1.c. 4.2 Second method Volumetric method
4.2.1 Apparatus
4.2.1.1 Measuring cylinder.
4.2.1.2 Glass pencil (or marker). 4.2.2 Analysis steps
(1)
Place the bottled beer sample in a water bath at (20±0.5)℃ for 30 minutes. Take it out, wipe off the water on the outer wall of the bottle, and use a glass pencil to draw a thin line on the surface of the beer. Pour out the beer, rinse the bottle with tap water (be careful not to wash off the line) until there is no foam, wipe off the water on the outer wall of the bottle, accurately fill the bottle with water to the line, and then pour the water into a measuring tube. Measure the volume of water, which is the net content of the bottled beer (expressed in mL or L). 5 Preparation of samples (for physical and chemical analysis) and aseptic sampling (for microbiological testing) 5.1 Preparation of samples
5.1.1 Summary of methods
On the premise of ensuring that the sample is representative and there is no or little loss of alcohol, remove the carbon dioxide gas in the beer sample by shaking, ultrasonic or stirring.
5.1.2 Method 1
Pour about 300mL of the wine sample at a constant temperature of 15℃~20℃ into a 750mL (or 1L) conical flask, cover it with a rubber stopper, shake it gently in a constant temperature room, open the stopper to release gas (there will be a "bang" sound at the beginning), and cover it with a stopper. Repeat the operation until no gas escapes, and filter it with a single layer of medium-speed drying filter paper (cover the surface glass on the funnel).
5.1.3 Method 2
Use ultrasonic or magnetic stirring to remove gas. Transfer about 300mL of the wine sample at a constant temperature of 15℃~20℃ into a bottle with a vent stopper, place it in an ultrasonic water tank (or on a stirrer), and after ultrasonic (or stirring) for a certain period of time, filter it with a single layer of medium-speed drying filter paper (cover the surface glass on the funnel).
Note: The alcohol content determination results should be similar to those of the first method to determine the ultrasonic (or stirring) time. 5.1.4 Sample Storage
Collect the degassed wine sample in a stoppered conical bottle, keep the temperature at (20 ± 0.1)℃, seal and store, and limit use within 2 hours. 5.2 Aseptic sampling of finished wine
5.2.1 When sampling canned beer, first immerse the lid puller part in 75% ethanol for 1 minute, then burn it with fire, then wipe the top of the can with 75% ethanol cotton balls, and burn the residual ethanol with fire (canned wine with a pull-top can can also be sampled from the other end, and the same aseptic treatment). After opening the lid, cover it with sterile blood (or stopper).
5.2.2 When sampling bottled beer, first immerse the bottle cap part in 75% ethanol for 1 minute, then burn the residual ethanol with fire. After opening the lid, burn the bottle mouth with fire, and then cover it with the original lid (or cover it with a sterilized aluminum sheet). 5.2.3 Aseptic sampling of barrels or cans
Pre-sterilize the sampling port of the barrel or can. Then open the valve safely, rinse the sampler or sampling port with beer for 5s10s, and collect the sample in a sterile bottle using aseptic technology. During the sampling process, any opening device or sampling container must be sterilized. 6 Sensory evaluation
6.1 Wine evaluation environment
Establish a sensory analysis laboratory in accordance with GB/T13868. 6.2 Evaluators
Select and train sensory analysis evaluators in accordance with GB/T14195. 6.3 Preparation of wine samples
Code the wine samples as needed and keep them at a constant temperature of 12℃15℃, and inject them into a clean, dry beer evaluation glass at the same height (3cm from the cup mouth) and injection speed.
6.4 Appearance
6.4.1 Transparency
Place the wine sample (or bottled wine sample) in a bright place for observation, and record the transparency, suspended matter and sediment of the wine. 6.4.2 Turbidity
Measure according to Chapter 7.
6.5 Foam
6.5.1 Morphology
GB/T4928—2001
Observe the color, fineness and clinging of the foam with your eyes, and make a record. 6.5.2 Foam persistence
Measure according to Chapter 8.
6.6 Aroma and taste
6.6.1 Aroma
First place the wine evaluation glass filled with the wine sample under the nostrils, smell its aroma, shake the wine glass, and then smell whether there is hop aroma and foreign odor, and make a record.
6.6.2 Taste
Drink an appropriate amount of the wine sample, evaluate it according to the taste characteristics that the wine sample should have, and keep records. 6.7 Judgment
Write comments based on the appearance, foam, aroma and taste characteristics. Make a comprehensive evaluation based on the sensory requirements in GB4927. 6.8 Chroma
6.8.1 Method Summary
Inject the degassed sample into the colorimetric blood of the EBC colorimeter, compare it with the standard EBC color disk, and visually read or automatically display the color of the sample digitally, expressed in EBC color units. 6.8.2 Instrument
EBC colorimeter (or an instrument with equivalent analytical effect): a visual colorimetric disk with 2EBC to 27EBC units or an automatic data processing and display device. wwW.bzxz.Net
6.8.3 Reagents and solutions
Hartong standard solution: Weigh 0.100g potassium dichromate (K2Cr2Or) and 3.500g sodium nitrosylferrocyanide Na2[Fe(CN)sNO)·2H20, dissolve in water and make up to 1000mL, store in a brown bottle, place in the dark for 24h before use. 6.8.4 Analysis steps
6.8.4.1 Calibration of instrument: Inject Hartong solution into 40mm colorimetric blood and measure with a colorimeter. Its standard chromaticity should be 15 EBC units; if 25mm colorimetric III is used, its standard reading is 9.4 EBC. The instrument should be calibrated once a month. 6.8.4.2 Inject the sample (5.1) into 25mm colorimetric blood, then put it in the colorimetric box, compare it with the standard color disk, and read directly when the colors of the two are consistent. Or use an automatic digital display colorimeter to automatically display and print the results. 6.8.5 Expression of analysis results
a) If colorimetric blood of other specifications is used, it is necessary to convert it into the data of 25mm colorimetric blood and report the results. The chromaticity of the sample is calculated according to formula (3):
X=%×25
Wherein, X is the chromaticity of the sample, EBC;
S is the measured chromaticity, EBC;
H is the thickness of the colorimetric III used, mm, and
25 is the thickness converted to the standard colorimetric III, mm. .. (3)
b) When measuring dark and black beer, it is necessary to dilute the beer sample to an appropriate multiple, and then multiply the measurement result by the dilution multiple. The result is expressed to an integer.
6.8.6 Allowable difference
The difference between two measured values of the same sample shall not exceed 0.5EBC when the color is 2EBC~10EBC. When the color is greater than 10EBC, the difference between the parallel measured values of the diluted sample shall not exceed 1EBC. 5
7 Turbidity
7.1 Summary of the method
GB/T4928—2001
Use the Formazin standard turbidity solution to calibrate the turbidity of the beer sample directly and express it in EBC turbidity units.
7.2 Instruments
7.2.1 Turbidimeter: measuring range 0EBC~5EBC, graduation value 0.01EBC. 7.2.2 Conical flask with stopper: 100mL.
7.2.3 Pipette: 25mL.
7.3 Reagents and solutions
7.3.1 10g/Hydrazine sulfate solution: Weigh 1.000g of hydrazine sulfate, dissolve in water and make up to 100mL. Let stand for 4h to completely dissolve. 7.3.2 100g/Hexamethyltetramine solution: Weigh 10.000g of hexamethyltetramine, dissolve in water and make up to 100mL. 7.3.3 Formazin standard turbidity stock solution: Pipette 25.0mL of hexamethyltetramine solution (7.3.2) into a stoppered conical flask, add 25.0mL of sulfuric acid solution (7.3.1) with a pipette while stirring, shake well, cover with stopper, and leave at room temperature for 24h before use. This solution is 1000 EBC units and can remain stable within 2 months. 7.3.4 Formazine standard turbidity working solution: Pipette 0, 0.20, 0.50, 1.00 mL of standard turbidity stock solution (7.3.3) into four 1000 mL volumetric flasks, dilute to scale with water of 0 turbidity, and shake well. The turbidity of the standard turbidity working solution is 0, 0.20, 0.50, 1.00 EBC respectively. The solution should be prepared and used on the same day. 7.4 Analysis steps
7.4.1 Install and debug the instrument according to the manual. Calibrate the turbidity meter with the standard turbidity working solution (7.3.4). 7.4.2 Take the degassed but unfiltered sample prepared in 5.1 and keep it at (20 ± 0.1) Pour the sample of C into the standard cup of the turbidity meter, put it into the turbidity meter for measurement, and read the value directly (this method is the first method, and the measurement should be completed within 5 minutes after the sample is degassed). Or put the whole bottle of wine into the instrument, rotate it for a week, and take the average value (this method is the second method, draw a cross on the bottle cap in advance, rotate it four times 90° manually, read the value, and take the average value of the four readings to report the result).
The result is expressed to two decimal places.
7.5 Allowable difference
The difference between the two measured values of the same sample shall not exceed 10% of the average value. 8 Foam persistence
8.1 First method Instrumental method
8.1.1 Method summary
Throttling foaming is used. Using the conductivity of the foam, using probe electrodes of different lengths, automatically tracking and recording the time required for the foam to decay, that is, the foam persistence.
8.1.2 Instrument
8.1.2.1 Beer foam persistence tester.
8.1.2.2 Brewing cup: inner height 120mm, inner diameter 60mm, wall thickness 2mm, colorless transparent glass. 8.1.2.3 Gas source: liquid carbon dioxide, cylinder pressure P>5MPa, purity 99% (V/V). 8.1.2.4 Constant temperature water bath: accuracy ±0.5℃. 8.1.3 Analysis steps
8.1.3.1 Preparation of sample
a) Place the wine sample (whole bottle or whole can) in a (20±0.5)℃ water bath and keep it at a constant temperature for 30min; b) Clean the brewing cup thoroughly and set aside. 8.1.3.2 Determination
GB/T4928—2001
a) Debug the instrument to the working state according to the instruction manual; b) Adjust the partial pressure of the carbon dioxide cylinder to 0.2MPa. Calibrate the cup height according to the instrument manual; c) Open the sample bottle cap and place the sample on the foamer for foaming according to the instrument manual. The distance between the foam outlet and the bottom of the foam cup is 10mm, and the time for the foam to fill the cup should be 3s to 4s;
d) Quickly place the foam cup filled with foam under the probe of the foam measuring instrument, press the start button, and the instrument will automatically display and record the results. The results are in seconds and expressed to integers. 8.1.4 Allowable difference
The difference between two measured values of the same sample shall not exceed 5% of the average value. 8.2 Second method Stopwatch method
8.2.1 Method summary
Use the visual method to determine the speed at which beer foam disappears, expressed in seconds. 8.2.2 Instrument
8.2.2.1 Stopwatch.
8.2.2.2 Foam cup: Same as 8.1.2.2.
8.2.2.3 Iron stand and iron ring.
8.2.3 Analysis steps
8.2.3.1 Sample preparation
Same as 8.1.3.1.
8.2.3.2 Determination
a) Place the bubble cup on the iron stand base, fix the iron ring 3cm away from the cup mouth, open the bottle cap, immediately place the bottle (or can) mouth on the iron ring, and inject the wine sample into the cup along the center line of the cup at a uniform flow rate until the foam height is level with the cup mouth. At the same time, start the stopwatch; b) Observe the rising of the foam, record the shape of the foam (including color and fineness) and the foam hanging on the cup; c) Record the time from the foam filling the cup to disappearing (exposing 0.05cm2 of the wine surface). Air circulation is strictly prohibited during the test, and the sample bottle should not be shaken before the measurement. The result is measured in seconds and expressed to the integer. 8.2.4 Permissible difference
The difference between two measured values of the same sample shall not exceed 10% of the average value. 9 Alcohol content
9.1 Method 1 Density bottle method
9.1.1 Summary of the method
Use the mass ratio of alcohol-water solution to the same volume of pure water at 20°C to obtain the relative density (expressed as d20). Then, look up the table to obtain the percentage of alcohol content in the sample, that is, the alcohol content, expressed as %(V/V) or %(m/m). 9.1.2 Instruments
9.1.2.1 All-glass distiller: 500mL. 9.1.2.2 Constant temperature water bath: accuracy ±0.1°C. 9.1.2.3 Volumetric flask: 100mL.
9.1.2.4 Pipette: 100mL.
9.1.2.5 Analytical balance, sensitivity 0.1mg. 6 Balance: sensitivity 0.1g.
9.1.2.7 Density bottle with thermometer: 25mL or 50mL. 9.1.3 Analysis steps
9.1.3.1 Volumetric method
a) Distillation
GB/T4928—2001
Use a 100mL volumetric flask to accurately measure 100mL of the sample (5.1) and place it in a distillation flask. Rinse the volumetric flask with 50mL of water three times, add the washing liquid into the distillation flask, add a few glass beads, install a snake-shaped condenser, use the original 100mL volumetric flask to receive the distillate (with an ice bath), slowly heat and distill (the water temperature at the outlet of the condenser must not exceed 20), collect about 96mL of the jar liquid (distillation should be completed within 30min~60min), remove the volumetric flask, adjust the liquid temperature to 20℃, add water to make up the volume, mix well, and set aside. b) Measurement A
Wash, dry, and weigh the density bottle, and repeat the operation until constant weight. Fill a constant-weight density bottle with water that has been boiled and cooled to 15°C, insert a bottle stopper with a thermometer (there should be no bubbles in the bottle), and immediately immerse it in a (20±0.1)°C water bath. Wait until the temperature of the contents reaches 20°C and keep it unchanged for 5 minutes before taking it out. Use filter paper to absorb the water that overflows the branch pipe, immediately cover the small cap, wipe it dry, and weigh it. c) Measurement B
Pour out the water, rinse the density bottle repeatedly with the sample distillate three times, then fill it up, and do the same as measurement A. d) The relative density of the sample distillate (20°C) is calculated according to formula (4). an-
Where: d20—relative density of the sample distillate (20°C); m—mass of the density bottle, g;
m1—mass of the density bottle and water, g
m2—mass of the density bottle and the sample distillate, g. According to the relative density &2, check Appendix A to obtain the alcohol content of the sample distillate, % (V/V), which is the alcohol content of the sample. The result is expressed to two decimal places.
9.1.3.2 Gravimetric method
a) Distillation
(4)
Weigh 100.0 g of the sample (5.1) to an accuracy of 0.1 g, transfer all of it into a 500 mL distillation flask of known mass, add 50 mL of water and a few glass beads, install a serpentine condenser (or a straight condenser with a cooling part not less than 400 mm in length), turn on the cooling water, use a 100 mL volumetric flask of known mass to collect the distillate (with an ice bath), slowly heat and distill (the water temperature at the outlet of the condenser must not exceed 20°C), collect about 96 mL of distillate (the distillation should be completed within 30 min to 60 min), remove the volumetric flask, adjust the liquid temperature to 20°C, then add water to make the mass of the distillate 100.0 g (the total mass at this time is 100.0 g + the mass of the volumetric flask), and mix well (note to save the residual liquid after distillation, which can be used for the actual concentration).
b) Measurement A and Measurement B
Same as 9.1.3.1.b and 9.1.3.1.c
c) Calculation of relative density of sample distillate (20℃) is the same as 9.1.3.1.d.
According to relative density &, check Appendix A and obtain the alcohol content of the sample distillate, % (m/m). This is the alcohol content of the sample. The result is expressed to two decimal places.
9.1.4 Allowable difference
The difference between two measured values of the same sample shall not exceed 1% of the average value. 9.2 Second method Gas chromatography
9.2.1 Method summary
When the sample enters the chromatographic column of the gas chromatograph, ethanol and other components are separated due to different adsorption coefficients in the gas and solid phases. It is identified by hydrogen flame ionization detector, compared with the standard sample, qualitatively determined by retention time, and quantitatively determined by internal standard method. 9.2.2 Instruments
9.2.2.1 Gas chromatograph: equipped with FID detector. 9.2.2.2 Micro syringe: 1μL.
9.2.3 Reagents and solutions
GB/T4928—2001
9.2.3.1 Ethanol standard solution: use ethanol (chromatographic grade) to prepare ethanol standard solutions of 2%, 3%, 4%, 5%, 6%, 7% (V/V). 9.2.3.2 n-Propanol: chromatographic grade, used as internal standard. 9.2.4 Chromatographic column and chromatographic conditions
Chromatographic column (stainless steel or glass): 2m (or other chromatographic columns with equivalent analytical performance); stationary phase: Chromosorb103, 60 mesh 80 mesh; column temperature: 200℃;
vaporization chamber and detector temperature: 240℃;
carrier gas (high purity nitrogen) flow rate: 40mL/min; hydrogen flow rate: 40mL/min
air flow rate: 500mL/min.
The best chromatographic conditions should be selected through experiments according to different instruments to achieve complete separation of ethanol and n-propanol, and the elution time of ethanol should be controlled at 1min, and the best time for n-propanol (internal standard) is 1.6min. 9.2.5 Analysis steps
9.2.5.1 Drawing of working curve: Pipette 10.0mL of ethanol standard solution (9.2.3.1) of different concentrations into 5 10mL volumetric flasks, add 0.50mL of n-propanol (9.2.3.2) respectively, and mix well. Under the above chromatographic conditions, inject 0.3μL, and draw a working curve corresponding to the alcohol content with the ratio of the peak area of the standard sample and the internal standard (or the ratio of the peak height), or establish a corresponding regression equation. Note: The ethanol standard solution used should be prepared and used on the same day, and each concentration should be prepared at least twice, and the average value should be taken for drawing or calculation. 9.2.5.2 Determination of sample: Pipette 10.0mL of sample (5.1) into a 10mL volumetric flask, add 0.5mL of n-propanol (9.2.3.2), and mix well. The following chromatographic analysis operation is the same as 9.2.5.1. 9.2.6 Expression of analysis results
Use the ratio of the ethanol peak area of the sample to the peak area of the internal standard (or the peak height ratio) to check the working curve, or use the regression equation to calculate the alcohol content of the sample, % (V/V).
The result should be expressed to two decimal places.
9.2.7 Tolerance
Same as 9.1.4.
9.3 Method 3 Instrumental method
9.3.1 Summary of the method
After the degassed beer sample is introduced into the SCABA beer automatic analyzer, one path enters the internally assembled "U" shaped oscillating tube density meter to measure its density; the other path enters the alcohol sensor to measure the alcohol content in the beer sample. 9.3.2 Instrument
9.3.2.1SCABA beer automatic analyzer (or an instrument with equivalent analysis effect): alcohol content analysis accuracy 0.02%. 9.3.2.2 Volumetric flask: 1L.
9.3.3 Reagents and solutions
9.3.3.1 96% ethanol.
9.3.3.2 Cleaning solution: Prepare according to the instrument manual. 9.3.3.3 3.5% (m/m) ethanol calibration solution: Measure 46mL of 96% ethanol and add water to make up to 1L. 9.3.3.4 7.0% (m/m) ethanol calibration solution: Measure 91mL of 96% ethanol and add water to make up to 1L. 9.3.4 Analysis steps
9.3.4.1 Install and debug the instrument according to the manual of the automatic beer analyzer. 9.3.4.2 According to the analyzer manual, calibrate the instrument with water, 3.5% (m/m) ethanol standard solution and 7.0% (m/m) ethanol calibration solution in turn.
9.3.4.3 Introduce the sample (5.1) into the beer automatic analyzer for determination. 9
9.3.5 Expression of analysis results
GB/T4928—2001
The instrument automatically prints the alcohol content in % (V/V) or % (m/m). The result is expressed to two decimal places.
9.3.6 Tolerance
Same as 9.1.4.
10 Original wort concentration
10.1 Method summary
Use the density bottle method to measure the true concentration and alcohol content of the beer sample. Calculate the original wort concentration of the beer sample according to the empirical formula. Or use the instrument method to directly and automatically measure, calculate and print the true concentration and original wort concentration of the sample. 10.2 Method 1 Density bottle method
10.2.1 Determination of true concentration
10.2.1.1 Apparatus
Same as 9.1.2.
10.2.1.2 Analytical steps
a) Sample preparation
Cool the residual liquid (in a distillation flask of known weight) after distilling away the alcohol in 9.1.3.2 to 20°C, accurately add water to make the residual liquid 100.0g, and mix. Or use an evaporator III of known mass to weigh 100.0g of the sample (5.1) to the nearest 0.1g, evaporate it on a boiling water bath until it is one third of the original volume, remove it and cool it to 20°C, add water to restore it to the original mass, and mix. b) Determination
Determine the relative density of the residual liquid using a density bottle or a densimeter. Refer to Table B1 in Appendix B to obtain the number of grams of extract in 100g of sample (g/100g). This is the true concentration of the sample, expressed in plato degree (°P) or % (m/m). 10.2.2 Determination of alcohol content
Same as 9.1.3.2.
10.2.3 Expression of analysis results
According to the measured alcohol content and true concentration, calculate the original wort concentration of the sample according to formula (5). X=(AX2.0665±E)X100
100+AX1.0665
Wherein, X is the original wort concentration of the sample, P or [% (m/m); A is the alcohol content of the sample, % (m/m); E is the true concentration of the sample, P or [% (m/m). Or refer to Table B2 in Appendix B and calculate the original wort concentration of the sample according to formula (6). X=2XA+Eb
Where: X is the original wort concentration of the sample, P or [% (m/m)]; A is the alcohol content of the sample, % (m/m); E is the true concentration of the sample, P or [% (m/m)]; b is the correction factor.
The result is expressed to two decimal places.
10.2.4 Allowable difference
The difference between two measured values of the same sample shall not exceed 1% of the average value. 10.3 Method 2 Instrumental method
10.3.1 Instrument
SCABA beer automatic analyzer (or an instrument with equivalent analysis effect): the true concentration analysis accuracy is 0.01%. 10
.***..(5)
******(6）
10.3.2 Analysis steps
GB/T4928—2001
10.3.2.1 Install and debug the instrument according to the manual of the beer automatic analyzer. 10.3.2.2 Operate the instrument according to the manual, automatically inject, measure, calculate and print out the true concentration of the sample and the original wort concentration, expressed in °P or %(m/m).
The result is expressed to two decimal places.
10.3.3 Allowable difference
The difference between two measured values of the same sample shall not exceed 1% of the average value. 11 Total acid
11.1 The first method of potentiometric titration
11.1.1 Summary of the method
Principle of acid-base neutralization. Use sodium hydroxide standard solution to directly titrate the total acid in beer, take pH=8.2 as the potentiometric titration endpoint, and calculate the total acid content in beer based on the volume of sodium hydroxide standard solution consumed. 11.1.2 Instruments
11.1.2.1 Automatic potentiometric titrator: accuracy ±0.02, with electromagnetic stirrer. 11.1.2.2 Constant temperature water bath: accuracy ±0.5℃, with oscillation device. 11.1.3 Reagents and solutions
11.1.3.10.1mol/L sodium hydroxide standard solution: prepared and calibrated according to GB/T601. 11.1.3.2 Standard buffer solution.
11.1.4 Analysis steps
11.1.4.1 Sample preparation
Take about 60mL of sample (5.1) into a 100mL beaker, place it in a (40±0.5)℃ oscillating water bath and keep it at a constant temperature for 30min, take it out, and cool it to room temperature.
11.1.4.2 Determination
a) Install and debug the instrument according to the instrument manual. b) Calibrate the automatic potentiometric titrator with standard buffer solution. Wash the electrode with water and use filter paper to absorb the liquid beads attached to the electrode. c) Pipette 50.0mL of sample (11.1.4.1) into a beaker, insert the electrode, turn on the electromagnetic stirrer, and titrate with 0.1mol/L sodium hydroxide standard solution to pH=8.2 as the end point. Record the volume of sodium hydroxide standard solution consumed. 11.1.5 Expression of analysis results
The total acid content of the sample is calculated according to formula (7).
X-2XcXV
（7）
Wherein: X is the total acid of the sample, mL/100mL (i.e., the number of milliliters of 1 mol/L sodium hydroxide standard solution consumed by 100mL of the sample); c is the concentration of the sodium hydroxide standard solution, mol/L; V is the volume of the sodium hydroxide standard solution consumed, mL; 2 is the coefficient for conversion to 100mL of the sample.
The result should be expressed to two decimal places.
11.1.6 Allowable difference
The difference between two measured values of the same sample shall not exceed 4% of the average value. 11.2 Second method: indicator method
11.2.1 Summary of the method
Acid-base neutralization titration is performed using phenol as an indicator. 11.2.2 Apparatus
11.2.2.1 Conical flask: 250mL.
11.2.2.2 Pipette: 10mL.
11.2.2.3 Burette.
11.2.3 Reagents and solutions
GB/T4928—2001
11.2.3.1 5g/L phenol indicator solution: prepared according to GB/T603; 11.2.3.2 0.1mol/L sodium hydroxide standard solution: prepared and calibrated according to GB/T601. 11.2.4 Analysis steps
Put 100mL of water in a 250mL conical flask and heat to boil for 2min. Then add 10.0mL of sample (5.1) and continue heating for 1min. Control the heating temperature so that it boils again within the last 30s. After 5 minutes of standing, quickly cool the conical flask containing the sample with tap water to room temperature. Add 0.5 mL of phenolic indicator solution and titrate with 0.1 mol/L sodium hydroxide standard solution until it turns light pink as the end point. Record the volume of sodium hydroxide standard solution consumed.
11.2.5 Expression of analysis results
The total acid content of the sample is calculated according to formula (8).
X=-10XcXV
..(8)
Where: X is the total acid content of the sample, mL/100 mL (i.e., the number of milliliters of 1 mol/L sodium hydroxide standard solution consumed by 100 mL of the sample); C
is the concentration of the sodium hydroxide standard solution, mol/L; V is the volume of the sodium hydroxide standard solution consumed, mL; 10 is the coefficient for converting to 100 mL of the sample. The result should be expressed to two decimal places.
11.2.6 Allowable difference
Same as 11.1.6.
12 Carbon dioxide
12.1 Method 1 Reference method
12.1.1 Summary of the method
Fix the carbon dioxide in beer with alkali solution at 0℃～5℃, release it with dilute acid, absorb it with a known amount of barium hydroxide, and titrate the excess barium hydroxide with hydrochloric acid standard solution. Calculate the carbon dioxide content in the sample based on the volume of the consumed hydrochloric acid standard solution. 12.1.2 Apparatus
a) Carbon dioxide collection and determination instrument;
b) Acid burette: 25mL;
c) Measuring cylinder.
12.1.3 Reagents and solutions
12.1.3.1 Carbon dioxide-free distilled water is prepared according to GB/T603. 12.1.3.2 Sodium carbonate: National secondary standard material GBW(E)060023. 12.1.3.3 300g/L sodium hydroxide solution: Weigh 300g sodium hydroxide, dissolve in water, and dilute to 1L. 12.1.3.4 10g/L phenolphthalein indicator solution: Prepare according to GB/T603. 12.1.3.5 0.1mol/L hydrochloric acid standard solution: Prepare and calibrate according to GB/T601. 12.1.3.6 0.055mol/L barium hydroxide solution a) Preparation: Weigh 19.2g barium hydroxide, add 600mL~700mL of carbon dioxide-free distilled water, stir continuously until dissolved, and let stand for 24h. Add 29.2g of sodium chloride, stir for 30min, and dilute to 1000mL with carbon dioxide-free distilled water. After standing and settling, filter into a sealed reagent bottle and store for later use. b) Calibration: Pipette 25.0mL of the above solution into a 150mL conical flask, add 2 drops of phenolphthalein indicator solution, and titrate with 0.1mol/L hydrochloric acid standard solution until it is just colorless as the end point. Record the volume of hydrochloric acid standard solution consumed (the value should be between 27.5mL and 29.5mL. If it exceeds 30mL, the concentration of the sodium hydroxide solution should be readjusted). Store in a well-sealed state (with a soda lime tube on the top of the reagent bottle, 12
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