alkodest alcohol determination set - brouwland...extremely accurate determination of the alcohol...

Brouwland Korspelsesteenweg 86 • B-3581 Beverlo - Belgium Tel. +32-(0)11-40.14.08 • Fax +32-(0)11-34.73.59 [email protected] • www.brouwland.com

1. General information

1.1 List of delivered itemsQuantity Description 1 distillation apparatus with ground joint, inclusive

of distillation flask (glass) 1 tube of joint grease (made on the basis of

silicone) 1 boiling stones (glass) 1 plastic bottle (250 ml) for liquid samples 1 glass measuring flask (100 ml) with stopper 1 glass cylinder with plastic base and protective

plastic ring 1 plastic pipette (3 ml) 1 plastic measuring spoon 1 plastic spray-bottle (250 ml) for distilled water 3 hoses (2 m feed hose with ¾” threaded hose

coupling for connection to a water tap, 2 m dis-charge hose, 0.2 m distillate delivery hose)

1 lead ring 1 antifoaming agent (bottle) 1 operating manualPlease check the receipt of any and all ordered articles immediately upon delivery. It is possible that additional articles (cf. “Optional” in our brochure) – e.g. a suitable al-coholmeter or a device for temperature-correction – must be ordered to be able to start work at once.

1.2 Use of the devices in accordance with their intended purpose

ALKODEST 3 is an officially recognized complete analysis system that has been designed both for the speedy and extremely accurate determination of the alcohol content of liqueurs, mash, wine, champagne and other alcoholic liquids and for the determination of the extract content of wine – with neither purpose requiring the use of an electrically operated thermostat nor that of any hazardous chemicals. Measurement is based on distillation = the ref-erence method (separation of alcohol and other substances being contained in a liquid by means of evaporation with subsequent cooling of the transferred vapours, which are thereby condensed into the distillate).

1.3 Further informationThis measuring system can be used without the normally required thermostatic control of the sample volumes at 20 °C, provided that a temperature balance of +/- 2 °C can be maintained between the initial and the final measure-ment of the sample volumes within the required tempera-ture range of 17 °C to 24 °C and that both the initial and the final measurement of the sample are performed at a temperature that corresponds approximately to room temperature.

Alkodest alcohol determination set

11-

10-2

011

/ 01

3.03

7.7

1/10


11-

10-2

011

/ 01

3.03

7.7

2. Assembly and use of the devices

2.1 Distillation apparatus• Put the lead ring on the distillation flask• Slip the ends of the long hoses over the olive-shaped noz-

zles for the feed hose and the discharge hose for cooling water that are provided on the cooler unit.

• Screw the threaded hose coupling of the feed hose for the cooling water supply onto the matching fitting of a water tap. If necessary, install a matching tap fitting.

• Place the end of the discharge hose for the cooling water inside a suitable outlet (e.g. a sink or a similar drain).

• Slip the short hose carefully onto the distillate delivery pipe.

• Place the empty measuring flask for the collection of the distillate under the end of the distillate delivery hose. Push the distillate delivery hose into the measuring flask until the end of the distillate delivery hose is in a position that is just above the adjustment mark of the measuring flask.

• Set up the glass cylinder and adjust it until it is absolutely vertical (crucial!). The place of installation must be free from vibrations, brightly lit and glarefree.

• The glass cylinder must be dry and clean.• Press the glass cylinder into the plastic base. Then slip

the protective plastic ring over the upper end of the glass cylinder.

• Apply a very thin layer of joint grease onto the ground joint of the cooler unit (the grease serves to hermetically seal the joint and must be reapplied whenever it is used up).

• Insert the ground joint of the cooler unit carefully into the ground joint of the distillation flask and press gently to fix it there.

• Put the previously assembled distillation apparatus on (e.g.) an electrically operated hot plate or, alternatively, on the especially efficient and powerful heating plate that is available from KUEBLER as an option.

• Open the cooling water supply and ensure a constant out-flow of tap water (between ½ and ¾ of a litre per minute). CAUTION! As neither the hoses nor their fittings are pressure-proof, proceed with great caution when ever you open the water supply. If the flow rate of the cooling water supply is too high, the resulting high pressure of the water being contained within the feed hose for the cooling water may cause damages by water leakage!

• Lay out the remaining items of the delivery. Keep the silicone hoses, the lead ring and all plastic parts at a safe distance from hot sources of heat and open fire.

2.2 Measurement devices2.2.1 Measuring flask, pipetteAs air bubbles cause errors in volumetric measurement, ut-most care must be taken to eliminate any risk of air bubbles being trapped within the measuring while volumetric measurement is performed.The adjustment mark that is pro-vided on the measuring flask in-dicates the level up to which the flask must be filled with the sample liquid. As the sample liquids “climb” the inner walls of the neck of the measuring flask, the readings for the filling level (sample volume) must be taken at the bottom of the meniscus as is shown in the illustration below. A filling level that is exactly in line with the adjustment mark can normally only

be achieved by using the plastic pipette for an extremely precise proportioning of the liquid volume.Accurate measurement can only be performed if the meas-uring flask is absolutely dry. In addition to that, the meas-uring flask must, whenever it is emptied after the perfor-mance of volumetric measurement, be thoroughly rinsed out with a sufficient quantity of distilled water to eliminate the risk of overlooking any remaining liquid that may pos-sibly adhere to the inner walls of the measuring flask.ADVICE: If the formation of the meniscus within the meas-uring flask is interfered with by foam, use the plastic pipette to easily suck off that foam.

2.2.2 HydrometersThe inscriptions that are imprinted on our hydrometers state the type of reading position (“lower”/”upper”), the appropriate “working liquid”(1) and the reference tempera-ture(2) for the specific hydrometer.The sample liquid to be analysed is poured into a dry glass cylinder that must be absolutely vertical. A hydrometer with built-in thermometer is then immersed into that glass cylinder. Only KUEBLER’s Euro Class III (steps of five) alcoholmeters with built-in thermometers and the special

densimeters with built-in thermometers that have been developed by the firm of KUE-BLER especially for the determination of the density of wine (all of which are available as options) may be used for this analysis.• Hold the hydrometer gently by the top of its stem and submerge all of its body (i.e. all of the thicker part of the hydrometer) in the sample liquid that is contained in the verti-cal glass cylinder.• Turn the hydrometer round until it is in the ideal reading position. Take care to avoid any further rotation of the hydrometer when you release your hold on it. The hydrometer will now slowly sink into the liquid until it is in a position of equilibrium.• Wait 1 or 2 minutes and then gently tap several times with apencil or a similar device on the outside of the glass cylinder(at the level of the thermometric scale of the hy-drometer).(3)• The alcohol content is read from the alcoholmeter scale within the stem of the hydrometer “at the bottom” of the liquid surface. (= “lower” reading – cf. illustration 1), while the scale reading for the density of wine is taken “at the top” of the meniscus. (= “upper” reading – cf. illustration 2)• The viewing direction for taking the read-ings is always horizontal.• The temperature reading of the built-in thermometer must be “Lower” reading taken immediately after the hydrometer reading to permit a sub- “Upper” reading sequent determination of the true alcohol content in accordance with the relevant instructions that are given in section 3.6.

40

30

20

10

0

ill. 1

ill. 2

Adjust-ment mark

Measuring flask

2/10


11-

10-2

011

/ 01

3.03

7.7


• Hydrometers are fragile instruments and must therefore always be handled with great care. Always make sure that they are dry and clean before storing them or using them for measurement. The best way to ensure this is to wipe off the hydrometers – in particular their stems – with alcohol prior to the performance of any measurement. Whenever you use the joint grease, take care to keep it away from the hydrometers, as it is very difficult to remove silicone grease from glass. It is not possible to perform correct hydromet-ric measurement if there is any grease on the stem of the hydrometer that is used for measurement.• The workplace must be free from vibrations, brightly lit and glarefree.• Operators should always be seated while performing measurement by hydrometer.• Officially calibrated hydrometers (ideally with official verification certificates) must be used in all tests requiring extremely high accuracy of measurement (e.g. warranty tests). If the corresponding official verification certificates are available, the high accuracy of the hydrometer readings can be further increased by additionally taking into account the specific measuring errors that are stated in the official verification certificate for each individual hydrometer.To obtain valid hydrometer readings, the temperatures must be strictly kept within the prescribed range, the liquid volumes must be precisely measured and the hydrometer scales must be exactly read.

(1) The “working liquid” is the specific type of sample liquid for which the hydrometer has been designed.(2) Only hydrometer readings that are taken at the pre-scribed reference temperature are valid measuring results. A temperature correction must, therefore, be made in all cases in which hydrometer readings are taken at a tempera-ture (of the measured sample liquid) that differs from the prescribed reference temperature (cf. section 3.6).(3) No waiting time is required if the hydrometers and glass cylinders to be used for measurement are stored in the natural thermostat (filled with water) on the two special plastic storage racks for hydrometers and glass cylinders, respectively, both of which are available as options.

3 Determination of alcohol contentAs it is, in general, not necessary to supervise the distilla-tion process (which takes approx. 15 minutes), other tasks may be performed during that time. A laboratory timer with alarm (available as an option) can be pocketed after set-ting its alarm as required. The sound of the alarm will then indicate not only the end of the distillation process but also the necessity to immediately switch off the heater in order to prevent a burn-in of the extract.

3.1 Apparent alcohol content of thin liqueurs (liqueurs flavoured with herbs and similar liqueurs)

In addition to the articles that are included in our delivery, the following articles (which are available as options) are needed for the performance of this test:

- volumetric glass pipette (capacity 50 ml)- alcoholmeter with adequate measurement range.

• Open the shipping container and very carefully stir up the liqueur to avoid any formation of air bubbles. Then take a sample volume of approx. 70 ml out of that container.

• Pour that liqueur sample into the dry and clean 250 ml plastic bottle for liquid samples and seal that bottle.

• Fill the clean spray-bottle with distilled or softened water and seal that bottle, too.

• Provide for a temperature balance (not necessarily at 20°C) between the liqueur sample and the distilled water, e.g. by leaving the two liquids in the same room for ap-prox. 30 minutes.

• Take the cooler unit off and use a volumetric pipette with a capacity of 50 ml to fill approx. 50 ml of liqueur into the distillation flask. Please observe the detailed instructions for this procedure that are given in section 6.3.

• Use the volumetric pipette again (without prior rinsing) to fill 50 ml of distilled water into the distillation flask.

• Rinse the pipette twice with a small quantity of distilled water. Add the rinse water to the liquid in the distillation flask (use lukewarm distilled water for rinsing if your li-queur sample sticks to the glass of the pipette).

• Put 2 or 3 small boiling stones (reusable) in the distillation flask and add some drops of an antifoaming agent.

• Apply a very thin layer of joint grease onto the ground joint of the cooler unit and press it gently into the ground joint of the distillation flask.

• Rinse out the 100 ml measuring flask with distilled water before you use the plastic pipette to fill in approx. 5 ml of distilled water (= approx. two times the full capacity of the plastic pipette) and finally position the measuring flask under the end of the distillate delivery hose of the cooler unit.

• Turn on the hot plate or any other source of heat to be used and select a temperature setting that ensures that the liquid that is contained in the distillation flask will only be heated up to the temperature at which it just starts to turn to steam, so that the steam that is generated is transferred into the cooler unit. Make sure that the liquid to be analysed can in no case boil over into the measuring flask. Proceed with the distillation process until approx. 4/5 of the liquid volume originally contained in the distil-lation flask are distilled over into the measuring flask. The measuring flask is now filled to a level that leaves at least one fingerbreadth of empty space between the surface of the distillate and the base of the neck of the measuring flask.

• Remove the measuring flask immediately from the cooler unit and put in the stopper.

• Mix the contents of the measuring flask carefully (to be seen from the clearing of the distillate) by moving the measuring flask with the stopper gently in circles and then use the plastic pipette to re-fill the measuring flask pre-cisely up to the level of its 100 ml adjustment mark with distilled water that has previously been brought to the required temperature. Please take note of the information on this procedure that is given in section 2.2.1.

• Pour the contents of the measuring flask into the vertically adjusted dry glass cylinder. Then immerse a dry and clean alcoholmeter into that glass cylinder.

• Take the reading for the apparent alcohol content of the distillate from the built-in scale of the alcoholmeter. Please observe the instructions for taking that reading that are given in section 2.2.2.

3/10


11-

10-2

011

/ 01

3.03

7.7

• Take the temperature reading from the built-in thermo-metric scale of the alcoholmeter immediately after the reading for the apparent alcohol content. WRITE DOWN BOTH THE TEMPERATURE READING AND THE ALCOHOLOMETER READING. THEN DETERMINE THE TRUE ALCOHOL CONTENT (cf. sec-tion 3.6).

• Multiply the true alcohol content of the distillate by two to obtain the alcohol content of the liqueur.

Boiling stones may never be used in overheated liquids!

3.2 Apparent alcohol content of thick liqueurs (liqueurs with egg yolks and similar liqueurs)

In addition to the articles that are included in our delivery, the following articles (which are available as options) are needed for the performance of this test:

- volumetric glass pipette (capacity 50 ml)- anti-caking agent- glass measuring flask (capacity 150 ml) with plastic stopper- alcoholmeter with adequate measurement range.

• Open the shipping container and very carefully stir up the liqueur to avoid any formation of air bubbles. Then take a sample volume of approx. 70 ml out of that container.

• Pour that liqueur sample into the dry and clean 250 ml plastic bottle for liquid samples and seal that bottle.


• Provide for a temperature balance (not necessarily at 20 °C) between the liqueur sample and the distilled water, e.g. by leaving the two liquids in the same room for ap-prox. 30 minutes.

• Take the cooler unit off and use a volumetric pipette with a capacity of 50 ml to fill approx. 50 ml of liqueur into the distillation flask. Please observe the detailed instructions for this procedure that are given in section 6.3.

• Use the volumetric pipette again (without prior rinsing) to fill 100 ml of distilled water into the distillation flask.

• Rinse the pipette twice with a small quantity of distilled water. Add the rinse water to the liquid in the distillation flask (use lukewarm distilled water for rinsing if your li-queur sample sticks to the glass of the pipette).

• Put 2 or 3 small boiling stones (reusable) in the distillation flask and add some drops of an antifoaming agent as well as some drops of an anti-caking agent.



• Turn on the hot plate or any other source of heat to be used and select a temperature setting that ensures that the liquid that is contained in the distillation flask will only be heated up to the temperature at which it just starts

to turn to steam, so that the steam that is generated is transferred into the cooler unit. Make sure that the liquid to be analysed can in no case boil over into the measuring flask. Proceed with the distillation process until approx. 4/5 of the liquid volume originally contained in the distil-lation flask are distilled over into the measuring flask. The measuring flask is now filled to a level that leaves at least one fingerbreadth of empty space between the surface of the distillate and the base of the neck of the measuring flask.



• Pour approx. 100 ml of the liquid that is contained in the measuring flask into the vertically adjusted dry glass cylinder (the glass cylinder is then approximately half full) and immerse a dry and clean alcoholmeter into that glass cylinder.



• Multiply the true alcohol content of the distillate by three to obtain the alcohol content of the liqueur.


3.3 Apparent alcohol content of mashIn addition to the articles that are included in our delivery, the following articles (which are available as options) are needed for the performance of this test:

- glass measuring cylinder (capacity 100 ml)- alcoholmeter with adequate measurement range- anti-caking agent.

As cooler sludge and peels are not only the main reasons for the pulpy (or even pasty) consistency of mash that is contained in a fermenter but also cause by their sedimen-tation in bits and pieces a non-uniform distribution of the substances that are contained in mash, any mash sample to be used for analysis must first be properly pre-treated to correctly reflect the average composition of the mash to be analysed and subsequently diluted.On account of the problems that are regularly encountered in obtaining an average mash sample as well as in measur-ing the volume of mash samples, determination of the al-cohol content is less accurate with mash samples than with other samples.

4/10


11-

10-2

011

/ 01

3.03

7.7

• Stir the mash in the fermenting tub vigorously up and, immediately subsequent to this, take out a manageable sample volume of 1 to 3 litres. If the sample contains large pieces of vegetable matter, so that it seems unlikely that an average sample of a liquid volume of 100 ml can be obtained, or if, on account of the consistency of the sample, it does not seem possible to measure its volume in the glass measuring cylinder, it is recommended to use an electric kitchen mixer to thoroughly chop up the sam-ple. Take utmost care not to mix any air into the sample liquid during that process!

• Fill a liquid volume of approx. 70 ml of properly pre-treat-ed mash into the dry and clean 250 ml plastic bottle for liquid samples and seal that bottle.


• Provide for a temperature balance (not necessarily at 20 °C) between the mash sample and the distilled water, e.g. by leaving the two liquids in the same room for approx. 30 minutes.

• Pour the mash sample into the glass measuring cylinder. The sample volume to be filled into that glass measuring cylinder is 30 ml with pasty mash samples and 50 ml with all other mash samples. Then add tap water until the glass measuring cylinder is filled up to the level of its 100 ml adjustment mark.

• Take the cooler unit off and pour the contents of the glass measuring cylinder into the distillation flask.

• Put 2 or 3 small boiling stones (reusable) in the distillation flask and add some drops of an antifoaming agent as well as some drops of an anti-caking agent.


• Rinse out the 100 ml measuring flask with distilled water before you use the plastic pipette to fill in approx. 5 ml of distilled water (= approx. two times the full capacity of the plastic pipette) and finally position the mea suring flask under the end of the distillate delivery hose of the cooler unit.


• Pour the contents of the measuring flask into the glass measuring cylinder. Fill approx. 2.5 ml of distilled water (= approx. the full capacity of the plastic pipette) into the 100 ml measuring flask to rinse it out and pour the rinse water into the glass measuring cylinder.

• Use the plastic pipette to fill the glass measuring cylinder precisely up to the level of its 100 ml adjustment mark with distilled water that has previously been brought to the required temperature.

• Pour the contents of the glass measuring cylinder into the vertically adjusted dry glass cylinder. Then immerse a dry and clean alcoholmeter into that glass cylinder.


• Take the temperature reading from the built-in thermo-metric scale of the alcoholmeter immediately after the reading for the apparent alcohol content. WRITE DOWN BOTH THE TEMPERATURE READING AND THE ALCOHOLOMETER READING. THEN DETERMINE THE TRUE ALCOHOL CONTENT (cf. section 3.6).

• Multiply the true alcohol content of the distillate by the dilution factor to obtain the alcohol content of the mash.

Pasty mash: dilution factor =3.33 (Glass measuring cylinder was filled with mash up to the level of its 30 ml adjustment mark).Regular mash: dilution factor =2 (Glass measuring cylinder was filled with mash up to the level of its 50 ml adjustment mark).


3.4 Apparent alcohol content of wineIn addition to the articles that are included in our delivery, the following articles (which are available as options) are needed for the performance of this test:

- calcium hydroxide (available at any pharmacist)- alcoholmeter with adequate measurement range.

It is recommended to first determine the density of wine in any analysis of wine that also includes a determination of the extract content.• Pour approx. 150 ml of the wine to be analysed into the

dry and clean 250 plastic bottle for liquid samples and seal that bottle.


• Provide for a temperature balance (not necessarily at 20 °C) between the wine sample and the distilled water, e.g. by leaving the two liquids in the same room for approx. 30 minutes.

• Take the cooler unit off the distillation flask.• Use the 100 ml measuring flask to precisely measure a

sample volume of 100 ml and then fill that liquid volume into the distillation flask. Please observe the instructions in section 2.2.1. If the measuring flask is still moist from rinsing, pre-rinse it first with a small quantity of the same wine sample.

• Rinse the measuring flask twice with a small quantity of distilled water and add the rinse water to the liquid that is contained in the distillation flask.

• Put 2 or 3 small boiling stones (reusable) in the distillation flask and add some drops of an antifoaming agent and a level half-full measuring spoon of calcium hydroxide.


5/10


11-

10-2

011

/ 01

3.03

7.7

6/10







• Take the temperature reading from the built-in thermo-metric scale of the alcoholmeter immediately after the reading for the apparent alcohol content. WRITE DOWN BOTH THE TEMPERATURE READING AND THE ALCOHOLOMETER READING. THEN DETERMINE THE TRUE ALCOHOL CONTENT (cf. section 3.6).


3.5 Apparent alcohol content of champagne and sparkling wine

In addition to the articles that are included in our delivery, the following articles (which are available as options) are needed for the performance of this test:- calcium hydroxide (available at any pharmacist)- volumetric glass pipette (capacity 50 ml)- alcoholmeter with adequate measurement range.

It is recommended to first determine the density of wine in any analysis of champagne that also includes a determina-tion of the extract content.

• Pour approx. 150 ml of the champagne to be analysed into a suitable container that holds two or three times that volume and that can be sealed (e.g. a plastic bottle for beverages with a screw cap). Seal that container.


• Provide for a temperature balance (must not be at 20 °C, but at no less than 17 °C) between the champagne sample and the distilled water, e.g. by leaving the two liquids in the same room for approx. 30 minutes.

• Shake the sample container vigorously to cause the cham-pagne to foam. Carbonic acid is released only very slowly from champagne samples that are taken directly out of a refrigerator. As, however, any densimeter readings that are obtained from champagne samples that are not prop-erly decarbonated are invariably too high, the analysis is bound to be erroneous. The champagne samples should therefore always be warmed up to a temperature between 17 and 20 °C before they are decarbonated.

• As soon as the risk of a foam overflow can be excluded, the cap is cautiously loosened to release the excess pres-sure from the container and then tightened again. This procedure is repeated until there is no longer any build-up of excess pressure within the container. Decarbona-tion can be further improved by pouring the champagne samples upon the end of the shaking procedure through a finely pored paper filter.

• Take the cooler unit off the distillation flask.• Use the 100 ml measuring flask to precisely measure a

sample volume of 100 ml and then fill that liquid volume into the distillation flask. Please observe the instructions in section 2.2.1. If the measuring flask is still moist from rinsing, pre-rinse it first with a small quantity of the same champagne sample.

• Rinse the measuring flask twice with a small quantity of distilled water and add the rinse water to the liquid that is contained in the distillation flask.

• Put 2 or 3 small boiling stones (reusable) in the distillation flask and add some drops of an antifoaming agent and a level half-full measuring spoon of calcium hydroxide.


• Rinse out the 100 ml measuring flask with distilled water before you use the plastic pipette to fill in approx. 5 ml of distilled water (= approx. two times the full capac-ity of the plastic pipette) and finally position the measuring flask under the end of the distillate delivery hose of the cooler unit.

• Turn on the hot plate or any other source of heat to be used and select a temperature setting that ensures that the liquid that is contained in the distillation flask will only be heated up to the temperature at which it just starts to turn to steam, so that the steam that is generated is transferred into the cooler unit. Make sure that the liquid to be analysed can in no case boil over into the measuring flask. Proceed with the distillation process until approx. 4/5 of the liquid volume originally contained in the distil-lation flask are distilled over into the measuring flask. The measuring flask is now filled to a level that leaves at least


11-

10-2

011

/ 01

3.03

7.7

7/10

Y-a

xis

: re

ad

ing

alc

oh

ol

con

ten

t in

% v

ol.

X-axis: measuring temperature °C

one fingerbreadth of empty space between the surface of the distillate and the base of the neck of the measuring flask.







3.6 True alcohol contentThe alcoholmeter readings for the alcohol content are the readings for the apparent alcohol content and must normal-ly be temperature-corrected as the alcoholmeters (hydro-meters) are calibrated for measurement at 20 °C, which, however, is seldom the temperature of the sample liquid at which the hydrometer readings are taken. The required temperature-corrections can be performed by means of the official alcohol table – or, even better, by means of one of KUEBLER’s temperature-correction tables (no. 10 to no.15), which are available as options.

ExampleAn alcoholmeter reading of 42.2 % vol is taken at a tem-perature of 16.5 °C. The appropriate correction value is ob-tained by parallel alignment of two sides of the transparent reading square (which is delivered with our tables) with the axes of coordinates (i.e. X axis and Y axis) that are imprint-ed on table 13 in a position that provides for the one side to intersect the X axis at 16.5 °C, while the other intersects the Y axis at 42.2 % vol. As the corner point of the reading square is now in the correction field with the entry + 1.4, the true alcohol content is:42,2 % vol + 1,4 % vol = 43,6 % vol42.2 % vol + 1.4 % vol = 43.6 % vol.Correction values that are even more accurate can be ob-tained by means of interpolation4), e.g. + 1.38 % vol for the above example.If the corner point of the reading square is exactly on a dividing line between two fields, the correction value to be applied is the average of the two individual values

that are stated in the two fields. Example: If the corner point of the reading square is on the dividing line between the field with the entry + 1.7 and the field with the entry + 1.8, the applicable correction value is + 1.75 %vol.Provided that official verification certificates are avail-able for hydrometers that are used for the performance of extremely accurate measurement, the specific measuring errors that are stated in the official verification certificate of each individual hydrometer may be used for further correc-tion of the measuring results.Temperature corrections can also be performed by means of the special PC program that is available from KUEBLER as an option.

4 Determination of the extract content of wine

In addition to the articles that are included in our delivery, the following articles (which are available as options) are needed for the performance of this test:- test data sheet for wine analysis- KUEBLER’s sets of tables 1 & 2 and 3 & 4, with reading

square- densimeter with built-in thermometer for the determina-

tion of the density of wine.To determine the extract content of a wine sample, both the density of that same wine sample and the density of its alcoholic distillate must be known.The extract content of champagne or sparkling wine is determined in the very same way as that of wine, except that champagne and sparkling wine must be decarbonated before their density can be properly measured. That proce-dure is described in section 3.5 – “Apparent alcohol content of champagne and sparkling wine”.


11-

10-2

011

/ 01

3.03

7.7

4.1 Density of wine (ÇW)at 20 °C• Pour a liquid volume of approx. 130 ml of the wine to be

analysed (whose temperature must be between 15 and 25 °C) into a glass cylinder whose inside must either be dry or pre-rinsed with the wine to be analysed.

• Immerse a dry and clean special KUEBLER densimeter with built-in thermometer into that glass cylinder to take the reading for the density of the wine sample (follow the instructions in section 2.2.2).

• On the basis of that density reading and the reading for the temperature of the sample liquid that is taken at the same time, TABLE 2 is now used (proceed as explained in section 3.6) to determine the true density of the wine sample (ÇW).

The measured wine sample can subsequently be re-used for the determination of the alcohol content (by way of distilla-tion).

4.2 Density of the alcoholic distillate (Ça) at 20 °C

The value for the density of the alcoholic distillate (Ça) can be read from TABLE 3 after the determination of the alcohol content (cf. sections 3.4 and 3.6).

4.3 ExtractSubstitution of the previously determined values for (ÇW) and (Ça) in the formula by TABARIE (see below) yields the value for the “density of the distillation residue after dilution to the liquid volume of the original sample” Çr.The extract content in grams per litre (g/l) that corresponds to Çr can then be read from TABLE 4.

Example:a)The density of a wine sample be determined at 22.5 °C as 1.0135 g/ml.The transparent reading square is put onto TABLE 2 as fol-lows: Vertically across 22.5 °C, horizontally onto 1.0135 g/ml. The corner point of the reading square is inside the cor-rection field with the entry: (3rd and 4th decimals) = + 07;so that: ÇW = 1.0135 g/ml + 0.0007 g/ml = 1.0142 g/ml.

b)The true alcohol content of that same sample be deter-mined as 10.75 % vol. TABLE 3 (start from 10.75 upwards, then continue to the left until you reach the % vol curve) yields the following result: Ça = 0.9838 g/ml.

c)According to TABARIE this means:Çr = ÇW - Ça + 0.9982 g/mlÇr =1.0142 g/ml - 0.9838 g/ml + 0.9982 g/mlÇr =1.0286 g/ml

d) According to TABLE 4, the above value for the “density of the distillation residue after dilution to the liquid volume of the original sample” Çr (= 1.0286 g/ml) corresponds to an extract content of 79.10 g/l.The measuring results may be written down on copies of the test data sheet for wine analysis – both for the purpose of documentation and to facilitate the calculations.

5. Maintenance and cleaning of the devices

5.1 Distillation apparatusIt suffices to rinse the superimposed cooler unit between individual tests with distilled water (clean tap water may be used as a substitute if no distilled water is available) and let that water then drip off.The distillation flask may be cleaned – in particular if the distillation residue is of a syrupy consistency – by means of a bottle brush and water and then thoroughly rinsed out with clean water. A thin film of a dark brownish or black-ish colour that may possibly build up on the bottom surface of the distillation flask in the course of a distillation cycle may sometimes be hard to remove. As that film is of no relevance to the distillation process, it need not be removed prior to the performance of subsequent distillation cycles.Although distillation can be started while the inner surfaces of the glass components are still moist, the outside of the distillation flask must always be absolutely dry before it is heated up.

5.2 Measuring vessels and hydrometersAfter each and every use, the glass cylinders, the measur-ing flask and the plastic pipette must be rinsed out with tap water and then left in the open to dry out completely.Whenever the plastic pipette is soiled to the extent that the liquids no longer run out correctly (e.g. droplets adhere to the inner surface), the pipette must be degreased. The simplest method to achieve this is to put the pipette into a glass cylinder that is filled with alcohol or spirit and leave the pipette in that “bath” over the night. The pipette must subsequently be rinsed out with distilled water before it is dried.Hydrometers must be clean and absolutely free from grease. After each and every use they must first be pre-washed with tap water and then thoroughly rinsed with distilled water before they are finally wiped dry with house-hold cleaning paper or a grease-free clean cloth. Hold the hydrometers only by the top of their stems. Use alcohol to clean them from grease and smears of sweat from your hands before you wipe them dry.Do not use any surface-active cleaning agents, e.g. deter-gents for dishes!

6. Assembly and use of optional devices

6.1 Cardanic standThe use of this cardanic stand eliminates practically all the problems that are normally encountered in the performance of any measurement by means of hydrometers. Owing to the fact that the glass (measuring) cylinder is at all times suspended absolutely vertical, the hydrometer can at no point adhere to the walls of the cylinder while it sinks into the sample liquid. Instead, it will maintain its position in the middle of the liquid surface while it is very slowly immersed into the sample liquid without any rotation, so that there is absolutely no danger of a collision of the hydrometer with the bottom of the cylinder. All of this ensures that the

8/10


11-

10-2

011

/ 01

3.03

7.7

9/10

hydrometer will finally be ideally positioned for an optimal reading of its scale by means of the strongly magnifying reading glass. It is, therefore, highly recommended to use KUEBLER’s cardanic stand whenever measurement is performed by means of hydrometers.

• Adjust the column of the stand until it is vertical.• Slip the O-ring onto the glass cylinder (without base and

ring) - approximately at a right angle to the longitudinal axis of the glass cylinder. To secure a firm hold for the O-ring, both the O-ring and the outside of the glass measur-ing cylinder must be dry.

• Press the black reducing adapter into the inner gimbal of the cardanic suspension.

• Fix the reading glass for the hydrometer readings to the column of the cardanic stand (by pressing the Velcro strip on the reading glass into the matching Velcro strip that is provided on the column of the stand).

• Suspend the glass measuring cylinder in the reducing adapter.

• Set up the cardanic stand near the distillation apparatus in a place that is brightly lit, glarefree and free from vibra-tions.

• Pour the contents of the measuring flask into the glass cylinder.

• Insert a suitable hydrometer into the glass cylinder and perform your measurement.

viewing direction

table stand base

plain washer

column of the stand

reading glass with velcro strip (press into the velcro strip on the column of the stand.

approx. 10 cm

6.2 Natural thermostat (plastic tub filled with water)The natural thermostat (i.e. the plastic tub filled with water) serves to automatically compensate any temperature differ-ences that may possibly exist between the different liquids – viz. sample liquids, distillate, and distilled water -that are used in a particular test. This ensures at the same time that the corresponding volumes will be identical. On account of the insulating properties of air, compensation of tempera-ture differences is significantly faster achieved in a water bath than by simply leaving the items next to each other in the same room for some time.• Place the tub next to the distillation apparatus.• Fix the discharge hose for the tub to the tub. Make sure

that the hose is in its entire length, from the tub outlet to its final drain in a sink or a similar outlet, at no point elevated above the level of the tub outlet.

• Suspend the distillate delivery hose of the distillation ap-paratus in the plastic tub.

• Weight the empty measuring flask for the collection of the distillate with a lead ring and place it under the end of the distillate delivery hose. Push that hose into the measuring flask until its end is in a position that is just above the adjustment mark of the measuring flask.

• Put the end of the cooling water discharge hose of the distillation apparatus in the tub.

• Open the tap for the cooling water supply to the distilla-tion apparatus and fill the tub (up to its overflow) with tap water. Then stop the water supply.

• Place the end of the cooling water discharge hose in a drain (i.e. a sink or a similar outlet).

• Weight each of the plastic bottles containing a sample as well as a bottle with distilled water with a lead ring and store all of those bottles in the water bath – ideally approx. 15 minutes prior to the start of the distillation process.

• Use a floating thermometer to measure the temperature of the water that is contained in the natural thermostat. That temperature should be within a range of 17 to 24 °C. If necessary, use the discharge hose for cooling water to fill additional cooling water into the tub.

• Whenever the distillation apparatus is not used for a lon-ger period of time, tip the tub up to empty it and wipe it dry.

6.3 Volumetric pipetteThe adjustment mark that is provided on any volumetric pipette indicates the level up to which the pipette must be filled. As the sample liquids “climb” the glass walls of the pipette, the readings for the sample volume must be taken at the bottom of the meniscus as is shown in the illustration to your left.

adjustment mark

volumeteric pipette


11-

10-2

011

/ 01

3.03

7.7

Pipettes can only be used for precise proportioning if they are absolutely clean. The following step-by-step procedure must be followed with any volumetric pipette and all volu-metric pipettes that are used with the Alkodest 3:• Immerse the tip of the volumetric pipette into the liquid to

be pipetted.• Use your mouth to suck liquid into the pipette until it is

filled to a level that is slightly above its adjustment mark.• Quickly seal the upper end of the pipette with your finger-

tip.• Wipe off (e.g. by means of a cleansing paper like “Kleen-

ex”) any liquid that adheres to the outside of the bottom part of the pipette.

• Lift your fingertip cautiously up to let additional air flow into the pipette until the filling level of the pipette is low-ered to the level of its adjustment mark.

• Wipe off any remaining liquid that adheres to the tip of the pipette.

• Insert the tip of the pipette into the receiving vessel and blow out the contents of the pipette.

• Make sure to wipe off any liquid that adheres to the out-side of the pipette into the receiving vessel.

• Suck distilled water into the pipette until it is filled to capacity. Then seal the pipette and shake it gently before you pour its contents into the receiving vessel.

As air bubbles cause errors in volumetric measurement, ut-most care must be taken to eliminate any risk of air bubbles being trapped within the measuring vessel while volumetric measurement is performed.Never use your mouth to suck in any liquids for pipetting that are injurious to human health!Rinse the volumetric pipette after use with distilled or deionised water. Dry the pipette by sucking air through it (e.g. by means of a water jet air pump) while you perform your measurement. No drying is required if the pipette is rinsed two or three times with an adequate quantity of the liquid to be analysed before a sample is taken.Whenever a pipette is soiled to the extent that the liquids no longer run out as steadily as required (e.g. droplets ad-here to its inner surface), the pipette must be degreased.This is achieved by filling the pipette – whose bottom open-ing must be sealed by means of a stopper – with alcohol or spirit and leaving that cleaning agent in the pipette over the night.

Subject to modification!

10/10

alkodest alcohol determination set - brouwland...extremely accurate determination of the alcohol...

Documents