Standard Methods of Analysis II.

STANDARD METHODS OF ANALYSIS – 1922

At the request of the Council of the Institute of Brewing, the Reports of the Malt Analysis Committee, which were adopted by the Council of the Institute on January 23rd, 1906, and September 30th, 1910, respectively, have been submitted to revision by the Standing

Committee on Analysis, and the following is the revised Report:—

COLOURED MALTS AND CARAMEL

Coloured Malts

The Mill
As in the case of pale malts, the Seck or Boby mills should be used in the analysis of brown and crystal malts.

With roasted barleys and malts the fineness of the grinding is not of such importance, and as there is some danger of the colour of the extract of a pale malt being raised if the pale malt is ground in a Seck or Boby mill immediately after the mill has been employed for grinding roasted barley or malt, it is advisable, especially in a busy laboratory, to reserve a mill for black malts. This may quite well be a coffee-mill set close, so as to obtain a fine grist.

We recognise that roasted malts and barleys and brown and crystal malts are not commonly purchased on the basis of the standard quarter of 336 lbs., various weights and measures being employed. For convenience of comparison, however, we recommend that analytical results relating to such malts and barleys should be expressed in terms of pounds per excise standard quarter of 336 lbs.

Methods

Brown and Crystal Malts
Extract.—50 grams of the sample are to be ground in the Seck or Boby mill, set as recommended for pale malts (p. 776). The grist is to be mixed with 300 c.c. of distilled water at 158° F., and, when constant at 150° F., 100 c.c. of cold water malt extract (see Appendix II, p. 786), previously heated to 150° F, are to be added. The mixture is to be kept for one hour at a temperature of 150° F., then cooled to 60° F. and made up to 515 c.c., shaken, filtered, and the specific gravity taken. The necessary correction for the cold water malt extract employed is to be obtained by diluting a volume of 100 c.c. of the malt extract with 300 c.c. of water, the mixture being kept at 150° F. for one hour. It must then be cooled to 60° F., made up to 500 c.c. at 60° F., filtered, and its specific gravity taken.

Colour.—A volume of 20 c.c» of the,above extract, which must be brilliant, is to be diluted to 100 c.c. and the colour read in a 1-inch cell, using a Lovibond tintometer and glasses of the “52” series, under conditions specified for pale malts (p. 777). The colour due to the malt extract is to be neglected.

Roasted Barleys and Malts
Extract.—A little over 50 grams of the sample is to be finely ground in a coffee mill, and of this exactly 50 grams are to be extracted with about 350 c.c. of boiling distilled water, care being taken to avoid balling. The infusion is to be kept in a bath of boiling water for 1 hour, after which it is cooled, made up to a volume of 515 c.c. at 60° F., shaken, filtered, and the specific gravity of the filtrate taken.

Colour.—A volume of 20 c.c. of the above extract is to be diluted to 1,000 c.c. and the colour read in a 1-inch cell, using a Lovibond tintometer and glasses of the “52” series (p. 777).

Caramel
Colour.—10 grams of the sample are to be dissolved in distilled water, and made up to 100 c.c. at 60° F. 10 c.c. of this solution are diluted to a litre, filtered if necessary, and the colour read in a 1-inch cell, using a Lovibond tintometer and glasses of the “52” series under the conditions specified for pale malts (p. 777).

Statement of Results
Results are to be expressed to the nearest first decimal place only, except in the case of colour, which must be recorded to the nearest half unit.

Brown and Crystal Malts
Extract per standard quarter of 336 lbs.

Colour: In a 1-inch cell, “52” series Lovibond (2 per cent, extract).

Roasted Barleys and Malts
Extract per standard quarter of 336 lbs.

Colour: In a 1-inch cell, “52” genes Lovibond (0·2 per cent, extract).

Caramel
Colour: In a 1-inch cell, “52” series Lovibond (0·1 per cent, solution).

Appendix II

Cold Water Malt Extract
The extract is to be prepared from a well modified pale malt of diastatic power 30° to 40° (Lintner) by digestion of the ground malt with three times its weight of distilled water for 1 hour at 60° to 70° F., and subsequent filtration.

For and on behalf of the
Standing Committee on Analysis,
A. CHASTON CHAPMAN, Chairman.