MALT 163 



until the temperature reaches 60° C. The mash is 

 maintained in this condition until a drop of the liquid 

 gives no blue coloration with iodine solution, ie.^ all 

 the starch has been hydrolysed by the diastase of the 

 malt. The temperature is now raised to 70° C. for a 

 short time and the water in the bath then boiled for five 

 minutes. This step should be arrived at about one 

 hundred minutes after the commencement of the opera- 

 tion. The beaker is cooled and the contents filtered. 

 The residue is well washed and the filtrates and wash- 

 ings made up to 500 c.c. An aliquot part (say 50 c.c.) 

 of the solution is evaporated to dryness in a flat- 

 bottomed weighed dish and the residue weighed. 



The weight of malt extractive matter should average 

 70 per cent, of the weight of malt from which it is derived, 

 or about 235 lbs. per quarter. 



The solution of the malt infusion or " wort " should 

 be of a light colour, the taste peculiar and sweet and the 

 odour pleasant, somewhat like that of new bread. 

 159. {c) Diastase in Malt Extract. — About 100 grams 

 of ground malt are soaked in 100 c.c. water at 35° C for 

 a few hours ; the solid matter is filtered off, and the 

 extract mixed with alcohol until no more precipitate is 

 formed. The latter is filtered off, washed with alcohol, 

 and dried in a desiccator. It consists of impure 

 diastase. 



A thin mucilage of starch is prepared in the usual 

 way and mixed with a little of the diastase, the mixture 

 then being retained at 60° to 65° C. on the water-bath. 

 From time to time a few drops of the solution are 

 removed and tested with iodide solution. As the 

 experiment proceeds the colour struck with iodine will 

 pass from blue to purple, then to reddish brown, and 

 eventually no colour is formed at all. This implies that 

 all the starch and also the erythrodextrin is destroyed. 



