1 64 CONCENTRATED FOOD-STUFFS 



Tested with Fehling's solution the liquid will now show 

 the presence of a reducing sugar (maltose). 



The above process, suitably standardised, is used for determin- 

 ing the relative diastatic power of malt and malt extract. Under 

 standard conditions and with a mucilage of o-i gram starch in 

 ICO C.C., a good extract will cease to give a blue colour with iodine 

 in half an hour at 60° C. 



160. " Diastatic Capacity " of Cereals. 



Under the name " diastatic capacity" Wood expresses 

 a fermentation method of determining the cereal sugar, 

 together with that produced by diastatic action. 



Procedure. — Twenty grams of the flour or finely 

 ground cereal are made into a cream with 20 c.c. of 

 water in a wide-mouthed bottle. Half a gram of yeast 

 is added and well mixed with the liquid. The bottle is 

 then fitted with a stopper through which passes a 

 delivery tube connected with a gas-measuring tube. 

 The bottle is placed in a thermostat at 35° C. and the 

 rate of evolution of carbon dioxide measured. 



Wheat. — The "diastatic capacity" of a strong and a 

 weak wheat flour should be compared. The strength of 

 a wheat is partially measured by the evolution of carbon 

 dioxide, both as to rate and total amount. 



Barley and Malt. — The increased rate of evolution 

 and amount of COg formed from barley after malting 

 can readily be demonstrated by the above process, by 

 comparing the diastatic capacities of barley and malt. 



Rice. 



Rice is composed chiefly of starch, together with about 8 per 

 cent, of protein — rice-gluten. Rice prepared for domestic purposes 

 is highly polished ; the outer portion removed during the process 

 (rice polish) is more nutritious than the grain itself, as it contains 

 most of the "oil" and a higher proportion of proteins. 



