288 SCIENCE PROGRESS 



The recent investigations into the causes of " strength " in 

 flour, particularly those of Wood carried out at Cambridge, 

 have shown that the quality rather than the absolute quantity 

 of the gluten is the factor of prime importance. Quality in 

 gluten is mainly determined by the proportions of mineral 

 salts present, not in the wheat as a whole but in the actual 

 flour. There is reason to believe that flours differ among 

 themselves both in the absolute amount and in the quantitative 

 composition of their mineral salts. The mere addition of such 

 mineral salts at the moment of doughing flour for bread-making 

 has but a small effect — the necessary minerals must be intro- 

 duced at a far earlier stage, either into the wheat itself by 

 appropriate conditions of culture on the farm or at the time of 

 manufacturing the flour from the wheat. The first alternative 

 cannot yet be realised in practice ; experience has proved, how- 

 ever, that favourable results can be obtained in the second way 

 indicated. There will be but one opinion with regard to the 

 nature of the substances that may with safety be added to flour 

 in this way. It is essential that they should be materials 

 natural to wheat but which Nature, owing possibly to vagaries 

 of climate or of soil, has not provided in sufficient quantity or 

 in the right proportion for the particular crop. The number 

 of possible additions is thus very much restricted. Patents 

 have been taken out for adding a variety of substances to flour 

 most of which are indubitably of improper nature and most of 

 them must have been proposed by persons of the inventor class 

 entirely ignorant of what they were doing; the only substances 

 whose use has been commercially successful are water, malt- 

 extract and certain phosphates. 



Both wheat and flour, far from being materials of constant 

 composition, vary very considerably with regard to the amount 

 of moisture they contain. Flours milled in hot countries or 

 even milled here from the wheats grown in hot countries 

 contain considerably less water than flours milled in England 

 from English wheats. In consequence, flours vary considerably 

 in their water-absorbing capacities. 



Further, both wheat and flour are not inert substances; 

 when they are stored, subtle changes brought about by the 

 agency of enzymes are taking place continually. These changes 

 are known to the miller as conditioning. Water must be present 

 for the enzymic changes to happen and the presence of a little 



