544 SCIENCE PROGRESS 



It was conclusively established that the patents flour ground 

 either from hard or soft wheats which had a somewhat lower 

 amount of protein than the other two samples contained a 

 higher proportion of digestible protein and more available energy 

 than the coarser grades. 



Owing to the fact that they were finely ground the digesti- 

 bility of all these flours was found to be high. When less 

 perfectly ground the bran was still less absorbed and the 

 experiments may therefore be regarded as most conclusive. 

 The bran is not acted upon by the digestive juices owing to the 

 large amount of cellulose present which prevents their access. 



As A. E. Humphries has repeatedly pointed out, wheat is 

 a particularly hardy plant and the husk is the cover provided 

 by nature to protect the food of the baby plant under all 

 sorts of unfavourable conditions. In consequence this husk 

 consists largely of woody fibre able to resist disintegration 

 and obviously indigestible. 



There is also evidence that the presence of bran prevents 

 the assimilation of a certain percentage of the food which 

 would otherwise be digestible. 



It is sometimes contended, generally under the guise of that 

 mystic phrase " the authority of the medical profession," that 

 the presence of bran in bread is valuable on account of the 

 slightly aperient effect that it has. Those who have realised 

 how delicate are the intestinal membranes will hardly accept 

 this policy of " scratching " ; even if bran does not harm, indeed 

 even if it help the healthy grown-up individual, a plea must be 

 raised on behalf of children and invalids. Sufferers from 

 constipation can always turn to wholemeal bread without 

 requiring that the bread supplied to the general public should 

 be spoilt for their selfish ends. 



Bread is in part digested in the mouth, its starch being 

 converted into dextrins by the saliva. For the saliva to be 

 efficient it must be brought into contact with as large a 

 surface of the bread as possible. This takes place most easily 

 with toast and biscuits, which are easily pulverised and 

 saturated with saliva. Obviously the lightest, most vesiculated 

 and driest bread presents a larger surface and is more readily 

 attacked than a closer, moister bread which forms doughy 

 masses more difficult to chew that do not soak up the saliva. 



This explains the well-known indigestibility of new bread 



