136 



KNOWLEDGE. 



April, 1913. 



It was with considerable surprise that 1-71 per cent, 

 of Ether-extract was taken from the Mummy Wheat 

 when compared with 2-51 per cent, from an English 

 wheat harvested in 1911. The figures have, how- 

 ever, been carefully checked and confirmed. 



Wheat oil very rapidly undergoes decomposition 

 on exposure to air, De Negri finding that a sample 

 after being kept for one year contained nearly half 

 its weight of free fatty acid calculated as Oleic acid. 



Balland (Compt. Rend. 190.5, CXXXVT, 724) 

 obtained some sixteen parts of Ether-soluble fatty 

 acids with eighty-four parts of true oil from one 

 hundred parts of fatty matter extracted by Ether 

 from freshly-milled flour, whilst an older sample of 

 flour gave fatty matters containing only eighteen 

 per cent, of true oil with eighty-two per cent, of 

 mixed fatty acids. 



It is apparent, therefore, that quite a large propor- 

 tion of the fatty acids obtained from wheat oil is 

 soluble in Ether, a fact which accounts for the 

 unexpectedly high figures obtained for fatty matter 

 extracted by Ether from the Mummy Wheat. 



There may also be a small quantity of bitumen 

 included in the Ether-extract from Mummy Wheat. 



Nitrogen and Proteid Matter. 



The quantitative changes which the wheat has 

 suffered during storage are comparatively insignifi- 

 cant, and such differences as are found may be said 

 to fall within the limits for normal wheats of 

 different varieties. 



The nature of the changes undergone by the 

 proteid matter, however, is striking in the case of the 

 oldest wheat but quite unworthy of consideration of 

 those grains up to fifty years of age, as has already 

 been shown when the gluten strength of the crushed 

 wheats under examination was discussed. 



The process of decomposition of the wheat gluten 

 is mainly biological, in that bacteria play a very 

 important part both in oxidising the actual nitro- 

 genous matter and in producing acids from the other 

 components of the grain capable of degrading the 

 gluten. 



It is certain that under normal atmospheric and 

 humidity conditions neither bacteria nor fungi could 

 obtain a good hold on the wheat berry, but that, 

 after the passage of a number of years, when the 

 outer protective covering of the grain had itself 

 become oxidised and permeable, the process of 

 decomposition would proceed more rapidly within 

 the grain. 



The period of time necessary to bring about these 

 internal changes is entirely dependent upon the 

 conditions under which the wheat was stored. 



There are other factors which have been shown by 

 various experimenters to have marked effect on the 

 physical characteristics of gluten, and which may be 

 more or less responsible for the reduction in the 

 gluten strength of the flour obtained from the 

 Mummy Wheat. 



The degrading effect of acids has already been 

 mentioned, and the results obtained by Snyder 

 would prove that a flour of higher acidity is less 

 efficient for bread-making, owing to a lack of strength 

 which results from a pronounced decrease in gliadin 

 percentage. 



The differences of opinion between Snyder and 

 Wood and others are mainly as to which is " the 

 cause " and which is " the effect " of acidity ; though, 

 for the purposes required here, it is sufficient to 

 notice that with increase of age there is greater 

 acidity, and, in the extreme case, a complete loss of 

 gluten strength. 



The influence of mineral salts on gluten strength 

 determined by Wood is of great interest to the baker 

 and miller and in cases where the flour is made into 

 dough with water. The general action of salts is 

 that of coagulation or binding and toughening the 

 dough, and often overcomes the degrading influence 

 of an acid when both salt and acid are present. 



Lactic acid of all strengths was found by Wood to 

 reduce the wheat gluten strength, and that propor- 

 tional increases in the quantity of added salt to 

 procure cohesion of the dough were then necessary. 



In the case of a normally air-dried whole wheat, 

 however, the circumstances are different, and, with 

 the exception of the mineral matter held in immedi- 

 ate juxtaposition to the proteid matter, the salt 

 solutions can have little effect seeing that, under 

 fairly constant conditions of temperature and 

 humidity, " flow " does not exist to any extent and 

 that such effect as is produced is purely local. 



In the process of time the action of the self- 

 contained salts may have effect on the gluten, and it 

 is clear from the results obtained by the present 

 writer that sixty years is, under normal conditions, 

 too short a period to allow any appreciable degrada- 

 tion of gluten to take place w ithin the wheat berry. 

 This may be explained by the fact that the salt 

 content of the newer wheats is still high enough to 

 counteract the degrading effects of the acids as they 

 form, and that, as age increases and the salt content 

 of the berry falls, the full influence of the accumu- 

 lating acids gradually becomes more apparent. 



Carbohydrates- — Soluble — and Starch . 



The slight decrease in the Soluble-carbohydrates 

 with increase of age is noticeable though without 

 importance, whilst the starch content of all the wheats 

 examined is constant within the limits of experiment 

 and natural variations when the differences of 

 moisture and proteid matter are taken into account. 



The starch and fibre are undoubtedly the most 

 stable of all the components of wheat, and the 

 granules of starch from even the oldest samples do 

 not show pitting due to enzymic action, a fact which 

 adds further proof to the suggestion that the flow of 

 solution within the berry was restricted, owing to 

 lack of moisture. 



Hush and Fibre. 



The percentage of husk and fibre is practically 

 constant in all the samples of wheat examined. 



