Analysis of information sources in references of the Wikipedia article "Digestive biscuit" in English language version.
Digestive biscuits are prepared in such a manner that they may contain diastase, the nitrogenous transforming matter of malt; but whatever quantity of this substance they may contain in the condition of dough is destroyed in the process of baking.
A new competitor in this field was Paterson's Extract of Malt, exhibited by the Phoenix Chemical Works, Glasgow; the odour and flavour of this was excellent, and it is said to be rich in diastasic power. Prepared from it was exhibited a series of digestive biscuits, rusks and bread by John Montgomerie, of Glasgow. In making these part of the starch of the flour is changed by being mixed with the malt extract and water and kept for some time at a suitable temperature; the yeast being probably added to another portion of flour and water, to form dough to mix with the above before baking. These biscuits seemed to be appreciated by visitors. Messrs. Hill and Son also exhibited some malted nursery biscuits. Benger's well known digestive ferments were well displayed, together with an essence of rennet recently introduced.
Professor Johnston remarks that -- "The grain of wheat consists of two parts, with which the miller is familiar -- the inner grain and the skin that covers it. The inner grain gives the pure wheat flour; the skin when separated, forms the bran."
The Parisian white bread is prepared with the finest flour (1re marque), which does not contain any bran. If 100 parts wheat yield 70 parts of this flour, the remainder will consist of 10 parts bran and 20 parts coarse brown meal, this latter consisting of 3 parts fine bran and 17 parts white flour.
By allowing the germ and all but the outer, coarser layers of broad bran to mix in with the flour, we get the sweet-tasting brown meal producing the brown bread so much in favour amongst sections of the community.
Digestive biscuits, semi-sweet and made with brown meal, can no longer be made under that name in the United States, but the English version is widely available.
Huntley and Palmers, a rival bakery, launched its own digestive biscuit in 1876
YouGov Ratings data shows McVities, Cadbury's and Walkers products dominate the list of Britain's favourite biscuits