The Sun.
London, England, 1857-04-02 00:00:00

ROYAL POLYTEORNIC INSTITUTION.

Yesterday a number of scientific gentlemen, physicians,
&c., were invited to the Polytechnic Institution, to witness
the results of the improved system of fermenting and making
pure bread, as practised by Mr. C. Stevens, at his bakery
in the Cambridge road, near the Eastern Counties Railway
station. Mr. Pepper undertook to explain the chemistry
of bread-making, and to show the different stages of the
process as conducted by Mr. Stevens, and by the London
bakers. He pointed out, in the first place, the chemical con-
stituents of flour and of bread. Good unadulterated bread
contains the large proportion of 78 parts of water in every
100, so that even when bread is pure it does not contain
more than 22 parts of nutritive matter, and the adulterated
article frequently contains very much less. There are
different modes of adulteration commonly practised,
some of which have for their object to improve
the appearance of the bread when it is made with
coarse or with mixed flour; and other modes of adultera-
tion increase the quantity, by causing a larger ab-
sorption of water. Mr. Pepper alluded to the plan of
biead•making which was introduced into this country, a
few years ago, by some French chemists, who professed to
be able to make a much larger quantity of bread for a given
weight of flour than had been before done. Their plan was
put in operation at Marylebone Workhouse, where, from a
sack of flour, they made double its weight of bread. The
process was conducted secretly ; but Mr. Pepper, who was
rweaatslypriondeurecaesdedbypotwheeradof-
requested by the v-orkhoue authorities to analyse the
discoveredoul thataucingccedehe,
da
andtec haci euiainerf effect
making
catgll quantity of alum. By
bread,tdaphei
by using the same agents, Mr. Pep-
even a larger propor-
tion of bread from a given weight of flour than the French
chemists. Bread of that kind is not unwholesome, but as
itrs
sioso
absorbing
said
onefligu eh
hot
ahialtdeee drds,
it contains a smaller proportion of nutriment, it is unfair
to sell it as wheaten bread. The proportion of rice which
Mr. Pepper employed was lilb. to 41b. of flour. Mr.
Stevens, for the purpose of showing the effect of rice
when, thus introduced, had brought to the institution
a large pile of loaves, which he had made from 141 b. of
flour, with the addition of rice. It presented the ap-
pearance of very good bread, and was well tasted, and it
possessed the property also of not becoming so dry as
ordinary bread. Mr. Pepper then noticed the more
objectionable adulterations to which some bakers have re-
course, even to the introduction of sulphate of copper, a
few grains of which in a sack of flour produces great effect
in the working of the dough, and in the appearance of the
bread. The common process of bread making,
as adopted
by bakers in general, was then noticed, and samples of the
yeast and of the dough in its various stages were placed on
the lecture table for illustration, togethr with a number
of loaves that had been purchased from cheap bakers, to
contrast with the pure bread made by Mr. Stevens. The
process adopted by the latter was then described, and illus-
trated in the same manner by a variety of samples. The
chief difference between Mr. Stevens' system of fermenting
the dough and that of other bakers consists in a previous
mixture of the yeast into a thin batter with flour and
water. The yeast he uses is obtained from pale ale brew-
eries, and the mixture of it with the flour is allowed to fer-
ment for 24 hours. He then uses it as bakers usually em-
; ploy the unmixed yeast, and he finds that the fermentation
with the diluted yeast is more diffused and effective, and
there is less risk of the bread tasting bitter. The speci-
mens of dough undergoing fermentation certainly showed_
great activity in the process. The purity of Mr. Stevens'
bread depends much on the care he takes to obtain unadul-
terated flour, and the results were proved roost satisfac.
by specimen loaves of the bread, which were distri-
buted The taste of the bread was
torily
among
the
upulpan_y.
enough to prove its purity, and was, for practical purposes,
better evidence of its excellence, than the microscopical
tests to which it was subjected by Dr. Hassall. Diagrams
of the appearance of flour and its adulterations, as magni-
Ified by a powerful microscope, as taken by Dr. Hassall,
were exhibited, and there were also shown numerous spe-
cimens of meal and flour in different stages of progress. The
lecture formed altogether a very interesting exposition of
the subject of bread-making and its adulterations.