الفهرس 
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Abstract
Part I: Chemical analysis and prop~~~ie~ __~f flours, yeas~
and starter used in breadmaking of Egyptian breads.
The present part include data on chemical composition
of wheat flours used commercially in production of some
types of Egyptian bread as well as the reological properties of
their doughs. Furthermore, yeasts and starter used in making
various Egyptian breads were also analysed from the point of
their chemical characteristics fermentation power and viable
yeast cell count.
1- Chemical analysis of wheat flours indicated that
72~ extraction flour, which is mostly used for producing
Nhite pan bread in Egypt, had lower content in crude protein
~ther extract and ash than the 82% extraction flour which
is mostly used for breadmaking of Baladi types. Although
both types of flour did not differ with respect to their
content in reducing sugar, (averaged 0.9%) they varied
greatly in their content of non-reducing sugars. Titratable
acidity for the 82% extraction flour was slightly
lower (0.19%) than that for the corresponding flour
(0.24%).
2- Chemical analysis of yeasts revealed that active
dry yeast {ADY} contained a higher content of protein, ash
oil and reducing sugars than (BY). Furthermore, it possesed
higher titratable acidity, and lower PH than .fresh BY.
However, ADY had only one third of the amount of non-reducing
sugars present in BY. Moisture content of both types
of yeast did not exceed the values specified by the Egyptian
standard for yeast.
3- Sol tani starter (fermented mother douch) , T.1’l.ic’l.
is used in producing mawi type of Baladi Dread, showed high
crude protein and ash contents, but a very low reducing
sugars. Acidity was considerably very high in soltani starter
compared to those of yeasts.
4- Examination of rheological properties of the two
flours used for making Egyptian bread by Brabender Farinoghaph
indicated that flour of 72% extraction is a typical
weak flour. Farinograph water absortion value was lower
for the 82% extraction flour than that the oth~r type.
The Extensogram properties indicated” that both flours differ
greatly with respect to their stretching properties of
their doughS. The 72% extraction flour had much better extansibility
properties than the 82% extraction~ne.
5- Brahender rest-period curves of doughs made
using no yeast and equal concentration of BY and ADY obtained
for periods of five hrs. revealed that comparable
changes in dough consistency were attained.
6- Preliminary measurement of fermentation power of
BY and ADY (10 Trails for each type) revealed comparable
results which were higher than those required by the Egyptian
standard for yeast.
7- Determination of total viable yeast cells, as
determined by plat count technique, showed that ADY ha~
much higher count than BY. However, values for viab18 yeast
cell count of both BY and ADY were higher than those required
by the Egyptian standard for yeast{
Part II. Effect of, fermentation condition on breadmaking
of white pan bread.
The present section in concerned with optimization
of conditions of fermentation during the productirn of
white pan bread as comrrlerciallyproduced of Egypt. Moreover,
effect of using BY and ADY in panary fermentation were
compared from the point of gas produc~ion rate, chemica~
changes in doughs as well as chemical, baking and organoleptic
properties of loaves.
8- Farinograph fermentation curves at different rest
period times (5-6 hr.) of doughs formula containing increased
levels of BY or ADY (0.5, 1, 1.5, 3 and 6%) de~oDstrated
that certain changes with increasing amount of yeast
with type of yeast in dough formula and with duration of
fermentation period. Slackening of ADY doughs was apparent
when yeast concentration was higher than 1.5% and also
after 3 hr. of fermentation. However, the final sections of
curves (5 or 6 hxs .) demonstrate that BY doughs ha cl more
strength left than ADY dough.
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9- Farinograph fermentation curves proved to/useful
in studying the vascoelastic properties of fermentation
doughs under different conditions.
10- Analysis of doughs in function of increased conc-
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entration of BY and ADY indicated that/content of fresh
mixed dough was slightly reduced after the :fermentation
period was elapsed with all the tested levels of BY and
ADY. Moreover, no siginificant differences in moisture
content were observed between BY and ADY doughs before
and after fermentation at all yeast concentrations.
11- Titratable acidity of BY and ADY doughs was
increased by fermentation and the increase was greater
with increasing yeast concentration in the dough. However,
acidity of fermented ADY doughs increased to a higher extent
than the corresponding fermented BY dou~hs and such increase
was more pronounced by increasing” yeast concentration
12- Bread showed lower moisture content than their
respective doughs, due to the effect of baking temperature.
However, bread prepared from BY and ADY doughs showed comparable
moisture content except at higher yeast concentrations
(2.6, 3 and 6%) .
13- Bread had higher acidity than their fermented
doughs and the increase was proportional to the increase in
yeast concentration. Moreover, bread baked from ADY doughs
had higher acidity than the corresponding loaves and such
increase was more upon increasing yeast concentration in the
dough.
14- Values for PH had the same trend occurred for
acidi ty values of doughs and bread, but 1~ the opposi te
direction; as PH increased acidity decreased.
15- Reducing sugars were higher in the AnY unfermented
doughs than the unfermented BY doughs. Fermented doughs
showed lower content reducing sugars than unfermented doughs
of both types. However, such a decreased oecame ~ore pronounced
with increasing yeast concentration in dough.
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16- Non- reducing/decreased upon fermentation and
the decrease was greater by increasing yeast concentration
until they diminished completely at the higher yeast concentration
(3 and 6% in ADY doughs and. only 6% with BY in
dough) .
17- Bread contained higher reducing sugars than their
doughs only at the lower yeast concentration in the 00uSh
but such hiqh content was reduced gradually by increasing
yeast concentration. Bread baked from BY doughs had higher
reducing sugars than the correspondingADY bread at all i
levels of yeast tested.
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18- Bread loaves contained/non- reducing sugars than
their respective doughs and such decrease was greater when
yeast concentration w as incrEc..ssd. Bread prepared from BY
doug~s snowed a higher content in non reducing s~gars than
the corresponding ADY bread. In general” total sugars content
was higher in BY bread than ADY bread.
19- Effects of increased concentration of ADY and BY
yeast on baking characteristics of pan bread loaves appeared
that loaf weight and volume increased gradually with increasing
the concentration of BY. However, the inclusion of
more than 2.6 % yeast did not cause any further increase in
bread weight. Maximum loaf volume and specific volume were
obtained using 3% BY in dough. Bread characteristics of
ADY doughs were improved with increasing yeast concentration
up to only 1.5% and then clearly decreased.
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20- Organoleptic evaluation/loaves revealed that ike
higher scores were obtained for bread made for 3% BY and
1.5% ADY. Maximum scores (94.4) were givento the 1.5%
ADY bread which indicate its higher acceptability over
those made from BY doughs.
21- Results of the present part of study demonstrated
that ADY could be used in amount of half that of cornpressed
baker’s yeast and produce white pan bread of superior
quality, better acceptability and with less fermentation
losses. Therefore,its conversion ratio to BY would
be 50% in the fresh weight and only 32 - 33% on the same
dry matter content.
B- Effect of type of yeast in function to duration
of fermentation time.
22- Estimation of gas production rate in douqh for
a baking formula for white pan bread containtng 3% BY ano
1.5% AnY demonstrated that the highest amount of gas was
produced during the first hour of fermentation in both
doughs. However, after 1.5 hr., ADY dough showed slightly
higher gas production rate than the corresponding BY dough
and continued afterwards in such trend. Using AnY at 1.5%
of dough ingredient produced similar dough rising activity
to that containing 3% BY, which indicate comparable yeast
strengtn in both doughs.
23- The effects of subjecting doughs of white pan
bread to different fermentation periods (1, 1.5, 2, 2,5
and 3 hr.) on the chemical properties of these doughs and
their baked loaves prepared using 3% BY and 1.5 ADY of
the formula ingredient were studied.
24- Moisture content of freshly mixed yeasted doughs
of zero fermentation time was lower in ADY dough than BY
dough. Both doughs showed gradual decrease in moisture
content by increasing the fermentation time, and reached
the maximum decrease after 3 hr. of fermentation. All ADY
doughs exhibited lower moiture content tha~ thp corresponding
BY doughs with all the fermentation periods tested.
25- Titratable acidity of BY and ADY doughs and loaves
increased gradually by increasing the time of fermentation:
where the highest values were attained after 3 hours. No
great difference in acidity values was observed between the
two doughs and their baked loaves. The acidity of loaves was
found to be higher than that of their original doughs.
26- Reducing sugars content showed gradual decrease
in BY and ADY doughs by increasing the fermentation time~
except after the first hour of fermentation. The increase
in reducing sugar during the first hr. of fermentation was
more higher in BY dough than in AnY dough.