dc.description.abstract | Whole wheat bread is increasingly consumed in Rwanda. Bread wheat is among the top priority
crops that Rwanda has promoted to boost the national economy. However, bread made from
locally produced wheat varieties has been claimed to be of low acceptance. The objective of this
study was to evaluate the effect of fermentation, spent coffee grounds and juices of lemon fruits
and roemary leaves on quality of whole wheat bread. Whole Wheat flour (W) from wheat varieties
(Gihundo, Kibatsi, Nyaruka and Reberaho) grown in Musanze, Kinigi, Rwanda, spent coffee
grounds (SCG), juice from lemon fruit (L), juice from rosemary leaves (R) and fermentation
duration were assessed for their effect on the physical and sensory characteristics, proximate
composition, acrylamide content and microbial contamination of bread during 7 days of storage at
room temperature (17-23oC). The mixture of whole wheat flour from the four wheat varieties,
spent coffee grounds, juice from lemon fruit, juice from rosemary leaves, salt and water were
fermented. Instant dry yeast was used as a raising agent at 34oC, 60% relative humidity for 60 min
and 39oC, 85% relative humidity for 120 min. The dough was baked at 180oC for 20 min.
Whole wheat flour from Gihundo variety had the highest values of ash content (1.47 %), total
dietary fiber (15.97 %), water absorption capacity (89.00 %), dough development time (7.62 min)
and brightness (84.67 %). Whole wheat flour from Nyaruka variety showed the lowest values of
water absorption capacity (80.00 %), dough development time (6.33 min) and brightness (80.33).
While whole wheat flour from Reberaho variety exhibited the lowest values of ash content (0.98
%) and total dietary fiber (12.44 %). There was no significant difference (p > 0.05) in protein
content (10.00 % and 10.85 %) among whole wheat flours from the four wheat varieties. Whole
flour from Gihundo wheat variety exhibited high values for most of the physicochemical
characteristics determined in comparison to the other three varieties. Thus, the wheat flours from
all the varieties could possibly be categorized as all-purpose since their protein contents were
between 9% and 12%. It is important to select grains or flour from the wheat varieties based on
the individual cultivar because their derivative products could have a more desired quality.
The control breads (W breads) were made from whole wheat flour dough fermented for 60 min
without incorporation of SCG and LR. The control bread samples were firmer than the breads
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containing SCG and SCG+LR with the same time of fermentation. The long fermentation (120
min) and the inclusion of spent coffee grounds, and spent coffee grounds + juices of lemon fruits
and rosemary leaves in doughs, caused the supplemented breads to have lower L*, a* and b* values
than control breads. Low L*, a* and b* values indicate minimum darkness, redness and yellowness
of bread. Aroma, taste and appearance of spent coffee grounds+juices of lemon fruit and rosemary
leaves breads from doughs fermented for 120 min were the most liked. All whole wheat breads
supplemented with spent coffee grounds, and spent coffee grounds + juices of lemon fruits and
rosemary leaves, satisfied consumers’ preferences. Whole wheat breads supplemented with spent
coffee grounds, and spent coffee grounds+juices of lemon fruit and rosemary leaves were low in
protein, fat and ash contents and higher in dietary fiber than control breads. Control breads from
Gihundo variety had the highest acrylamide content (47.00 μg/kg). Addition of spent coffee
grounds + juices of lemon fruit and rosemary leaves in dough fermented for 60 min reduced
significantly (p≤0.05) the acrylamide formation in control breads from 47.00 μgkg-1 to 10.50 μg
kg-1.
Total viable counts (TVC) and total molds and yeasts (TMY) significantly (p≤0.05) increased with
the storage time of 7 days. Whole wheat bread with added spent coffee grounds + juices of lemon
fruit and rosemary leaves (dough fermented for 60 min) from Nyaruka variety and whole wheat
bread containing spent coffee grounds (dough fermented for 120 min) from Gihundo variety had
the lowest and the highest TVC, respectively, on 7th day of storage. While whole wheat bread
supplemenred with spent coffee grounds + juices of lemon fruit and rosemary leaves (dough
fermented for 60 min) from Kibatsi variety and whole wheat bread containing spent coffee grounds
(dough fermented for 120 min fermentation) from Reberaho wheat variety showed the lowest and
highest TMY, respectively, on 7th day of storage. All whole wheat breads from dough fermented
for 120 min had lower TVC than those from dough fermented for 60 min, whereas it was the
opposite for TMY. TVC for all breads up to 5th and on 7th day of storage was within the satisfactory
and borderline ranges which are <4 log cfu g-1, and between 4 log cfu g-1 and 6 log cfu g-1,
respectively. On the 7th day, whole wheat bread supplimented with spent coffee grounds + juices
of lemon fruit and rosemary leaves followed by whole wheat bread containing spent coffee
grounds, showed lower TVC than control breads. The application of spent coffee grounds and
juices of lemon fruit and rosemary leaves as generally recognized as safe natural ingredients can
be exploited by bakeries to improve the sensory attributes and shelf stability of whole wheat bread. | en_US |