American Journal of Applied Science and Technology
6
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VOLUME
Vol.05 Issue 04 2025
PAGE NO.
6-12
10.37547/ajast/Volume05Issue04-02
Improving the Quality of Gluten-Free Bread Products
Using Bacterial Yeast: The Role of The Fermentation
Process
Djurayeva Nafisa Radjabovna
D.Sc., Associate Professor, Bukhara State Technical University, Bukhara, Republic of Uzbekistan, Uzbekistan
Ganieva Marjona Utkirovna
Master’s Student, Bukhara State Technical University, Bukhara, Republic of Uzbekistan, Uzbekistan
Received:
11 February 2025;
Accepted:
13 March 2025;
Published:
10 April 2025
Abstract:
In recent years, the demand for functional and dietary food products has significantly increased. However,
improving the physicochemical and organoleptic properties of gluten-free products remains one of the key scientific
and technological challenges. One of the main issues in gluten-free bread production is the lack of structural
integrity and desirable organoleptic characteristics. This study examines the role of bacterial yeasts, specifically
lactic acid bacteria (Lactobacillus spp.), in the fermentation process of gluten-free bread products and their impact
on physicochemical, microbiological, and sensory quality parameters. Experimental results indicate that organic
acids, exopolysaccharides, and other metabolites produced during bacterial fermentation enhance the rheological
properties of the dough, optimizing the volume, texture, and organoleptic qualities of the bread. Moreover, due to
the antimicrobial properties of bacterial starter cultures, the shelf life of the bread products was extended, and
their microbiological stability improved. The findings confirm that bacterial fermentation is an innovative and
technologically promising approach for the gluten-free bread industry.
Keywords:
Gluten-free Bread, Bacterial Yeast, Lactic Acid Bacteria, Fermentation, Food Biotechnology,
Exopolysaccharides, Organic Acids, Food Innovations.
Introduction:
In modern food industries, the demand for functional
and health-oriented products has been rapidly
increasing. In particular, the widespread adoption of
gluten-free diets has elevated the need to improve the
nutritional and technological properties of these
products to a strategic challenge [1]. One of the most
significant technological obstacles in gluten-free bread
production is maintaining its viscoelastic properties. In
conventional bread products, gluten plays a central
role in structural cohesion, contributing to the volume
and texture formation of the final product [2]. Bacterial
fermentation, particularly the application of lactic acid
bacteria (Lactobacillus spp.), is being recognized as an
effective solution for improving the organoleptic and
physicochemical properties of gluten-free bread
products [3]. Recent scientific studies have
demonstrated
that
organic
acids
and
exopolysaccharides produced by lactic acid bacteria
optimize the rheological properties of the dough,
enhancing its softness and promoting the formation of
air pockets [4]. Furthermore, the metabolites produced
by these bacteria contribute to extending the shelf life
of the bread while improving its microbiological
stability [2]. Additionally, gluten-free bread products
enriched with probiotic bacteria have gained
considerable consumer demand due to their
scientifically supported beneficial effects on the
digestive system.
The fermentation process enhances the quality and
structure of bread by altering the physical and
biochemical properties of the dough. The utilization of
novel strains of lactic acid bacteria, such as
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American Journal of Applied Science and Technology (ISSN: 2771-2745)
Lactobacillus rhamnosus, L. acidophilus, and L.
fermentum,
has
demonstrated
the
following
advantages:
•
Structural
Integrity
Improvement:
Exopolysaccharides generated during fermentation,
particularly xanthan gum, interact with starch
molecules, reinforcing the structural integrity of
gluten-free bread. This process enhances moisture
retention, improves texture, and results in a softer,
more elastic product with an extended shelf life.
•
Reduction
of
Anti-nutritional
Factors:
Fermentation decreases the concentration of anti-
nutritional compounds, thereby improving the
bioavailability and absorption of essential minerals.
•
Enhancement of Nutritional Value: Bacterial
activity increases the synthesis of B vitamins,
contributing to the overall nutritional profile of gluten-
free products.
The objective of this study is to conduct an in-depth
analysis of the impact of bacterial fermentation on
gluten-free bread products, evaluate its efficacy based
on existing scientific data, and explore its potential
applications on an industrial scale. This research not
only
highlights
the
significance of
bacterial
fermentation in food biotechnology but also promotes
innovative approaches to the production of healthier
food products.
METHODS
Materials
The following ingredients were used for gluten-free
bread production:
•
Primary flours: Brown rice flour (Oryza sativa L.,
"Iskandar" variety, Uzbekistan), sorghum flour
(Sorghum bicolor L., "Uzbekistan-18" variety), corn
starch (Zea mays L., "Sulton" variety), soy flour (Glycine
max L., "Davr" variety).
•
Additives:
Xanthan
gum
(a
natural
polysaccharide produced by Xanthomonas campestris,
widely used as a key stabilizer in the food industry),
sugar syrup, salt, water, and dry yeast (Saccharomyces
cerevisiae).
•
Lactic acid bacterial strains: Lactobacillus
rhamnosus GG, Lactobacillus acidophilus LA-5,
Lactobacillus fermentum ME-3.
Fermentation Conditions
The fermentation process was conducted according to
established
microbiological
and
biochemical
methodologies:
•
Bacterial fermentation was carried out at 30°C
for 24 hours, ensuring optimal growth conditions and
acid production for the lactic acid bacterial strains [5].
•
Dough fermentation was performed at 85%
relative humidity for 30 minutes, which helped
enhance dough structure and improve CO₂ retention
capacity [6].
•
Baking was conducted at 190°C for 45 minutes,
ensuring the preservation of the bread’s internal
structure while balancing the effect of oven
temperature [7].
1. Preparation of Natural Sourdough
The natural sourdough fermentation process involves
the interaction between lactic acid bacteria and yeast,
which improves the physicochemical and organoleptic
properties of the dough while extending its shelf life.
The fermentation process was carried out as follows:
1.
Bacterial Cultivation: Selected lactic acid
bacterial strains (L. rhamnosus GG, L. acidophilus LA-5,
L. fermentum ME-3) were incubated in MRS broth at
30°C for 24 hours, ensuring optimal growth conditions.
2.
Preparation of Fermentation Inoculum: The
bacterial biomass was harvested by centrifugation, and
the obtained cells were suspended in 1 mL of fresh
sterile nutrient medium for subsequent fermentation
steps.
3.
Preparation of Sourdough Base: Each lactic acid
bacterial strain was mixed with equal parts of flour and
water, with the total water content adjusted to 200%
of the flour weight. (For example, 100 g of flour was
mixed with 200 g of water). This high moisture content
created optimal fermentation conditions, enhancing
bacterial growth, enzymatic activity, and dough
elasticity, ultimately improvin
g the bread’s structure
and shelf stability.
4.
Fermentation
Process:
The
prepared
sourdough mixture was incubated at 30°C for 24 hours.
Previous studies indicate that LAB strains such as
Fructilactobacillus sanfranciscensis exhibit optimal
growth at approximately 33°C, while temperatures
exceeding 41°C inhibit their development [8]. Similarly,
Limosilactobacillus pontis strains have been found to
be less competitive at temperatures above 40°C [6].
Thus, an incubation condition of 30°C for 24 hours was
selected to ensure optimal LAB growth and enzymatic
activity.
Optimal incubation conditions enhanced the efficiency
of the LAB fermentation process, significantly
influencing the organoleptic and physicochemical
properties of the dough. The lactic and acetic acids
produced during fermentation lowered the pH,
inhibiting the growth of pathogenic microorganisms
and thereby improving the microbiological stability of
the bread.
Furthermore, exopolysaccharides formed during
fermentation increased the dough’s water re
tention
capacity, enhancing its moisture-holding ability and
improving its textural stability and shelf life.
Additionally, CO₂ and organic compounds generated
during fermentation contributed to increasing the
bread's volume, enhancing its internal structure, and
producing a softer texture.
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American Journal of Applied Science and Technology (ISSN: 2771-2745)
The results demonstrated that sourdough-based
bacterial fermentation yielded a more stable dough
structure with superior organoleptic properties
compared
to
conventional
gluten-free
bread
production methods. This approach confirms that
bacterial fermentation is a promising technological
strategy for producing functional and innovative
gluten-free bread products suitable for large-scale
production.
For each experiment (Trials 1, 2, and 3), specific
ingredient quantities are provided in separate tables.
Table 1. Standard Protocol.
Ingredient
Quantity
Description
Brown rice flour
100 g
Main flour
Sorghum flour
50 g
Supplementary flour
Soy flour
20 g
Supplementary flour
Corn starch
30 g
For structural integrity
Xanthan gum
2 g
Stabilizer
Sugar syrup
15 g
Enhances taste and fermentation
Salt
1.5 g
Enhances taste
Dry yeast (*Saccharomyces cerevisiae*)
3 g
For rapid leavening
Water
400 mL
200% of flour weight (optimal moisture)
Lactic acid bacteria (starter inoculum)
5 mL
Lactic acid bacteria (approximately 2% v/w ratio)
•
Fermentation: Incubation at 30°C for 24 hours, followed by 30 minutes of resting at 85% relative humidity.
•
Baking: Conducted at 190°C for 45 minutes.
Table 2. High Starter Inoculum and Short Fermentation.
Ingredient
Quantity
Description
Brown rice flour
80 g
Reduced compared to the standard recipe (for a lighter texture)
Sorghum flour
50 g
Supplementary flour
Soy flour
20 g
Supplementary flour
Corn starch
40 g
Enhanced structural integrity (increased proportion)
Xanthan gum
2.5 g
Slightly increased for improved stabilization
Sugar syrup
15 g
Enhances taste and fermentation
Salt
1.5 g
Enhances taste
Dry yeast (*Saccharomyces cerevisiae*)
3 g
For rapid leavening
Water
380 mL
Slightly reduced to match flour composition (for moisture control)
Lactic acid bacteria (starter inoculum)
5 mL
Standard amount (adjusted due to extended fermentation time)
•
Fermentation: Incubation at 30°C for 18 hours, followed by a short resting phase (20 minutes) to monitor CO
₂
retention.
•
Baking: Conducted at 190°C for 45 minutes.
•
In this version, the higher inoculum level leads to a faster pH reduction, allowing for the observation of rapid enzymatic
changes in the dough.
Table 3. High Inoculum Amount for Accelerated Acid Production.
Ingredient
Quantity
Description
Brown rice flour
100 g
Main flour
Sorghum flour
50 g
Supplementary flour
Soy flour
20 g
Supplementary flour
Corn starch
30 g
For structural integrity
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American Journal of Applied Science and Technology (ISSN: 2771-2745)
Xanthan gum
2 g
Stabilizer
Sugar syrup
15 g
Enhances taste and fermentation
Salt
1.5 g
Enhances taste
Dry yeast (*Saccharomyces cerevisiae*)
3 g
For rapid leavening
Water
400 mL
200% of flour weight (optimal moisture)
Lactic acid bacteria (starter inoculum)
7 mL
Increased inoculum amount to enhance rapid acid production
•
Fermentation: Incubation at 30°C for 30 hours (extended time facilitates EPS and other metabolite production), followed
by an additional 30-minute rest at 85% relative humidity.
•
Baking: Conducted at 190°C for 45 minutes.
Initial Preparation
1. Ingredient Measurement
Dry Ingredients: Brown rice flour, sorghum flour, soy
flour, corn starch, xanthan gum, sugar syrup, salt, and
dry yeast are each precisely measured using an
analytical balance with a sensitivity of 0.01 g. Water
and Starter Inoculum:Water is measured using a
graduated measuring cylinder. Lactic acid bacteria
inoculum is measured using a volumetric pipette for
accuracy.
2. Dough Preparation
Mixing Dry Ingredients: All pre-measured dry
ingredients are combined in a spiral mixer bowl.Mixing
duration: 2 minutes at low speed (20
–
30 rpm) to
ensure uniform distribution and homogeneity.
Incorporating Water and Starter Culture: The pre-
measured water and lactic acid bacteria inoculum are
added to the dry ingredient mixture. Mixing process:
Conducted using a spiral mixer at medium speed (40
–
50 rpm) for 8 minutes to achieve optimal dough
consistency. Outcome: A smooth, elastic, and well-
homogenized dough with a consistent texture.
3. Primary Fermentation
Dough Preparation for Fermentation: The prepared
dough is placed in a sealed fermentation container
(plastic or glass) to maintain optimal conditions.
Fermentation Conditions and Duration: Fermenter
Specifications:
A laboratory fermenter capable of maintaining a
temperature of 30°C and relative humidity of 85% (e.g.,
Binder KBF model). Fermentation Timeframes:
Experiment 1: 24 hours, experiment 2: 18 hours,
experiment 3: 30 hours.
Sampling and Analytical Measurements: Dough
samples are collected every 6 hours for analysis, with
the following parameters measured: pH level using a
digital pH meter. Total titratable acidity (TTA) using a
titration method, expressed in mg KOH/g.
Figure 1. Standard Protocol.
pH Values:
•
0 hours: 6.5
•
6 hours: 5.8
•
12 hours: 4.9
•
18 hours: 4.1
•
24 hours: 3.8
Total Titratable Acidity (TTA, mg KOH/g):
•
0 hours: 2.5
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•
6 hours: 4.5
•
12 hours: 7.5
•
18 hours: 10.0
•
24 hours: 12.3
According to the standard protocol, pH gradually
decreased while TTA steadily increased during
fermentation. These changes reflect the active
metabolic processes of lactic acid bacteria.
Figure 2. High Starter Inoculum and Short Fermentation.
pH Values: 0 hours: 6.5, 6 hours: 5.5, 12 hours: 4.4, 18
hours: 3.8.
Total Titratable Acidity (TTA, mg KOH/g): 0 hours: 2.5,
6 hours: 5.5, 12 hours: 9.0, 18 hours: 12.3
Due to the increased inoculum concentration, the
fermentation process initiates more rapidly. As a result,
pH decreases significantly within 18 hours, while TTA
increases at a faster rate. This version demonstrates a
higher fermentation rate, achieving optimal acid
production within a shorter time frame.
Figure 3. High Inoculum Amount for Accelerated Acid Production.
pH Values: 0 hours: 6.5, 6 hours: 5.9, 12 hours: 5.0, 18
hours: 4.2, 24 hours: 3.8, 30 hours: 3.5
Total Titratable Acidity (TTA, mg KOH/g): 0 hours: 2.5,
6 hours: 4.8, 12 hours: 7.0, 18 hours: 9.0, 24 hours:
11.0, 30 hours: 13.0
Due to modifications in flour composition and an
extended fermentation period (30 hours), a higher
production of metabolites (exopolysaccharides and
organic acids) is expected. As a result, the pH decreases
further in the final stages, while TTA reaches a slightly
higher level. This process enhances the structural
integrity and shelf stability of the dough.
4. Additional Resting Phase: after fermentation, the
dough is placed in a humidity chamber with 85%
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American Journal of Applied Science and Technology (ISSN: 2771-2745)
relative humidity for 30 minutes. This step enhances
the final dough rise and C
O₂ retention capacity.
5. Baking Process
- Preheating the Oven: before placing the dough in the
oven, it is essential to preheat it to the optimal
temperature, typically around 450°F (ca. 232 °C). This
ensures that the initial heat shock helps in achieving a
good oven spring, allowing the dough to rise rapidly
and develop a desirable crust.
1. Discuss the role of humidity in dough fermentation
and how it affects flavor development. 2. Explain the
importance of maintaining a consistent baking
temperature and its impact on crust formation. 3.
Explore different methods of enhancing CO₂ retention
in various types of dough. 4. Detail the steps involved
in preparing the humidity chamber and its effect on
dough consistency. 5. Provide tips on adjusting oven
techniques for different recipes to achieve desired
results.
- The laboratory oven is preheated to 190°C.
- The internal temperature is monitored using a
thermocouple.
- Baking Conditions:
- Dough molds are placed into the oven and baked for
45 minutes.
- After baking, the loaves are carefully removed from
the molds and cooled on a wire rack for 1 hour to
stabilize the internal structure.
6. Final Analysis
1. Rheological Properties
A texture analyzer was used to measure the following
parameters:
Hardness (N/m): Assesses the structural integrity and
firmness of the bread.
Springiness (%): Reflects the lightness and recovery
ability of the bread after compression.
Testing Conditions:
Sample size: Cubes cut into 2×2×2 cm dimensions.
Compression probe: P/36R cylindrical compression
probe was used.
Compression speed: 1 mm/s.
Maximum compression depth: 5 mm.
Table 4. Springiness measurement: The height recovery percentage (%) was recorded after compression.
Experiment
Hardness (N/m)
Springiness (%)
1
5.2
85
2
4.8
82
3
5.5
88
Table 5. Organoleptic Evaluation
Experiment
Taste (10-point scale)
Aroma (10-point scale)
Appearance (10-point scale)
1
8.2
7.9
8.0
2
7.8
7.5
7.7
3
8.5
8.3
8.4
Equipment:
•
pH meter (Mettler Toledo SevenCompact
pH/Ion S220)
–
Used for precise pH measurement.
•
Titrator (Metrohm 848 Titrino Plus)
–
Used to
determine total titratable acidity (TTA).
•
Microbiological incubator (Memmert IN110)
–
Used for evaluating bread shelf life and conducting
microbiological analysis.
pH and TTA Measurements:
•
A 10 g bread dough sample was dissolved in
100 mL of sterile distilled water.
•
The pH value was measured using a pH meter.
•
Titration with 0.1 M NaOH was performed
using a titrator to determine total titratable acidity
(TTA).
Microbiological Stability Assessment:
•
Baked bread samples were stored in a
microbiological incubator at 30°C for 10 days.
•
Every 24 hours, the samples were examined for
visual changes and microbial growth assessment.
RESULTS
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American Journal of Applied Science and Technology (ISSN: 2771-2745)
Table 6. Microbiological Stability
Experiment
pH
TTA (mg KOH/g)
Shelf Life (days)
1
3.8
12.3
5
2
3.8
12.3
4
3
3.5
13.0
6
CONCLUSION
This study thoroughly investigated the potential of
bacterial fermentation to improve the quality of gluten-
free bread products. The findings indicate that the use
of lactic acid bacteria significantly enhances the
rheological,
organoleptic,
and
microbiological
properties of the bread. The key findings of this study
are
as
follows:
The
organic
acids
and
exopolysaccharides produced during the fermentation
process optimized the rheological properties of the
dough, improving the structural integrity of the bread.
According to Experiment 3 (extended fermentation),
increased metabolite production resulted in the best
elasticity
and
moisture
retention
capacity.
Microbiological analysis demonstrated that the shelf
life of gluten-free bread can be extended through
fermentation. A lower pH and higher TTA contributed
to increased antimicrobial activity, thereby enhancing
the microbiological stability of the product.
Organoleptic evaluation revealed that the taste,
aroma, and texture of the fermented bread were
positively rated by consumers. This study provides
scientific evidence that bacterial fermentation
technology can significantly improve the quality of
gluten-free bread. Fermentation using lactic acid
bacteria enhances the softness, elasticity, sensory
attributes, and shelf life of the product.
Future scientific and industrial research can further
expand the application of this technology, facilitating
the production of high-quality gluten-free bread
products that align with healthy dietary principles and
meet consumer demands.
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