Res. J. Appl. Sci. Vol., 2(3): 88-100, 2015
Journal of Research in Applied sciences. Vol., 2(3): 88-100, 2015
Available online at http://www.jrasjournal.com
ISSN 2148-6662 © Copyright 2015
ORIGINAL ARTICLE
Technological Properties of Lactic Acid Bacteria
(LAB) Isolated From Various Sudanese Fermented
Foods
Hinda A. B. Abd Elmaged, Yasmeen Y. A. Elyas, Nuha M. E. Yousif, and Isam A.
Mohamed Ahmed*
Department of Food Science and Technology, Faculty of Agriculture, University of Khartoum,
Shambat 13314, Sudan
*Corresponding Author Email: isamnawa@yahoo.com
Abstract: In this study, twenty-five strains of lactic acid bacteria (LAB) were isolated from
various Sudanese fermented foods (Sorghum dough, Fermented Milk, Cheese, Pickles, and
Sausage). Phenotypic and biochemical tests revealed that the Enterococci (44 %), Lactobacilli
(40 %) and Pediococci (16 %) were obligatory homofermentative according to their growth
characteristics and production of gas (CO2) from glucose fermentation. Following the
identification, evaluation of the technological properties namely; acidification activity,
production of alpha-amylase, haeme-dependant catalase, and degradation of anti-nutritive
tannins of LAB strains was carried out. Technological properties were investigated with a view
towards selection of appropriate starter cultures. Pediococci had the highest rate of acidification
with a ∆pH of more than 2 after 12 h incubation. However, Enterococci and Lactobacilli had
high rates of acidifying initially (6 h), but ∆pH was below 2 after 12 h incubation. With the
exception of strains SH1, SH2 and SA6 having ∆pH 2.27, 2.27 and 2.2 respectively. None of the
LAB was found to produce α-amylase when grown on MRS containing starch. All isolates of
Enterococci, Lactobacilli, and Pediococci produced haeme-dependant catalase. Fermentation by
Enteroccoci, Lactobacilli, and Pediococci as starter culture in sorghum dough batches have the
ability to reduce the tannin content, however Lactobacilli strain showed the highest ability to
degrade tannin (1.7% to 0.9%) in 6 h fermentation. The Enteroccoci and Pediococci strains
required 24 h fermentation to reach 1% tannin content.
Keywords: Lactic acid bacteria, Sorghum, Sudanese fermented foods, Tannin degradation.
Introduction
Fermentation is one of the oldest
biotechnology
approaches
of
food
processing and preservation that extensively
88
applied in both developed and developing
countries. Over thousands of years, the
demands of producing and consuming
fermented foods has extremely increased,
and consequently these foods occupied a
Res. J. Appl. Sci. Vol., 2(3): 88-100, 2015
substantial part of the diet worldwide (Elyas
et al., 2015). The explosion in the
production and consumption of fermented
foods is due to the increased demand for
nutritious, safe, natural, additives-free, and
well-preserved foods (Vaughan et al., 1994).
Fermentation enhances the nutritional
quality of foods through the biosynthesis of
vitamins, essential amino acids and proteins,
improving protein and fiber digestibility,
enhancing micronutrient bioavailability, and
degrading anti-nutritional factors (Giraffa,
2004). It also contributes to food safety and
sustainability particularly under conditions
where refrigeration or other foods
processing facilities are not available such as
in arid and semi-arid rural areas in Sudan
(Elyas et al., 2015). Food fermentation
covers a broad range of microbial and
enzymatic processing of food and
ingredients
to
achieve
desirable
characteristics such as prolonged shelf-life,
improved
safety,
attractive
flavour,
nutritional enrichment, and health promotion
(Giraffa,
2004;
Holzapfel,
2002).
Throughout the fermentation processes,
microorganisms played a key role in the
production of specific metabolites such as
acids, alcohols, enzymes, antibiotics,
carbohydrates, which contribute to the safety
and nutritional quality of fermented foods.
Of them, lactic acid bacteria (LAB) that is
generally regarded as safe (GRAS), play an
essential role in the majority of food
fermentations and preservation, and a
extensive variety of strains are routinely
employed as starter cultures in the
manufacture of dairy, meat, vegetable, and
bakery products (Elyas et al., 2015; Giraffa,
2004; Saeed et al., 2014). This due to the
fact that LAB has several vital technological
properties such as acid production in
different
media
and
at
different
temperatures, proteinase and peptidase
activities, autolysis, production of volatile
compounds, resistance to bacteriophages,
88
and production of inhibitory compounds
(Piraino et al., 2008). These properties are
important for the use of LAB as starters or
adjuncts to maintain and improve the
nutritional, sensory, and safety qualities of
final products (Piraino et al., 2008), and
their evaluation in the screening of proper
starter culture from natural environments
has been and still on the rise in recent years.
Due to the frequent droughts and famines
in many African countries, recent decades
have witnessed increased interest in
recognizing African indigenous fermented
foods, with the aim to provide better
prospects for long-term food sustainability
in those countries. Like other African
countries, fermented foods of the Sudan are
numerous and varied, and many indigenous
fermented foods of animal or plant origin
are still widely consumed and highly
appreciated (Dirar, 1994; Elyas et al., 2015;
Saeed et al., 2014). In Sudan, fermented
foods are prepared from numerous raw
materials such as sorghum, pearl millet,
dates, honey, milk, fish, meat, wild plants,
marginal food crops and even skins, hooves,
bones, caterpillars, locusts, frogs and cow
urine (Dirar, 1994). The preparation and
storage of Sudanese fermented foods are
strongly dictated by the ecology of a hostile
environment of drought, desertification and
recurrent food shortage (Dirar, 1994), there
are thus considered as famine or survival
foods. However, these fermented foods are
still mainly prepared at the household level
under poor sanitary conditions and marketed
through informal routes (Elyas et al., 2015;
Saeed et al., 2014). Accordingly, many
different contaminating microorganism
and/or indigenous microflora involved in
this fermentation processes could be
expected. In addition, there is a lack of data
on the technological properties of
microorganisms
involved
and
their
metabolic impact on flavour, hygienic safety
and shelf life of these products. Therefore,
Res. J. Appl. Sci. Vol., 2(3): 88-100, 2015
the aim of this study was to characterize the
technological properties of LAB isolated
from Sudanese fermented foods to develop
starter cultures with real technological
characteristics for the preparation of
products with consistent taste and nutritional
quality, as well as improved marketability.
Materials and Methods
soluble starch. The plates were incubated at
37ºC overnight, after which they were
flooded with iodine. A colorless area around
the growth indicated a positive test. Bacillus
subtilis strain DSM 2109 and Escherichia
coli ATCC 29522 (obtained from the
Department of Veterinary Microbiology,
Faculty of Veterinary Sciences, University
of Khartoum, Sudan) were used as positive
and negative controls, respectively.
Food samples and LAB isolates
Production of Haeme-dependant Catalase
In this study, twenty-five LAB strains
those isolated previously from six types of
Sudanese fermented foods; sorghum dough,
mish, yoghurt, cucumber pickles, cheese and
meat sausage (Saeed et al., 2014) were used
for assessing the technological properties
such as acidifying activity, production of αamylase, haeme-dependant catalase, and
tannin-degrading abilities. All chemicals and
reagents used were of technically
recommended analytical grade.
Acidification activity of LAB
In this assay, MRS broth (De Man et al.,
1960) was inoculated with 1% of a 24 h
LAB culture and incubated at 37 ºC for 36 h.
At intervals of 6, 12, 24, and 36 h, the
culture was centrifuged at 3000 × g for 15
min at 4°C and the supernatant recovered
was used for pH measurement using a pH
meter (Model L15-1260/7, Pusl, Munchen,
Germany). ∆ pH was calculated as the
change in pH from an initial 6.05 which was
the pH of the MRS broth at the time of
inoculation (0 h).
Production of α-amylase
To test for α-amylase production, a single
streak of a test Enterococcus, Lactobacillus
or Pediococcus culture was made on
modified MRS agar plates that did not
contain glucose, but instead contained 0.2%
89
Overnight cultures of Lactobacillus,
Enterococcus and Pediococcus isolates were
spotted on MRS agar plates containing 30
mM hematin. The plates were incubated at
37ºC overnight, after which the catalase test
was carried out by dropping a few drops of a
3% H2O2 solution on each colony. A
positive result was recorded when gas
production was evident by the formation of
bubbles from the colonies.
Tannin degradation by
controlled fermentation
starter-culture
To study the influence of starter cultures
on tannins degradation in fermented
sorghum
dough,
laboratory-scale
fermentation was carried out. This process
was controlled by adding an inoculum of
selected LAB isolates at the onset of
fermentation to the non-sterile ingredients.
In this test, five batches were prepared and
inoculated separately using the following
strains: A; spontaneously fermented batch
(control fermentation), B; Lactobacillus sp.
strain SH1 isolated from sorghum dough, C;
Enterococcus sp. strain FM2 isolated from
Fermented milk, D; Pediococcus sp. strain
C1 isolated from cheese, and E;
Enterococcus strain BFE 2206 (Tannase
producing positive control). The effect of
these starter cultures on tannin content
reduction was tested at intervals of 0h, 6h,
Res. J. Appl. Sci. Vol., 2(3): 88-100, 2015
12h, 24h and 36h. The tannin content was
estimated following the method described
by Price et al. (1987).
Results and Discussion
Phenotypic
characterization
and
distribution of LAB in Sudanese fermented
foods
In this study, 25 presumptive LAB
isolates were obtained from six Sudanese
fermented foods. The results of the
phenotypic characterization of LAB isolates
tested are shown in Table 1. The results
showed that all isolates were Gram-positive,
catalase-negative, nonendospore- forming,
and produced acid without the production of
gas from glucose. Among them, 40% (10
isolates) were rods, which occurred either
singly or in pairs, unable to grow in the
presence of 18% NaCl, or at pH 9.6, some of
which were unable to grow in the presence
of 6.5% NaCl, or at 45°C when tested in
MRS broth. These isolates were assigned to
the genus Lactobacillus. Whereas, 44% (11
isolates) were cocci that occurred as single
or in pairs with elongated, coccoid cell
morphology, and which were able to grow in
the presence of 6.5% NaCl, at pH 9.6, at
45°C and at 10°C in MRS broth. These
cocci were considered to constitute
enterococci. While, 16% (4 isolates) were
cocci which occurred in pairs or tetrads,
unable to grow in the presence of 18%
NaCl, or at pH 9.6, and able to grow in the
presence of 6.5% NaCl, at 45°C in MRS
89
broth. These cocci were identified as
pediococcal strains. In addition, these cocci
exhibited a well-rounded cell morphology
typical of the pediococci while other LAB
cocci such as enterococci and leuconostocs
exhibited a more elongated or coccoid cell
morphology. These findings indicated that
the dominant LAB strains responsible for
the fermentation process in the Sudanese
fermented foods were belong to the genus
Lactobacillus,
Enterococcus
and
Pediococcus. These genera are the most
frequently isolated genera of LAB that
associated with various Sudanese fermented
foods (Elyas et al., 2015; Saeed et al., 2014;
Yousif, 2003). The distribution of the
isolated strains in the tested Sudanese
fermented foods is presented in Table 2. The
results revealed that five isolates (50%) of
the isolated Lactobacilli were isolated from
mish, two isolates (20%) were from
sorghum dough, two isolates (20%) were
from pickles and remaining one isolate
(10%) was from sausage. Whereas, seven
isolates (64%) of Enterococci were isolated
from sausage, two isolates (18%) were from
fermented milk, one isolate (9%) was from
pickles, and one isolate (9%) was from
cheese. While, three isolates (75%) of
Pediococci were isolated from cheese and
remaining one isolate (25%) was originated
from fermented milk. Previous studies on
the distribution of LAB in Sudanese
fermented foods showed a similar trend of
distribution (Elyas et al., 2015; Saeed et al.,
2014; Yousif, 2003).
Res. J. Appl. Sci. Vol., 2(3): 88-100, 2015
Table 1. Phenotypic characterization of the isolated LAB from various Sudanese fermented
foods.
SH: Sorghum dough, C: Cheese, P: Pickles, SA: Sausage, M: Mish, FM: Fermented Milk.
Table 2. The distribution of genera of LAB isolated from different Sudanese fermented foods.
Isolated genera
Fermented Food
Lactobacillus
Enterococcus
Pediococcus
Sorghum (SH)
a
2 (20%)
-
-
Pickles (P)
2 (20%)
1 (9%)
-
Cheese (C)
-
1 (9%)
3 (75)%
Yoghurt (Y)
-
2 (18%)
1 (25%)
Mish (M)
5 (50%)
-
-
Sausage (SA)
1 (10%)
7 (64%)
-
Total
10 (40%)
11 (44%)
4 (16%)
a
no. of isolates, -, not detected, (%): percentage of isolates from different sources
89
Res. J. Appl. Sci. Vol., 2(3): 88-100, 2015
Technological
isolates
characteristics
of
LAB
The purpose of this study was to select
microorganisms associated with fermented
foods commonly consumed in Sudan as
possible candidates for starter culture
strains. To achieve that, 25 LAB isolates
were investigated for their relevant and
significant technological characteristics such
as high acidifying activity, production of αamylase, haeme-dependant catalase and
tannin-degrading abilities.
Acidifying Activity of the isolated LAB
Tolerance to acidity, bile and pancreatin
in vitro are expected to predict the survival
of a strain in the conditions encountered in
the gastrointestinal tract (Rubio et al., 2014).
Therefore, acid production and tolerance to
the high acidity environment is one of the
central roles in the selection of LAB as
probiotic and or starter culture. In this sense,
the acidifying ability of LAB isolated from
various Sudanese fermented foods was
evaluated. The results of acidifying activity
of the isolated LAB are depicted in three
figures (figure 1, 2, &3). The results
showed that after 6 h incubation Enterococci
isolates differed in their ability to reduce the
pH of the MRS broth (Fig. 1). The strains
SA6 and SA7 were slow acidifiers initially
(6 h) but acid production these isolates were
enhanced later (12 h) where they finally
accumulated enough acid to reduce pH to
2.2 and 2.02, respectively. Strains SA1,
SA2, SA3 and SA4 were faster initially, and
the ∆ pH (6 h) was 1.17, 1.12, 1.3 and 1.3,
respectively. In addition, the ∆pH (24 h) was
< 1.0 for 71% of the strains. Strikingly,
these findings demonstrated that Enterococci
89
isolates (SA1, SA2, SA3 and SA4) are very
efficient in reducing the pH of the MRS
media in the first 12 h to levels lower than
2.5. These results were not in agreement
with that found by Durlu-Ozkaya et al.,
(2001) who reported that, the acidifying
abilities of Enterococci strains at 30ºC were,
in general very low and cultures lowered the
pH of milk to < 5.0 after 24h of incubation.
Moreover, previous reports have indicated
the rapid acidification ability of Enterococci
(Kostinek et al., 2007); however, the pH
reduction was very low (pH > 5.0)
compared to that found in the present study
(pH < 2.5). The great acidifying potential
and in the meanwhile tolerance to lower pH
condition of the isolated Enterococcus
strains may pave the way for their
application as probiotic strains in starter
cultures for the preparation of various
functional foods. The acidifying activity of
Lactobacilli strains isolated from different
fermented foods is shown in figure 2. The
result shows the difference among the
Lactobacilli in their ability to reduce the pH
of the MRS broth initially. Strain M5 being
the slowest acidifier with ∆ pH 0.16 (6h).
Nevertheless, the acidifying ability of all
Lactobacillus strains after 12h and 24h
incubation were similar and ∆ pH ranged
between 1.68 to 1.97 (12h) except SH1, SH2
and M5 which had ∆ pH 2.27, 2.27 and 2.02
respectively. A similar trend in the
acidifying activity of Lactobacilli was
observed by Durlu-Ozkaya et al. (2001) who
reported that Lactobacillus strains differed
in their ability to reduce the pH of milk
initially (6 h). However, after 24 h
incubation the ∆pH (24 h) of the strains
were similar and ranged between 1.0 and
1.4.
Res. J. Appl. Sci. Vol., 2(3): 88-100, 2015
Figure 1. Acidification Activity of Enterococcus Isolated from
Different Fermented Foods
2.5
2
Tim e(h)
1.5
6
pH
∆ pH
12
24
1
36
0.5
0
SA:Sausage
SA1
C:Cheese
FM:Fermented milk
P:Pickle
SA2
SA3
SA4
SA5
SA6
SA7
C1
FM1
FM2
P1
Enterococcus Isolates
Figure 1. Acidifying activity of Enterococcus strains isolated from different Sudanese
fermented foods.
SA:
Sausage,Activity
C: Cheese,
FM: Fermented
P: Pickles.
Figure 2.
Acidification
of Lactobacillus
IsolatedMilk,
from Different
Fermented Foods
2.5
2
Time(h)
1.5
6
∆ pH
pH
12
24
1
36
0.5
SH:Sorghum
P:Pickle
M:Mish
SA:Sausage
0
SH1
SH2
P2
P3
M1
M2
M3
M4
M5
SA8
Lactobacilllus Isolates
Figure 2. Acidifying activity of Lactobacillus strains isolated from different Sudanese fermented
foods. SH: Sorghum dough, P: Pickles, M: Mish, SA: Sausage.
Badis et al. (2004) reported that the
acidifying ability of LAB isolated from raw
goat milk of four Algerian races were high
after 18 h. Yousif (2003) found that
acidifying activities of Lactobacilli were
89
almost similar among all strains, were they
initially had ∆pH of 1.5 after 12 h
incubation and remained constant until 36 h.
The acidifying activity of Pediococcus
isolates presented in Figure 3. The results
Res. J. Appl. Sci. Vol., 2(3): 88-100, 2015
showed that Pediococcus isolates differed in
evident from the current study that the
their ability to reduce the pH in MRS broth
Pediococcus strains proved to be fast
initially. All strains had initially slow
acidifiers
than
Lactobacillus
and
acidifying abilities having a ∆pH between
Enterococcus isolates. For LAB strains to
0.29 and 0.53. With the exception of strain
have a beneficial effect on intestine health,
FM3 that had a ∆pH 1.08 after 6 h
they need to be able to survive low acidic
incubation. However, after 12 h incubation,
conditions (Liu et al., 2013). Previously,
Pediococcus isolates had a high ∆pH,
Solieri et al. (2014) reported that the critical
ranging between 2.13 to 2.21 with the
limit of survival under exposure to acidic
exception of FM3, which showed relatively
conditions was pH 2.0, which was effective
lower ∆pH value towards the end of
in completely inhibiting the survival of
incubation time (36 h). These findings
almost all the strains. However, likely in the
agreed with that reported by Sulma et al.
current study some isolates of Enterococci,
(1991) who stated that the total acidPediococci and Lactobacilli showed great
producing bacteria attained their highest
acidifying potentiality and thus they could
counts by 18h, and their numbers declined
be used as an efficient starter and probiotic
as the pH of Figure
the batter
decreased.
It
is
cultures.Isolated from Different
3. Acidification Activity of Pediococcus
Fermented Foods
2.5
2
Tim e(h)
1.5
6
∆pH
pH
12
1
24
36
0.5
0
C:Cheese
FM:Fermented milk
C2
C3
C4
FM3
Pediococcus Isolates
Figure 3. Acidifying activity of Pediococcus strains isolated from different Sudanese fermented
foods. C: Cheese, FM: Fermented Milk.
Production of α-amylase and haeme-dependent catalase
The results of production of α-amylase
and
haeme-dependent
catalase
by
Enterococcus,
Lactobacillus
and
Pediococcus isolates are shown in figure 4.
The findings indicate that none of the
isolates in this study produced α-amylase.
This was not surprising because most of the
LAB in the current study were isolated from
89
non-or low starch-containing foods.
Previously, Kostinek et al. (2005) reported
that none of the predominant LAB strains
isolated from fermented cassava showed αamylase activity. These results also confirm
finding reported by Yousif (2003) who
found that none of the LAB strains isolated
from Hussuwa produced α-amylase. Alpha-
Res. J. Appl. Sci. Vol., 2(3): 88-100, 2015
amylase activity is known to improve bulk
dietary properties of lactic cereal gruels by
improving
the
viscosity/concentration
relationship (Lorri & Savenberg, 1993).
Most LAB, with the exception of the αamylase producing L. amylovorus and L.
amylophilus (Hammes & Vogel, 1995) are
known to be non-starch degrading. Haemedependent catalase is important in meat
fermentations because it avoids the
generation of off colours on its surface. The
haeme-dependent catalase activity of the
LAB isolated from different Sudanese
fermented foods is shown in figure 4. The
results revealed that all isolates of
Lactobacillus,
Enterococcus
and
pediococcus showed positive haemePercentage
Positive
dependant catalase Figure
activity4.when
cultivated
on MRS plates with haematin. This confirms
results reported by (Yousif, 2003) who
found that all Lactobacilli and Enterococci
strains and 71% of Pediococci isolated from
Hussuwa showed positive haeme-dependant
catalase activity when cultivated on MRS
plates with haematin. Haeme-dependant
catalase activity in LAB is a desirable
property that can prevent flavor, and color
defects in fermented foods thus improve
their sensory quality. This character is
relevant if a starter culture is to be used to
ferment meat-containing foods, where
haeme is abundant. Strikingly, the isolated
LAB strains in the present study could be
used as starter culture for the preparation of
meat-based fermented foods with constant
Strains
LAB
for the color and flavor.
sensory from
quality
especially
Technological Characteristics Tested
100
90
80
70
60
%
50
40
30
20
10
0
Alpha amylase
haeme-dependant catalase
Technological Characteristics
Lactobacilllus
Enterococcus
Pediococcus
Figure 4. Percentage of positive LAB isolates for the technological properties such as alpha
amylase and haeme-dependent catalase activities.
89
Res. J. Appl. Sci. Vol., 2(3): 88-100, 2015
Effect of starter culture controlled
fermentation on tannin Content
Most cereal-based diets have a poor
bioavailability of nutrients due to the
presence of antinutritional factors such as
phytases, polyphenols, and tannins. These
antinutrients bind readily with proteins and
minerals to form indigestible complexes.
However, during fermentation some
bacterial enzymes such as phytase and
tannase degrade these complexes thereby
releasing minerals and proteins and
accordingly improving the nutritional
quality of fermented foods. Thus, reduction
of this antinutritional factor is one of the
important technological properties used for
selection of probiotic and/or starter LAB.
With this in mind, an evaluation of tannin
degradation during fermentation of sorghum
flour was carried out. The results on the
tannin content of sorghum batches
fermenting using starter culture are shown in
figure 5. The tannin content on the control
batch (A) dropped from 1.7% to 0.6%
during the first 6 h of fermentation. This was
the lowest content in all the batches and
remained constant for the next 12 to 24 h.
By 36 h, it reached approximately 0.4%. The
Lactobacillus fermented batch (B) and the
batch fermented using positive control (E)
showed a similar pattern in the degradation
of tannin, where the tannin content was
reduced to 0.9% and 1%, respectively in the
first 6 h. Tannin content in both batches was
significantly reduced and reached about
0.3% by 36h. Enterococcus fermented batch
89
(C), and Pediococcus fermented batch (D)
showed a low decrease in tannin content
reaching 1% in 24h of fermentation and
further dropping about 0.8% at 36 h
fermentation. The control batch had the
highest reduction effect on tannin content in
the first 6h and remained low throughout the
fermentation.
This may be due to the combined effect
of all microbes responsible for the
fermentation. The Lactobacilli strain showed
the highest ability to degrade tannin from
the beginning compared to the other two
LAB strains and was comparable to the
positive control (Enterococcus strain BFE
2206). The results obtained in this study
were similar to those obtained by Idris
(2004) who found that fermentation for 14 h
caused an extremely significant decrease in
tannin for the two sorghum cultivars. Our
results also agree with that obtained by
Obizoba and Atii (1994) who found that a
much greater decrease in tannin content for
fermented sorghum seeds. Tannins bind
readily with proteins to form indigestible
complexes
(White,
1957).
Tannase
significantly breaks the galloyl ester bonds
of tannins, thereby inhibiting their proteinbinding properties (Bhat et al., 1998). Thus,
the tannase production would be a desirable
trait if the isolates were to be selected as
starter cultures. The role played by these
isolates that are capable of hydrolyzing
tannin is crucial in increasing the availability
of proteins and thus improving the
nutritional value of the food products.
Res. J. Appl. Sci. Vol., 2(3): 88-100, 2015
Figure 5. Tannin Content in Different Sorghum Batches Fermented
using Selected LAB Strains
1.8
1.6
Fermented
Sorghum
Batches
A
1.4
1.2
1
B
Tannins
0.8
Content
(%)
0.6
C
D
E
0.4
0.2
0
A:Control
0
6
12
18
24
30
36
42
B:Lactobacillus
Tim e (h)
C:Enterococcus
D:Pediococcus
Figure 5. Reduction of tannin content of different sorghum batches during the fermentation with
E:Positive
control LAB isolate. A: Control, B: Lactobacillus, C: Enterococcus, D: Pediococcus, E:
the selected
positive control.
Conclusion
References
In the current study, twenty-five strains
of LAB were isolated from different
Sudanese fermented foods composed of
44% Enterococci, 40% Lactobacilli and 16%
Pediococci strains. The isolated LAB has
many important technological properties
such acidification ability, acid tolerance,
haeme-dependant catalase, and tannin
degradation ability. There technological
properties are different depending on the
LAB strains, for example, Pediococcus
isolates had a highest acidification activity,
whereas, Lactobacillus strains had the
highest ability of degrading tannin during
fermentation compared to the other isolates.
Strikingly, some isolates demonstrated good
technological properties and thus they could
potentially be applied in the food industry as
a starter and/or probiotic cultures. Further
research shall specifically address the
molecular identification and functional
characterization of these potential isolates.
88
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