https://doi.org/10.52973/rcfcv-e34453
Received: 15/05/2024 Accepted: 01/07/2024 Published: 19/10/2024
1 of 9
Revista Científica, FCV-LUZ / Vol. XXXIV, rcfcv-e34453
ABSTRACT
The purpose of this study is to evaluate the antimicrobial properties
of Aloe vera Gel (AVG) and Aloe vera Extract (AVE). In the context
of food safety, the potential use of these natural products as
food preservatives and their effects at the microbial level have
been the primary focus. As part of the study, AVG and AVE were
prepared in different concentrations (1%, 2%, 3%, 4%, and 5% w/v).
The microorganisms used in the tests included Salmonella spp.,
Staphylococcus aureus, Escherichia coli, Bacillus subtilis subsp.
spizizenii, Candida albicans, and Aspergillus niger. Microbiological
analyses were conducted in accordance with ISO standards, and
the microbial loads were evaluated at different dilutions. The data’s
statistical analysis was carried out using the Wilcoxon Signed Rank
Test, Nonparametric Friedman Test, and Two–Way ANOVA. Both
forms of AVG and AVE were found to be effective against certain
tested bacteria and fungi. Specically, the gel form of AVG showed
effectiveness against B. subtilis and E. coli, while the extract form
was ineffective against these microorganisms. Statistical analyses
indicated that time is a significant factor in the antimicrobial
effectiveness of AVG and AVE. The study presented ndings that
support the potential use of AVG and AVE as food preservatives.
Key words: Aloe vera gel; Aloe vera extract; biological activity;
natural food additives
RESUMEN
El propósito de este estudio es evaluar las propiedades antimicrobianas
del gel de Aloe vera (AVG) y el extracto de Aloe vera (AVE). En el
contexto de la seguridad alimentaria, el enfoque principal ha sido
el uso potencial de estos productos naturales como conservantes
de alimentos y sus efectos a nivel microbiano. Como parte del
estudio, se prepararon AVG y AVE en diferentes concentraciones
(1, 2, 3, 4 y 5% p/v). Los microorganismos utilizados en las pruebas
incluyeron Salmonella spp., Staphylococcus aureus, Escherichia coli,
Bacillussubtilis subsp. spizizenii, Candida albicans y Aspergillus niger.
Los análisis microbiológicos se realizaron de acuerdo con las normas
ISO y las cargas microbianas se evaluaron en diferentes diluciones.
El análisis estadístico de los datos se realizó mediante la prueba de
rangos con signos de Wilcoxon, la prueba no paramétrica de Friedman
y el ANOVA bidireccional. Se descubrió que ambas formas de AVG
y AVE eran efectivas contra ciertas bacterias y hongos probados.
Especícamente, la forma de gel de AVG mostró efectividad contra B.
subtilis y E. coli, mientras que la forma de extracto fue inecaz contra
estos microorganismos. Los análisis estadísticos indicaron que el
tiempo es un factor importante en la ecacia antimicrobiana de AVG
y AVE. El estudio presentó hallazgos que respaldan el uso potencial
de AVG y AVE como conservantes de alimentos.
Palabras clave: Gel de Aloe vera; extracto de Aloe vera; actividad
biológica; aditivos alimentarios naturales
Analysis of biological activities of Aloe vera gel and extract used as the
potential use in natural food additives
Análisis de las actividades biológicas del gel y el extracto de Aloe vera
utilizados como posibles aditivos alimentarios naturales
Nuray Gamze Yörük
University of Dokuz Eylül, Faculty of Veterinary Medicine, Department of Food Hygiene and Technology. İzmir, Türkiye.
*Corresponding author: nuraygamzeyoruk@gmail.com
1 2 3 4 5
0.0
0.5
1.0
1.5
2.0
2.5
3.0
log. reduction
Concentration of
Aloe vera
(w/v %)
Staphylococcus aureus
Salmonella
spp.
Bacillus subtilis
subsp.
spizizenii
Escherichia coli
Candida albicans
and
Aspergillus niger
1 2 3 4 5
−0.5
0.0
0.5
1.0
1.5
2.0
2.5
3.0
log. reduction
Concentration of
Aloe vera
(w/v %)
Staphylococcus aureus
Salmonella
spp.
Bacillus subtilis
subsp.
spizizenii
Escherichia coli
Candida albicans
and
Aspergillus niger
FIGURE 1. Eects of AV gel (A) and extract (B) on the microorganisms according
to concentrations (1, 2, 3, 4, and 5% w/v)
A
B
Aloe vera gel and extract used as natural food additives / Yörük ____________________________________________________________________
2 of 9
INTRODUCTION
The earliest record of the use of Aloe vera (AV) (Aloe barbadensis
Miller) dates back to approximately 2200 BC, found on clay tablets with
Sumerian hieroglyphs, where it was used as a laxative. The term Aloe
originates from the Arabic word ‘alloeh’, which means a bright bitter
substance, and Vera comes from the Latin word ‘verus’, meaning true
[1]. Greek researchers named the AV plant as the universal panacea
two thousand years ago, while Egyptian researchers called it the
plant of immortality [2].
In modern times, food safety, being one of the most basic needs of
people, also holds critical importance for health. With technological
advancement, numerous chemical food additives are used to prevent
food spoilage and extend shelf life. Due to the negative effects and
potential carcinogenicity of these food additives accumulating in the
body over time, consumers are increasingly turning to organic foods.
Consequently, many natural antimicrobial and antioxidant agents are
becoming popular. Aloe vera is recognized as one of these natural
antimicrobials [3]. AV leaves primarily consist of two components:
latex and gel [4]. AV latex (also known as Aloe extract or juice) is a bitter,
yellow liquid that comes from pericyclic tubules beneath the leaf’s
epidermis. AV latex constitutes 20 to 30% of the total leaf weight, is
rich in phenolic compounds, and has antibacterial properties against
Gram–positive bacteria [4, 5, 6]. The four main C–glycosyl components
of AV latex are Aloesin; Aloin A, Aloin B, and Aloeresin A [7].
On the other hand, AV gel is a sticky, colorless gel derived from
parenchymatous cells in fresh leaves, accounting for 70% to 80% of
the leaf weight [8]. Polysaccharides in AV gel consist of Polymannan
chains containing signicantly more mannose than glucose [8, 9, 10,
11, 12]. The presence of bioactive components providing antioxidant
properties and agents like mannans, anthraquinone, C–glycoside, and
lectin in AV leaves have made aloe vera popular in the food industry
[13]. AV contains numerous molecules including anthraquinone
glycosides, polyhexoses, mannose, alkaloids, phenolic compounds,
phytosterols, lectins, and vitamins (vitamins A, B
1
, B
2
, B
4
, B
6
, B
12
, and
– tocopherol) [14, 15, 16]. Due to its anthraquinone content, AV has
antibacterial, antiviral, and antifungal activity [17, 18, 19]. Due to its
antimicrobial properties, AV has been used in various food products
such as yogurts, candy, ice cream, jams, instant tea granules, and
soft drinks [20, 21]. The frequent use of AV gel and AV extract as
a preservative in food products, which are continuously ingested
into our bodies, suggests the need to investigate the effect of this
preservative. However, this study focuses not so much on the benets
and harms of food preservatives, but rather on understanding how
protective they are against contaminants with high toxicity. The effect
of food preservatives at the microbial level is deemed important as
it also indicates how far fungal and microbial contaminants in food
can be removed. Based on these reasons, the purpose of this study
is to evaluate the antimicrobial ecacy of AV gel and AV extract.
MATERIALS AND METHODS
In this study, natural and preservative–free commercial Aloe Vera
Gel (AVG) (FOREVER®, 1 liter) and Aloe Vera Extract (AVE) (Nurbal
Healing®50g) food supplements were utilized.
Preparation for biological activity analysis of AV Gel and AV Extract
To evaluate the antimicrobial properties of AVG and AVE, nutrient
broth (NB) (LAB M–LAB 068, A Neogen Company, UK) containing AVG and
AVE dilutions of 1, 2 3, 4, and 5% (w/v) were prepared. For bacteria and
fungi, samples were incubated at 37°C (Nüve EN 055, Türkiye) for 24–48
hours (h) and 25°C for 120 h, respectively. Meanwhile, microbiological
analyses of the samples were conducted at the initial, 24, 48, 72, 96,
and 120
th
h, in accordance with ISO standards. The antimicrobial test
microorganisms included Salmonella spp. (550 cfu·g
-1
) (American Type
Culture Collection® (ATCC) 14028); coagulase positive Staphylococcus
(550 cfu·g
-1
) (National Culture Type Collection® England (NCTC) 6571);
Escherichia coli (550 cfu·g
-1
) (NCTC® 10788); Bacillus subtilis subsp.
spizizenii (550 cfu·g
-1
) (NCTC® 10400); Candida albicans (550 cfu·g
-1
)
(National Collection of Pathogenic Fungi (NCPF) 3179) and Aspergillus
niger (550 cfu·g
-1
) (ATCC® 16404). C. albicans and A. niger were maintained
at 25°C (Binder KB 053, Germany) for 72 h in 200 mL of NB, and other
microorganisms were incubated at 37°C (Nüve EN 055, Türkiye) for 24 h.
Preparation of 1, 2, 3, 4, and 5% dilutions of extract and gel
The dilutions of AV gel and AV extract were prepared with nutrient
broth (NB) in concentrations of 1, 2, 3, 4, and 5% (w/v). To achieve
sterile mixtures, these dilutions were autoclaved to ensure sterility
(Hirayama® HG80) at 121°C for 15 min. Fresh cultures of Salmonella
spp., coagulase positive Staphylococcus, E. coli, and B. subtilis were
added to the AVG and AVE mixtures prepared in NB at these ve
different concentrations and incubated at 37°C (Nüve EN 055, Türkiye)
for 24 h. Fresh cultures of C. albicans and A. niger were introduced
and incubated at 25°C (Binder KB 053, Germany) for 72 h. The load of
each microorganism in the control group was determined for each
dilution prior to each analysis (FIG. 1).
0 24 48 72 96 120
7.5
8.0
8.5
9.0
9.5
Estimated Marginal Means
Hours
log own load
log 1%
log 2%
log 3%
log 4%
log 5%
FIGURE 2. Estimated Marginal Means of Staphylococcus aureus (Aloe Vera Extract)
_____________________________________________________________________________Revista Cientifica, FCV-LUZ / Vol. XXXIV, rcfcv-e34453
3 of 9
Microbiological Analysis of Samples
To evaluate the bacterial and fungal load, 1 mL of microorganism
enriched with nutrient broth (NB) was taken and diluted with sterilized
TPS (LAB M–LAB 204, Neogen Culture Media, UK) from 10
-1
to 10
-10
. The
number of coagulase positive Staphylococcus strains was determined
by cultivating them on Baird Parker agar (BPA; sterile NCM0200A,
Neogen Culture Media, USA) using the spread plate method, in
accordance with the ISO 6888–1 standard. Colony count results were
obtained after incubation for 48 h at 37°C (Nüve EN 055, Türkiye) [22].
Salmonella spp. were cultured on Xylose Lysine Deoxycholate (XLD)
agar (NCM0021A, Neogen Culture Media, USA), which was sterilized
by boiling three times in a microwave (Beko® Intellowave MD 1593),
and the quantity of microorganisms (cfu·g
-1
) was determined by the
spread plate method. In accordance with the ISO 6579–1 standard,
0.1 mL of inoculation was cultured on XLD agar (NCM0021A, Neogen
Culture Media, USA) under aseptic conditions using the spread plate
method. The colony count was obtained after 24 hours of incubation
at 37°C (Nüve EN 055, Türkiye) [23]. The cultivation carried out by
the pour plate method on TBX agar (LAB M–Neogen Culture Media
NCM1001A HarlequinTM TBGA, UK) sterilized by autoclaving for 15 min
at 121°C yielded the number of E. coli. Parallel cultivation on TBX agar
under aseptic conditions using the pour plate method was performed
with 0.1 mL solution in accordance with the ISO 16649–2 standard.
The colony count results were obtained after 24 h of incubation at
41.5°C (Binder KB 115, Germany) [24].
Parallel cultivation of B. subtilis subsp. spizizenii samples was
conducted on Plate Count Agar (PCA) (NCM 0010A, Neogen Culture
Media, USA) using the pour plate method with 1 mL of solution in
accordance with the ISO 4833–1 standard. The colonies were counted
after 72 h of incubation at 30°C (Binder KB 053, Germany) [25].
To determine C. albicans and A. niger counts of samples, parallel
cultivation was performed on DRBC agar (LAB M–LAB217, A Neogen
Company, UK) using the spread plate method. Parallel cultivation
on DRBC agar was performed under aseptic conditions using the
spread plate method with 0.1 mL of solution in accordance with the
ISO 21527–1 standard. Mold and yeast counts were determined after
ve days of incubation at 25°C (Binder KB 053, Germany) [26]. (FIG. 1).
Statistical analysis
In the study, the microbiological analysis results of the ecacy
of AVG and AVE were statistically evaluated by the Wilcoxon
Signed Rank Test was used for binary (dependent) comparisons
and the Nonparametric Friedman Test was employed for multiple
comparisons. The effect of AV’s gel and extract forms against bacteria
and fungi was examined according to the concentrations of AVG and
AVE (1, 2, 3, 4, and 5% w/v) (FIG. 1). Statistical analyses were conducted
separately for each microorganism. Two–Way ANOVA analysis was
used to investigate the effect of AV extract at different concentrations
on the logarithmic results of the tested microorganisms. In the Two–
Way ANOVA model, the variable that is dependent was the log of
analysis results, the independent variable was the log percentage
value, and the covariate variable was time (hour).
RESULTS AND DISCUSSION
TABLE I presents the microbiological results for AVG and AVE
(A, B, C, and D). It was found that both forms of AV were effective
against S. aureus, C. albicans, and A. niger, but ineffective against
Salmonella spp. No signicant difference was observed in the load
(log) of Salmonella spp. depending on various AV concentrations. It
was determined that the gel form of AV was effective against E. coli
and B. subtilis, whereas the extract form was found to be ineffective.
The Friedman Test revealed a signicant difference between the
dilution rates of AV extract and the log values of S. aureus, C. albicans,
and A. niger (P<0.01). In contrast, no significant difference was
found between the dilution rates of AV extract and the log values of
Salmonella spp. (p = 0.091), E. coli, and B. subtilis (P>0.05).
According to the results of the Wilcoxon Signed Rank Test, there was
a signicant difference between the load (log) of S. aureus, C.albicans,
A. niger, B. subtilis, and the dilution rates (log) of AV extract (P<0.05).
Furthermore, a signicant difference was found between the E. coli
load (log) and the 1% value (log). There was no signicant difference
between the AV extract load (log) and values (log) at various dilution
rates for Salmonella spp. and B. subtilis (P>0.05). The Wilcoxon Signed
Rank Test used to determine if there was a signicant difference
between the microorganisms’ own load (log) and the values (log) at
different AV gel concentrations indicated a signicant difference
(P<0.05) between the own load (log) of C. albicans, A. niger, and
S.aureus, and the values (log) of AV gel concentrations. Additionally,
a signicant difference was detected between the own load (log) of
Salmonella spp. and the 1% (log) value.
Regarding the analysis results for S. aureus, while the log
percentages of Aloe vera extract created a signicant difference in
log values, the time variable had no effect. On the other hand, while
log percentages did not cause a signicant difference in the log values
of Aloe vera gel, time created a signicant difference.
When we performed the same analysis separately for log
percentages and time using the Kruskal Wallis Test, log percentages
resulted in a signicant difference for the log values of Aloe vera
extract, but time did not create a signicant difference. On the other
hand, both log percentages and time did not cause a signicant
difference in the log values of Aloe vera gel (FIGS. 2 and 3).
For Molds/Yeasts, while log percentages created a signicant
difference in the log values for Aloe Vera extract and gel, the effect
of the covariate variable time was not signicant (FIGS. 4 and 5).
TABLE I
Test statistics of microorganisms according to Friedman test Aloe Vera Extract and Aloe Vera Gel
(A and C) and Wilcoxon test Aloe Vera Extract and Aloe Vera Gel (B and D)
A: Test Statistics
1
Salmonella spp. Yeast/mould TMAB Escherichia coli Staphylococcus aureus
N 7 6 6 6 6
Chi-Square 27.158 9.495 15.773 8.61 5.101
df 5 5 5 5 5
Asymp. Sig. 0.000
b
0,091
c
0.008
b
0,126
c
0,404
c
1
: Friedman Test,
b
: signicant dierence (P<0.01),
c
: no dierence (P>0.05)
C: Test Statistics
1
Salmonella spp. Yeast/mould TMAB Escherichia coli Staphylococcus aureus
N 7 6 6 6 6
Chi-Square 21.81 10.902 18.561 8.301 12.067
df 5 5 5 5 5
Asymp. Sig. 0.001
b
0,053
c
0.002
b
0.14
c
0.034
b
1
: Friedman Test,
b
: signicant dierence (P<0.01),
c
: no dierence (P>0.05)
Pairwise comparison of the own loads of the microorganisms and concentrations
B: Test Statistics
1
1% 2% 3% 4% 5%
S. aureus Z -2,388
b
-2,371
b
-2,371
b
-2,414
b
-2,371
b
P 0.017 0.018 0.018 0.016 0.018
Salmonella spp. Z -0,734
b
-0,314
b
-0,943
c
-0,105
b
-0,314
b
P 0.463 0.753 0.345 0.917 0.753
Yeast/mould Z -2,201
b
-2,201
b
-2,201
b
-2,207
b
-2,201
b
P 0.028 0.028 0.028 0.027 0.028
TMAB Z -2,201
b
-1,992
b
-1,992
b
-1,992
b
-1,782
b
P 0.028 0.046 0.046 0.046 0.075
E. coli Z -2,201
b
-0,734
b
-0,524
b
-0,734
b
-0,943
b
P 0.028 0.463 0.600 0.463 0.345
1
: Wilcoxon Signed Ranks Test,
b
: Based on negative ranks,
c
: Based on positive ranks
Pairwise comparison of the own loads of the microorganisms and concentrations
D: Test Statistics
1
1% 2% % 3 4% 5%
S. aureus Z -2,384
b
-2,370
b
-2,366
b
-2,414
b
-0,507
b
P 0.017 0.017 0.018 0.016 0.612
Salmonella spp. Z -1,992
b
-0,105
b
-0,524
c
-1,153
b
-0,314
c
P 0.046 0.917 0.600 0.249 0.753
Yeast/mould Z -2,201
b
-2,201
b
-2,201
b
-2,201
b
-2,201
b
P 0.028 0.028 0.028 0.028 0.028
TMAB Z -0,943
b
-1,782
b
-1,572
b
-1,363
b
-1,782
b
P 0.345 0.075 0.116 0.173 0.075
E. coli Z -1,153
b
-0,314
b
-0,524
c
-0,524
c
-0,105
b
P 0.249 0.753 0.600 0.600 0.917
1
: Wilcoxon Signed Ranks Test,
b
: Based on negative ranks,
c
: Based on positive ranks
Aloe vera gel and extract used as natural food additives / Yörük ____________________________________________________________________
4 of 9
Regarding the Total Mesophilic Aerobic Bacteria (TMAB) counts,
while the log percentages did not create a signicant difference in
the log values of Aloe Vera extract, time had a signicant effect.
Conversely, the effect of AV concentrations and time on the log count
of TMAB was found to be signicant. When conducting the same
analysis separately for log percentages and time using the Kruskal
Wallis test, log percentages did not result in a signicant difference
for the log values of Aloe vera extract and gel, while time did create
a signicant difference (FIGS. 6 and 7).
0 24 48 72 96 120
8.0
8.5
9.0
9.5
Estimated Marginal Means
Hours
log own load
log 1%
log 2%
log 3%
log 4%
log 5%
0 24 48 72 96 120
5
6
7
8
9
10
11
12
Estimated Marginal Means
Hours
log own load
log 1%
log 2%
log 3%
log 4%
log 5%
0 24 48 72 96 120
5
6
7
8
9
10
11
12
Estimated Marginal Means
Hours
log own load
log 1%
log 2%
log 3%
log 4%
log 5%
0 24 48 72 96 120
8
9
10
11
12
Estimated Marginal Means
Hours
log own load
log 1%
log 2%
log 3%
log 4%
log 5%
0 24 48 72 96 120
9
10
11
12
Estimated Marginal Means
Hours
log own load
log 1%
log 2%
log 3%
log 4%
log 5%
FIGURE 3. Estimated Marginal Means of Staphylococcus aureus (Aloe Vera Gel)
FIGURE 4. Estimated Marginal Means of Yeast and Mould (Aloe Vera Extract)
FIGURE 5. Estimated Marginal Means of Yeast and Mould (Aloe Vera Gel)
FIGURE 6. Estimated Marginal Means of Total Mesophilic Aerobic Bacteria (Aloe
Vera Extract)
FIGURE 7. Estimated Marginal Means of Total Mesophilic Aerobic Bacteria (Aloe
Vera Gel)
_____________________________________________________________________________Revista Cientifica, FCV-LUZ / Vol. XXXIV, rcfcv-e34453
5 of 9
According to the analysis results for E. coli, while log percentages did
not cause a signicant difference in the log values of Aloe Vera extract
and gel, time did have a signicant effect. Again, when performing the
same analysis for log percentages and time using the Kruskal Wallis
test, log percentages did not create a signicant difference in the
log values of Aloe Vera extract and gel, while time did (FIGS. 8 and 9).
The results for Salmonella spp. showed that while log percentages
did not create a signicant difference in the log values of Aloe vera
extract and gel, time had a signicant effect. The Kruskal Wallis
test results for Salmonella spp. regarding log percentages and time
indicated that log percentages did not create a signicant difference
in the log values of Aloe vera extract and gel, while time did create a
signicant difference (FIGS. 10 and 11).
Bhat et al. [18] there was no mold–yeast growth in both the control
group and nuggets with added AV until the 14
th
d, and on the 21
st
d,
there was a signicant reduction in mold–yeast growth in nuggets
with added AV compared to the control group.
0 24 48 72 96 120
8
9
10
11
12
Estimated Marginal Means
Hours
log own load
log 1%
log 2%
log 3%
log 4%
log 5%
0 24 48 72 96 120
8
9
10
11
12
Estimated Marginal Means
Hours
log own load
log 1%
log 2%
log 3%
log 4%
log 5%
0 24 48 72 96 120
8
9
10
11
12
Estimated Marginal Means
Hours
log own load
log 1%
log 2%
log 3%
log 4%
log 5%
0 24 48 72 96 120
7
8
9
10
11
12
Estimated Marginal Means
Hours
log own load
log 1%
log 2%
log 3%
log 4%
log 5%
FIGURE 8. Estimated Marginal Means of Escherichia coli (Aloe Vera Extract) FIGURE 11. Estimated Marginal Means of Salmonella spp. (Aloe Vera Gel)
FIGURE 9. Estimated Marginal Means of Escherichia coli (Aloe Vera Gel)
FIGURE 10. Estimated Marginal Means of Salmonella spp. (Aloe Vera Extract)
Aloe vera gel and extract used as natural food additives / Yörük ____________________________________________________________________
6 of 9
According to Shahrezaee et al. [27], the total number of living
organisms in nugget dough and half–baked nuggets increased by
approximately 2 log cfu·g-1 after 6 d of cold storage post–production.
The same study also reported an initial decrease in microbial load in
nugget doughs containing 1.5 and 2.5% AV gel powder (AGP). However,
AGP did not prevent the increase in the total bacterial count during 6 d
of cold storage. According to the researchers 2.5 and 3.5% AGP at 4°C
cold storage effectively prevented coliform proliferation for up to 4 d,
while 1.5% AGP provided protection only for 2 d. Overall, they reported
that 3.5% AGP was ideal for preventing coliform contamination and
that there was no mold–yeast growth due to the effectiveness of
AGP as an antifungal. Serial dilutions of AV prepared by diluting by
1/10 signicantly inhibited the growth of S. aureus, and a moderate
AV concentration inhibited the growth of E. coli, Pseudomonas
aeruginosa, and Salmonella typhi.
Mandal et al. [11] stated that proteins in the AV structure were
powerful antifungals, which supports our ndings. Valverde et al.
[28] determined that TMAB and Mold–Yeast counts for table grapes
harvested in the control groups were 4.6 and 3.5 log cfu·g
-1
, respectively.
They investigated that mold–yeast counts in AV–treated grapes
decreased by 1.5 log cfu·g
-1
after 21 d at 20°C and 2.6 log cfu·g
-1
after
4 d of cold storage.
Sitara et al. [29] found that a 0.35% gel concentration of Aloe
Vera was antifungal, inhibiting A. niger by 24.29%, Aspergillus avus
by 9.26%, and Penicillium digitatum by 6.24%. According to Abdul
Qadir and colleagues [30], AV was effective against four pathogenic
bacteria: B. subtilis, S. aureus, Pasteurella multocida, E. coli, and fungi
such as A. avus, Rhizoctonia solani, A. niger, and Alternaria alternate.
Similar to our study, Jeevitha and colleagues [31] demonstrated that
AV had antifungal activity against C. albicans using minimum inhibitory
concentration and minimum fungicidal concentration tests.
In a study conducted by Alemdar and Agaoglu [6] AV juice had
antimicrobial effects against Mycobacterium smegmatis, Klebsiella
pneumoniae, Enterobacter faecalis, Micrococcus luteus, C. albicans,
and Bacillus sphericus. Another study investigated the antimicrobial
properties of AV gel against P. digitatum and B. subtilis. In vitro,
250mL·L
-1
of AV gel caused a 4 log cfu·g
-1
decrease in P. digitatum
and a 2 log cfu·g
-1
decrease in Botrytis cinerea [32].
_____________________________________________________________________________Revista Cientifica, FCV-LUZ / Vol. XXXIV, rcfcv-e34453
7 of 9
Consistent with the ndings of the current study, Shahat et al.
[33] reported in their antimicrobial ecacy studies with 24 different
medicinal plants in Saudi Arabia that four Gram–positive (B. cereus,
S. aureus, M. luteus, Micrococcus roseus) and four Gram–negative
(K. pneumoniae, Proteus vulgaris, Pseudomonas aeruginosa) were
resistant to the effect of these plants. In their studies on the
antibacterial activity of plant extracts widely consumed in Asia,
Alzoreky et al. [34] found that Gram–positive bacteria (S. aureus
and B. cereus) were less resistant than Gram–negative bacteria (E.
coli). In their study on the antimicrobial effects of 14 plant extracts
obtained from 13 plant species on 2 Gram–positive and 5 Gram–
negative microorganisms, Keleş et al. [35] determined that the most
sensitive microorganism to these plants was S. aureus, a Gram–
positive microorganism, and the most resistant microorganisms
were E. coli and K. pneumoniae, both Gram–negative microorganisms.
Similar to the ndings of the current study, Bilenler [36] found
that Gram–positive bacteria (S. aureus, S. hominis, S. warneri, S.
epidermidis, B. cereus, E. faecalis, Enterobacter spp., Streptococcus
spp., Salmonella spp., Shigella Flexner) were more sensitive than
Gram–negative bacteria to the antimicrobial effects of black mulberry.
It was also noted that black mulberry signicantly slowed the growth
of C. albicans. This was attributed to the fact that C. albicans is a
eukaryotic microorganism, unlike prokaryotic microorganisms.
Hayat et al. [37] investigated the antimicrobial effects of Aloe vera
extracts on Erwinia carotovora, E. coli, K. pneumoniae, Salmonella
typhi, B. subtilis, B. cereus, S. aureus, and C. albicans, nding that
the ecacy was higher on Gram–positive microorganisms due to
lipopolysaccharides in their cell walls. The greatest antimicrobial
effect was observed in the C. albicans studies [38, 39].
CONCLUSIONS
With the advancement of technology, cheaper and more practical
methods are being utilized to increase food diversity while ensuring
these foods meet appropriate quality standards. To achieve this,
chemical or artificial food additives are commonly used. These
substances are added in various forms as preservatives, stabilizers,
and emulsiers in different food classes, including ready–to–eat,
not–ready–to–eat, processed, unprocessed, and packaged foods (etc;
cheese, yogurt, sh, packet of raw chicken or meat…). However, it is
known that such substances can cause nutritional health problems
over time and sometimes lead to hereditary (hereditary anomalies,
reproductive issues, etc.) and metabolic (cancer, diabetes, liver
problems, etc.) complications. Consequently, there is an increasing
trend towards organic food or natural food additives to ensure quality
assurance in terms of taste, texture, and color in foods. It is imperative
to prioritize human health over food production and delivery.
The results obtained in the current study have demonstrated
that both AVG and AVE are effective against S. aureus, C. albicans,
and A. niger, and AVG is effective against E. coli. This indicates a
need for further research to establish the antibacterial properties
of Aloe vera in foods and its role in the food industry, as Aloe vera is
considered a natural antimicrobial agent in this study. It was found
that AVG and AVE effectively inhibited the growth of S. aureus, C.
albicans, and A. niger. Interestingly, these preparations were found
to be ineffective against Salmonella spp., suggesting a selective
antimicrobial action of Aloe vera components. The study did not
observe a signicant variance in the bacterial load of Salmonella
spp., indicating a consistent resistance pattern in this specific
microorganism. However, a notable ecacy of AVG, particularly
against E. coli and B. subtilis, was recorded, while AVE was found to
be less effective. This points towards a distinct inuence of the form
in which Aloe vera is applied. The study also underscored the critical
role of time in the antimicrobial effectiveness of Aloe vera products,
as seen in the Kruskal Wallis test results.
This pattern was consistent across different microbial species,
including molds/yeasts and Total Mesophilic Aerobic Bacteria (TMAB),
conrming the broad–spectrum antimicrobial nature of Aloe vera.
These results not only highlight the selective effectiveness against
certain microorganisms and the variance in response between AVG
and AVE but also suggest the potential for targeted applications in
controlling specic microbial threats.
Peer–reviewed
Externally peer–reviewed.
Funding support
There was no specic grant from a funding agency in the public,
commercial, or not–for–prot sectors for this research.
Conict of Interest
The author state that do not have any conicts of interest.
Ethics approval
Not required. Any of the author conducted no human or animal
studies in this article.
Consent for publication
Not required.
Compliance with ethical standards
There are no studies with human or animal subjects in this article.
BIBLIOGRAPHIC REFERENCES
[1] Borchers A, Teuber SS, Keen CL, Gershwin ME. Food safety.
Clin. Rev. Allergy Immunol. [Internet]. 2010; 39(2):95–141. doi:
https://doi.org/csfwbw
[2] Surjushe A, Vasani R, Saple DG. Aloe vera: a short review. Indian J.
Dermatol. [Internet]. 2008; 53(4):163–166. https://doi.org/bdpbmb
[3] Park YI, Jo TH. Perspectives of industrial application of Aloe
vera. In: Park YI, Lee SK, editors. New Perspectives on Aloe
[Internet]. Boston (MA, USA): Springer; 2006. p. 191–200. doi:
https://doi.org/chmh9b
[4] Wang H. Preparation and characterization of dual functional
antimicrobial (bio)degradable polymers [dissertation on the
Internet]. [Bayreuth (Germany)]: University of Bayreuth; 2016
[cited 15 Apr. 2024]. 142 p. Available in: https://goo.su/QaOn2Xd
[5] Boudreau MD, Beland FA. An evaluation of the biological and
toxicological properties of Aloe barbadensis (Miller), Aloe vera.
J. Environ. Sci. Health C [Internet]. 2006; 24(1):103–154. https://
doi.org/bxqtnr
Aloe vera gel and extract used as natural food additives / Yörük ____________________________________________________________________
8 of 9
[6] Alemdar S, Ağaoğlu S. Investigation of In vitro antimicrobial activity
of Aloe vera juice. J. Anim. Vet. Adv. [Internet]. 2009 [cited 24
Mar. 2024]; 8(1):99–102. Available in: https://goo.su/neph
[7] Boudreau MD, Beland FA, Nichols JA, Pogribna M. Toxicology and
carcinogenesis studies of a nondecolorized [corrected] whole
leaf extract of Aloe barbadensis Miller (Aloe vera) in F344/N rats
and B6C3F1 mice (drinking water study) [Internet]. Research
Triangle Park (NC, USA): Natl. Toxicol. Program, U.S. Department
of Health and Human Services; 2013. 266 p. NTP TR 577. Available
in: https://goo.su/9qpFsr
[8] Başyiğit Kılıç G, Bilecen Şen D, Alnakdalı D, Gülşen M. Aloe
Vera’nın gıda endüstrisinde kullanımı [The use of Aloe vera in
food industry]. Mühendislik Bilim. Tasar. Derg. [Internet]. 2020;
8(1):326–332. Turkish. https://doi.org/g8ng7k
[9] Gowda DC, Neelisiddaiah B, Anjaneyalu YV. Structural studies
of polysaccharides from Aloe vera. Carbohydr. Res. [Internet].
1979; 72:201–205. https://doi.org/cnkpxb
[10] Femenia A, Sánchez ES, Simal S, Rosselló C. Compositional
features of polysaccharides from Aloe vera (Aloe barbadensis
Miller) plant tissues. Carbohydr. Polym. [Internet]. 1999;
39(2):109–117. https://doi.org/dr7d24
[11] Mandal G, Das A. Structure of the D–galactan isolated from Aloe
barbadensis Miller. Carbohydr. Res. [Internet]. 1980; 86(2):247–
257. https://doi.org/bqz2r8
[12] Yaron A. Characterization of Aloe vera gel before and after
autodegradation, and stabilization of the natural fresh gel.
Phytother. Res. [Internet]. 1993; 7(7):S11–S13. https://doi.org/d3f9gn
[13] Rodríguez Rodríguez E, Darias Martin J, Díaz Romero C. Aloe
vera as a functional ingredient in foods. Crit. Rev. Food Sci.
Nutr. [Internet]. 2010; 50(4):305–326. https://doi.org/cdvfm4
[14] Hamman JH. Composition and applications of Aloe vera leaf gel.
Molecules [Internet]. 2008; 13(8):1599–1616. https://doi.org/d89tjn
[15] Mulay S, Borade A, Bele A, Khale A. Aloe vera – A review. Int. J.
Pharm. Phytopharm. Res. [Internet]. 2013 [cited 12 Jan. 2024];
3(3):203–211. Available in: https://goo.su/pgTrqG
[16] Nejatzadeh–Barandozi F. Antibacterial activities and antioxidant
capacity of Aloe vera. Org. Med. Chem. Lett. [Internet]. 2013;
3(5)1–8. https://doi.org/g4hrct
[17] Alves DS, Pérez–Fons L, Estepa A, Micol V. Membrane–related
effects underlying the biological activity of the anthraquinones
emodin and barbaloin. Biochem Pharm. [Internet]. 2004;
68(3):549–561. https://doi.org/fdswzx
[18] Bhat ZF, Kumar S, Kumar P. Effect of Aloe vera on the lipid
stability and storage quality of chicken nuggets. Nutr. Food
Sci. [Internet]. 2015; 45(1):54–67. https://doi.org/g8ng7m
[19] Çete S, Arslan NF, Yaşar A. Investigation of antimicrobial
effects against some microorganisms of Aloe vera and Nerium
oleander also examination of the effects on the xanthine oxidase
activity in liver tissue treated with cyclosporin. Gazi Univ. J. Sci.
[Internet]. 2010 [cited 23 Jan. 2024]; 18(3):375–380. English,
Turkish. Available in: https://goo.su/4UFie2Y
[20] Ahlawat KS, Khatkar BS. Processing, food applications and
safety of aloe vera Products: a review. J. Food Sci. Technol.
[Internet]. 2011; 48(5):525–533. https://doi.org/b4jfzj
[21] Steenkamp V, Stewart MJ. Medicinal applications and toxicological
activities of Aloe products. Pharm. Biol. [Internet]. 2007; 45(5):411–
420. https://doi.org/bbrnjp
[22] International Organization for Standardization. ISO 6888–1:1999.
Microbiology of food and animal feeding stuffs — Horizontal
method for the enumeration of coagulase–positive staphylococci
(Staphylococcus aureus and other species) — Part 1: Technique using
Baird–Parker agar médium. Geneva (Switzerland): ISO; 1999. 11 p.
[23] International Organization for Standardization. ISO 6579–1:2017.
Microbiology of the food chain — Horizontal method for the
detection, enumeration and serotyping of Salmonella — Part 1:
Detection of Salmonella spp. Geneva (Switzerland): ISO; 2017. 11 p.
[24] International Organization for Standardization. ISO 16649–2: 2001.
Microbiology of food and animal feeding stuffs — Horizontal method
for the enumeration of ß–glucuronidase–positive Escherichia coli —
Part 2: Colony count technique at 44°C using 5–bromo–4–chloro–3–
indolyl ß–D–glucuronide. Geneva (Switzerland): ISO; 2001. 8 p.
[25] International Organization for Standardization. ISO 4833–1:2013.
Microbiology of the food chain — Horizontal method for the
enumeration of microorganisms — Part 1: Colony count at 30˚C
by the pour plate method. Geneva (Switzerland): ISO; 2013. 9 p.
[26] International Organization for Standardization. ISO 21527–1:2008.
Microbiology of food and animal feeding stuffs — Horizontal
method for the enumeration of yeasts and moulds — Part 1:
Colony count technique in products with water activity greater
than 0,95. Geneva (Switzerland): ISO; 2008. 8 p.
[27] Shahrezaee M, Soleimanian–Zad S, Soltanizadeh N, Akbari–
Alaveh S. Use of Aloe vera gel powder to enhance the shelf life
of chicken nugget during refrigeration storage. LWT [Internet].
2018; 95:380–386. https://doi.org/g8ng7n
[28] Valverde JM, Valero D, Martínez–Romero D, Guillén F, Castillo
S, Serrano M. Novel edible coating based on Aloe vera gel to
maintain table grape quality and safety. J. Agric. Food Chem.
[Internet]. 2005; 53(20):7807–7813. https://doi.org/crfpqh
[29] Sitara U, Hassan N, Naseem J. Antifungal activity of Aloe vera gel
against plant pathogenic fungi. Pak. J. Bot. [Internet]. 2011 [cited 12
Mar. 2014]; 43(4): 2231–2233, Available in: https://goo.su/5X0K8N5
[30] Abdul Qadir M, Shahzadi SK, Bashir A, Munir A. Shahzad S. Evaluation
of phenolic compounds and antioxidant and antimicrobial activities
of some common herbs. Int. J. Anal. Chem. [Internet].2017;
2017(3475738):1–6. https://doi.org/f9w4j5
[31] Jeevitha T, Deepa K, Michael A. In vitro study on the anti–microbial
ecacy of Aloe vera against Candida albicans. African J. Microbiol.
Res. [Internet]. 2015; 12(40):930–937. https://doi.org/g8ng7p
[32] Castillo S, Navarro D, Zapata PJ, Guillén F, Valero D, Serrano
M, Martínez–Romero D. Antifungal ecacy of Aloe vera in vitro
and its use as a preharvest treatment to maintain postharvest
table grape quality. Postharvest Biol. Technol. [Internet]. 2010;
57(3):183–188. https://doi.org/dkv43z
_____________________________________________________________________________Revista Cientifica, FCV-LUZ / Vol. XXXIV, rcfcv-e34453
9 of 9
[33] Shahat AA, Mahmoud EA, Al–Mishari AA, Alsaid MS. Antimicrobial
activities of some Saudi Arabian herbal plants. Afr. J. Tradit.
Complement. Altern. Med [Internet]. 2017; 14(2):161–165. https://
doi.org/g8ng7q
[34] Alzoreky N, Nakahara K. Antibacterial activity of extracts from
some edible plants commonly consumed in Asia. Int. J. Food
Microbiol. [Internet]. 2003; 80(3):223–230. https://doi.org/dzttqh
[35] Keleş O, Ak S, Bakırel T, Alpınar K. Türkiye’de yetişen bazı
bitkilerin antimikrobiyel etkisinin incelenmesi [Screening of
some turkish plants for antibacterlal activity]. Turk. J. Vet. Anim.
Sci. [Internet]. 2001 [cited 12 Mar. 2024]; 25(4):559–565. Turkish.
Available in: https://goo.su/Ajy5z
[36] Bilenler T. Karadut meyvesinin antimikrobiyel aktivitesinin ve
bilesenlerinin belirlenmesi [Determination antimicrobial activity
and components of black mulberry fruit [master’s thesis].
[Malatya (Türkiye)]: Inonu University; 2010. 189 p. Turkish.
[37] Hayat MK, Kumar T, Ahmad N, Jan AS, Sajjad W, Faisal S, Gao BX,
Khan K, Rahman ZU, Abbasi BH. In vitro antimicrobial activity
of Aloe vera L. extracts against pathogenic bacteria and fungi.
Mycopath [Internet]. 2016 [cited 22 Jan. 2024]; 14(1–2):21–27.
Available in: https://goo.su/zZnr
[38] Kalemba D, Kunicka A. Antibacterial and antifungal properties of
essential oils. Curr. Med. Chem. [Internet]. 2003; 10(10):813–829.
https://doi.org/dwrqj2
[39] Prasetya AT, Mursiti S, Maryan S, Jati NK. Isolation and identication
of active compound on papaya plants and activities as antimicrobial
[Internet]. IOP Conference Series: Materials Science and
Engineering. 12
th
Joint Conference on Chemistry; 2017 Sep 19–20;
Indonesia. IOP Publishing Ltd; 2018. 7 p. doi: https://doi.org/g8ng7r