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Coffee industrial waste as a natural source of bioactive compounds with antibacterial and antifungal activities

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Coffee is one of the most popular and consumed beverages in the world, which leads to a high contents of solid residue known as spent coffee grounds (SCG). As is known, coffee beans contain several classes of health related chemicals, including phenolic compounds, melanoidins, diterpenes, xanthines and carotenoids which are associated with therapeutic and pharmaceutical effects, due to antimicrobial, antioxidant, anti-infectious and antitumour activities. Considering that this coffee industrial waste has no commercial value and are currently disposed as a solid waste or employed as fertilizers, we intend to highlight the use of SCG as a raw material with potential interest to the food and pharmaceutical industries. Moreover, this work seems to be valuable to promote the use of SCG as natural and an inexpensive food supplements or pharmaceutical additive. The phytochemical compounds content among the crude aqueous extracts of SCG followed this order: phenolics > flavonoids > carotenoids (mg/ g dry waste), respectively. Caffeine content found in SCG was ~ 0.82 g/ 100 g dry waste, 70 % lower than coffee roasting beans. Coffee ground extracts showed inhibition to S. aureus and E. coli growth for concentrations of 1.0 mg/ mL and a stronger inhibition was also observed against C. albicans, C. krusei and C. parapsilosis growth using lower concentration (0.5 mg/ mL).
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Coffee industrial waste as a natural source of bioactive compounds with
antibacterial and antifungal activities
C. Sousa1, C. Gabriel1, F. Cerqueira1, M.C. Manso1,2 and A.F. Vinha*,1,2
1 FP-ENAS (UFP Energy, Environment and Health Research Unit), CEBIMED (Biomedical Research Centre), University
Fernando Pessoa, Praça 9 de Abril, 349, 4249-004 Porto, Portugal
2 REQUIMTE/LAVQ/Dep. of Chemical Science, Faculty of Pharmacy, University of Porto, Rua Jorge Viterbo Ferreira,
228, 4050-313 Porto, Portugal
Coffee is one of the most popular and consumed beverages in the world, which leads to a high contents of solid residue
known as spent coffee grounds (SCG). As is known, coffee beans contain several classes of health related chemicals,
including phenolic compounds, melanoidins, diterpenes, xanthines and carotenoids which are associated with therapeutic
and pharmaceutical effects, due to antimicrobial, antioxidant, anti-infectious and antitumour activities. Considering that
this coffee industrial waste has no commercial value and are currently disposed as a solid waste or employed as fertilizers,
we intend to highlight the use of SCG as a raw material with potential interest to the food and pharmaceutical industries.
Moreover, this work seems to be valuable to promote the use of SCG as natural and an inexpensive food supplements or
pharmaceutical additive. The phytochemical compounds content among the crude aqueous extracts of SCG followed this
order: phenolics > flavonoids > carotenoids (mg/ g dry waste), respectively. Caffeine content found in SCG was ~ 0.82 g/
100 g dry waste, 70 % lower than coffee roasting beans. Coffee ground extracts showed inhibition to S. aureus and E. coli
growth for concentrations of 1.0 mg/ mL and a stronger inhibition was also observed against C. albicans, C. krusei and C.
parapsilosis growth using lower concentration (0.5 mg/ mL).
Keywords: Spent coffee grounds; Aqueous extracts; Natural antioxidants; Antibacterial activity; Antifungal activity.
1. Introduction
Coffee is a rich source of dietary antioxidants, and this property, coupled with the fact that it is one of the world’s most
popular beverages, has led to the understanding that coffee is a major contributor to dietary antioxidant intake. Natural
bioactive compounds from coffee industry by-products have been receiving increasing attention, having in view the
sustainability of the processes [1,2]. Spent coffee grounds (SCG) are a by-product generated during espresso beverages
or soluble coffee production. Food by-products are focus of great interest in scientific community, once they may
provide natural antioxidant and antimicrobial substances. In addition, valorization and re-use of food by-products
minimizes industry wastes, with higher impact in sustainability and economic concepts. Coffea Arabica (Arabica) and
Coffea canephora var. robusta (Robusta) are the two main species of the genus Coffea usually cultivated for
commercial production. Nowadays, Arabica accounts approximately 75 % of the world production and, is considered to
be favored to Robusta due to its milder and more flavorful taste, while Robusta is mostly used by the instant coffee
industry for the manufacturing of soluble coffee [3].
It is acknowledged that coffee beans contain several classes of natural health chemicals, such as phenolics,
melanoidis, diterpenes, xanthines, and vitamin precursors [4,5]. Considering their health beneficial, several studies
reported that the consumption of phenolic acids and flavonoids provide in vivo protection against free radical damage
and reduce the risk of degenerative diseases usually associated with oxidative stress [6,7]. Caffeine, the major xanthine
presented in coffee beans, is the most studied coffee component due of its well-established psychoactive effects and
promotion of energy metabolism [8]. Other compounds also provide health benefits, including carotenoids and
chlorogenic acids, which are formed by esterification of one molecule of quinic acid and one to three molecules of
trans-hydroxycinnamic acids, mainly caffeic, ferulic, and p-coumaric. In addition, the main chlorogenic acids present in
coffee are highly bioavailable, being easily absorbed and metabolized throughout the gastrointestinal tract [9].
Moreover, the indiscriminate use of antimicrobial agents resulted in the emergence of drug-resistant bacteria, fungi
and viruses. Various populations in developing countries are using natural plant products against infectious diseases by
accidental discovery, and trust in the benefit of their use. To overcome the increased resistance of pathogenic microbes,
researchers are using traditional knowledge as source of development of new drugs with high antimicrobiotic potential.
The use of phytochemicals as natural antimicrobial agents, commonly called “biocides”, is gaining popularity. There is
a growing interest among the medical proprieties of natural resources in terms of antibacterial activity. In the ongoing
search for better antibacterial compounds, plant-derived products are gaining ground [10]. The in vitro antibacterial
activity of coffee beans against Gram-positive and Gram-negative bacteria has also been reported. Furthermore,
different natural active chemicals in coffee of low molecular weight such as trigonelline, caffeic acid and
5-caffeoylquinic acid have shown activity against the growth of Legionella pneumophila, Enterobacteria and S. mutans
[11,12].
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In view of these findings, the present study was undertaken to further assess the potential applications as a way of
adding value to SCG extracts from Arabica and Robusta species by the recovery of total phenolics, flavonoids,
carotenoids and caffeine quantification. Additionally, this study aimed to investigating the antibacterial efficacy and
antifungal activity of crude aqueous of SCG to promote the use of this coffee by-product as a natural and an
inexpensive food supplements or pharmaceutical additive.
2. Chemical characterization, in vitro antioxidant activity and antibacterial and
antifungal activities of spent coffee grounds
2.1 Phytochemicals composition
Fine grinded spent coffee grounds Veracruz® constituted by 80 % Arabica and 20 % Robusta coffee beans (Coffea
canephora var. robusta and Coffea arabica, respectively), 100 % Guatemala Los Volcanes Arabica Sanzala® and 100
% Uganda SCR18 Robusta Sanzala® were obtained by an Elen® express machine ma/ c/ 3 gr, gently provided by a
local commercial source (Café Vera Cruz). Spent coffee grounds were sterilized in an autoclave JSM 250 at 134 °C
during 40 min, until 5 % moisture content and stored in airtight bottles for further analysis. For the analysis of total
phenolics and flavonoids, a simple aqueous extraction was conducted according to Costa et al. [1]. Briefly, 5 g of
ground sample and 50 mL of 100 % water was mixture (600 rpm) at room temperature for 60 min. The final extracts
were filtered and stored at -25 ºC to prior analysis. Total phenolics contents (TPC) of spent coffee grounds extracts were
determined spectrophotometrically according to a modified method of Costa et al. [1]. Briefly, 500 μL of each extract
were mixed with 2.5 mL of the Folin-Ciocalteu reagent (1:10) and 2 mL of a sodium carbonate solution (7.5 %). After 1
h incubation the absorbance was measured at 765 nm and results were expressed as mg of gallic acid equivalents
(GAE)/ g of sample.
Total flavonoids contents were determined according to Barroso et al. [13]. Aliquots of 1 mL of each extract were
mixed with 4 mL of distilled water and 300 μL of 25% sodium nitrite. After 5 min, 300 μL of 10% AlCl3 were added
and 1 min after 2 mL of sodium hydroxide (1 M) and 2.4 mL of ultrapure water. The absorbance was recorded at 510
nm and final results were expressed as mg catechin equivalents (CE)/ g of sample.
Chlorophyll a, chlorophyll b, β-carotene and lycopene were determined, in triplicate, according to Vinha et al. [14].
Briefly, samples were extracted with acetone/hexane (2:3, v/v), and supernatants absorbance were measured at 453,
505, 645, and 663 nm. The contents of chlorophyll a, chlorophyll b, β-carotene and lycopene were calculated according
to the following equations: Chlorophyll a (mg/ g) = 0.999A663 – 0.0989A645; Clorophyll b (mg/ g) = -0.328A663 +
1.77A645; Lycopene (mg/ g) = -0.0458A663 + 0.204A645 + 0.372A505 – 0.0806A453; -Carotene (mg/ g) = 0.216A663
1.22A645 – 0.304A505 + 0.0452A453.
For caffeine extraction coffee spent grounds (5 g) were stirred with ebullition water (150 mL) for 30 minutes. The
resulting mixture was filtered and extracted with chloroform: isopropanol (3:1, w/w) (4 x 50 mL). The organic extract
was dried with CaCl2, filtered and evaporated to dryness [15]. The same procedure was used for caffeine determination
in commercial 80 % Arabica and 20 % Robusta Veracruz® fresh grounds. The resulting extracts were quantitatively
dissolved in ultra-pure H2O and caffeine was quantified by HPLC with an UV detector (214 nm), using benzoic acid as
internal standard in the same concentration as the standards [16]. Standard solutions of 20, 40, 60, 80, 100, 120 and 160
mg/ L in caffeine and 100 mg/ L in benzoic acid in ultra-pure H2O were prepared. An aliquot (50 L) of each sample
was injected and its concentration was determined using linear regression analysis. Standards and samples were
measured in triplicate and the mean peak height values were used for data acquisition. Identification of caffeine and
benzoic acid was performed by comparison with retention time of the respective standards. Areas under the curve were
calculated and calibration curves were obtained by plotting area caffeine / area benzoic acid versus caffeine
concentration.
2.1.1 Antioxidant activity
The free radical scavenging activity of the samples was measured in vitro by 2,2 - diphenyl-1-picrylhydrazyl (DPPH)
assay according to the same author described earlier [14]. Briefly, 14 μL of diluted extract of each sample (1:10) were
mixed with 186 μL of a freshly prepared DPPH solution (9.3×105 mol/ L in ethanol). The decrease of the DPPHwas
measured in equal time intervals of 10 min by monitoring the decrease of absorption at 525 min, in order to observe the
kinetics reaction. The reaction endpoint was attained in 40 min. A calibration curve was prepared with trolox (10–2000
μg/ L, r = 0.9995) and DPPH scavenging activity was expressed as mg of trolox equivalents (TE)/ g of sample.
2.2 Antibacterial and antifungal activities of spent coffee grounds
SCG antimicrobial activity was tested against Gram positive (S. aureus) and Gram negative (E.coli and P. aeruginosa)
bacteria and yeasts (Candida sp.) since treatment of infectious diseases is, from ever, a challenge to the science. Besides
the number and diversity of antimicrobial drugs available, microorganisms were throughout the times capable of
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developing resistance mechanisms to the therapeutic options as Methicillin-resistant Staphylococcus aureus (MRSA),
Vancomycin intermediate Staphylococcus (VISA), Vancomycin-resistant Staphylococcus aureus (VRSA) or extended-
spectrum -lactamases (ESBLs) producers [17].
Antifungal resistance is also becoming a problem. Candida albicans is the major cause of candidosis, but C. krusey
(intrinsically resistant to fluconazole) and C. parapsilosis causes medically important infections, difficult to treat [18].
2.2.1 Chemicals, Reagents and Microorganisms
Mueller-Hinton II (MH II) broth and Sabouraud dextrose agar (SDA) were from Liofilchem (Italy). Microorganisms
stocks were kept at -20 ºC and cultures at 4 ºC. Bacteria (E. coli ATCC25922, P. aeruginosa ATCC27853, and S.
aureus ATCC29213) and yeasts (C. albicans ATCC 10231, C. krusei ATCC6258 and C. parapsilosis ATCC2209) were
cultured in MH II agar and SDA, respectively, 24 h just prior to the assays.
2.2.2 Antibacterial and antifungal activity assays
The lyophilized spent coffee ground extracts (commercial mixture) were solubilized in sterilized distilled water (10 mg/
mL) and stock solutions kept at -20ºC before analysis.
Minimal inhibitory concentration (MIC) of the extract was determined using the CLSI Reference Microdilution
Method for Antimicrobial Susceptibility Testing for Aerobic Bacteria M7-A6 [19]. Briefly, serial dilutions (1:2; ranging
from 1.0 to 0.25 mg/ mL) of the stock extract on MH II broth were added to the test bacteria (5 x 105 UFC/ mL) and
were incubated for 24 h at 37 ºC. Positive controls (microorganism in culture media), negative controls (culture media),
and extract control (extract in culture media) were included in all the experiments. MIC was defined as the lowest
concentration that completely inhibited bacterial growth by visual lecture.
MIC of the extract was determined using the CLSI Reference Method for Broth Dilution Antifungal Susceptibility
Testing of Yeasts M27-A3 [20]. Briefly, serial dilutions (1:2; ranging from 1.0 to 0.25 mg/ mL) of stock extract on
RPMI-1640 broth medium supplemented with MOPS were added to the test yeast (0.5-2.5 x 103 CFU/ mL) and were
incubated for 48 h at 37 ºC. Positive controls (microorganism in culture media), negative controls (culture media), and
extract control (extract in culture media) were included in all the experiments. MIC was defined as the lowest
concentration that completely inhibited yeast growth by visual lecture.
3. Results and Discussion
Spent coffee grounds of the three samples were extracted with an environmentally friendly procedure (water) and
analyzed to evaluate the recovery of relevant natural antioxidants for further possible use as nutritional supplements,
foods, cosmetic additive, or for pharmaceutical applications. The phytochemical composition of the spent coffee
grounds extracts is given in Table 1, Table 3 and Figure 2.
Table 1 Phytochemical composition and in vitro antioxidant activity of the aqueous extracts obtained from three different coffee
grounds (100 % Arabica, 100 % Robusta, and commercial mixture: 80 % Arabica + 20 % Robusta).
Spent Coffee Grounds
*
Phytochemicals Arabica Robusta Commercial mixture
Phenolics 14.97±0.09
b
22.56±1.02a 11.04±0.17c
Flavonoids 2.12±0.04
b
3.49±0.46a 1.09±0.16c
Chlorophyll a 0.0494±0.002a 0.0280±0.001c 0.0393±0.002
b
Chlorophyll b 0.0873±0.004a 0.0042±0.000c 0.0653±0.004
b
Lycopene 0.0079±0.000
b
0.0011±0.000c 0.0258±0.001a
Antioxidant activity
81.57±2.32
b
88.16±1.16a 73.7±1.44c
*a,b,cDifferent letters stand for significant differences (p < 0.01) in mean value, according to the LSD post-hoc test (ANOVA).
Table 2 Correlation [r (p-value)] of the phytochemical composition and in vitro antioxidant activity of the aqueous extracts obtained
from three different coffee grounds (100% Arabica, 100% Robusta, and commercial mixture: 80 % Arabica + 20 % Robusta).
Flavonoids Chlorophyll a Chlorophyll b Lycopene Antioxidant activity
Phenolics 0.966 (<0.001) -0.847 (0.004) -0.819 (0.007) -0.900 (0.001) 0.941 (<0.001)
Flavonoids -0.773 (0.015) -0.747 (0.021) -0.919 (<0.001) 0.927 (<0.001)
Chlorophyll a 0.998 (<0.001) 0.552 (0.123) -0.698 (0.037)
Chlorophyll b 0.511 (0.160) -0.656 (0.055)
Lycopene -0.950 (<0.001)
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Fig. 1 Relation between the concentrations of bioactive
compounds ( stands for Lycopene (multiplied by a 1000
factor);  stands for Phenolics and  stands for Flavonoids.
Black, grey and white represents SCG commercial mixture,
SCG Arabica and SCG Robusta, respectively) and antioxidant
activity. Lines were used to show the tendency observed in the
relations between compounds and their antioxidant activity.
SCG is the main by-product of the brewing process and a potential source of bioactive compounds, mainly phenolic
acids easily extracted with water. Knowledge of the total content of phenolic compounds in spent coffee extracts is
crucial for their potential use as functional ingredients by the food and pharmaceutical industries. For comparison, the
commercial spent coffee grounds presented lower contents of total phenolics and flavonoids (11.04 mg GAE/ g, 1.09
mg CE/ g, respectively) than SCG coffee grounds of 100 % Arabica and 100 % Robusta extracts. However, antioxidant
activity showed significant differences (p < 0.001) in the 3 formulations, with the commercial mixture having the lowest
and Robusta the highest antioxidant activity (Table 1). The total phenolics and flavonoids were strongly and positive
correlated with the DPPH scavenging activity (r = 0.941, p < 0.001 and r = 0.927, p < 0.001, respectively, Table 2),
suggesting that an increase in phenolic and flavonoid compounds are mainly responsible for the increase in antioxidant
activity (Figure 1).
The antioxidant potential of plant extracts and pure compounds was measured using more than one in vitro assay,
once each of these assays is based on one feature of antioxidant activity, such as antiradical ability or to inhibit lipid
peroxidation. Carotenoids are known to be very efficient physical and chemical quenchers of singlet oxygen (1O2), as
well as potent scavengers of other reactive oxygen species (ROS), however, in the present study, regarding their
antioxidant activity, a different correlation was observed, showing an inverse significant correlation, with lycopene and
chlorophyll-a increase being strongly associated with a decrease in antioxidant activity (r = -0.950, p < 0.001 and r
= -0.698, p = 0.037, respectively, Table 2).
In addition to the compounds quantified in this work, other biologically active coffee components with potential
beneficial health effects are nicotinic acid, trigonelline, quinolinic acid, tannic acid, and pyrogallic acid [5]. However,
the presence of carotenoids in SCG can also be used as substrate for biotechnological, several applications in food
industry (food colorants, antioxidants, animal feed supplements) and also in cosmetics and pharmacy. Generally, the
market demand for carotenoids is expected to increase substantially, since those compounds exhibit significant
anti-carcinogenic activities of alternative high value product. Thus, beyond the direct relationship between phenolic
compounds and their antioxidant action, antioxidant properties such as reactive oxygen species (ROS) scavenging have
also been recently proposed for caffeine, the most abundant alkaloid present in coffee beans. Caffeine content was
analyzed by HPLC-UV and Figure 2 shows an illustrative chromatogram.
Fig. 2 Illustrative chromatogram of coffee grounds
extracts. The 1
st
peak correspond to caffeine and the
2
nd
to benzoic acid (used as internal standard).
Caffeine retention time was 2.2 min, while benzoic acid takes 3.6 min to separate (Figure 2). The equation of the
regression lines obtained was y = 0.0155x + 0.1865, being y the areas quotient and x the caffeine concentration.
Naturally, the coffee grounds obtained from different varieties of coffee will contain different amounts of caffeine
(Table 3). In this study that is demonstrated in the specific case of varieties C. Robusta and C. Arabica. Caffeine content
in commercial mixture SCG was 0.82 ± 0.14 % (m/m), while in the fresh grounds was 2.43 ± 0.48 %, contain with the
0
5
10
15
20
25
30
65 70 75 80 85 90 95
Concentration of bioacti ve compounds (mg/g)
Antioxidant activity using DPPH assay (micromol Trolox/g)
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humidity values of the samples. The results reveal that in the process of producing the so called “Espresso”
approximately 30 % of the caffeine remains on the coffee spent.
Table 3 Caffeine content in % (m/m) of the several coffee grounds studied (Commercial fresh grounds, 100 % Arabica SCG, 100 %
Robusta SCG, and commercial mixture 80 % Arabica + 20 % Robusta SCG).
Caffeine content, % (m/m)
Fresh grounds 2.43±0.48
Arabica SCG 0.30±0.01
Robusta SCG 1.14±0.01
Commercial mixture SCG 0.82±0.14
Comparing with other results previously published, we have obtained quantities for SCG caffeine similar to the
referred by Cruz et al. (2012) [21], and considering that coffee commercially more used in Portuguese coffee shops has
15-20 % Robusta and 80-85 % Arabica. They have obtained 194.0 to 787.7 mg caffeine/ 100 g (0.1940 % - 0.7877 %)
on the SCG collected in bars of Oporto city, using 50 mL of distilled water to extract 5 g SCG during 5 minutes, with
stirring and at boiling temperature [21]. Bravo et al. [22] have dried spent coffee, defatted with petroleum ether (1:11,
w/v) for 3 h at 60 °C in a Soxhlet extraction system, using 24 g of SCG with 400 mL of water in a filter coffeemaker
during approximately 6 min at 90 °C and referred ranges from 0.359 % for Arabica to 0.809 % for Robusta. Panusa et
al. (2013) [5] published 6.00 ± 0.05 mg/ g (0.600 %) (water extract) and almost the same value for EtOH/H2O (60:40)
(v/v) extract (5.99 ± 0.16 mg/ g ) for 2 g of dried SGC of coffee with 70 % Arabica, with 100 mL of the solvent, at 60
ºC, during 30 min.
The caffeine quantity differences can be explained by same factors: the ratio Arabica/Robusta, the extraction time,
the ratio between the volume of the solvent and the mass of the sample, the extraction temperature and the grind of the
coffee beans.
Spent coffee ground extracts showed to inhibit some Gram-positive and Gram-negative bacterial strains (Table 4). S.
aureus and E. coli growth was inhibited for concentrations of 1.0 mg/ mL. At that concentration, no inhibition was
observed for P. aeruginosa. A stronger inhibition of coffee ground extract was observed against Candida sp.. C.
albicans, C. krusei and C. parapsilosis growth was totally inhibited for concentration of 0.5 mg/ mL.
Table 4 Antibacterial and antifungal activity (MIC, minimal inhibitory concentration) of spent coffee ground extracts.
Microorganism strain MIC (mg/ mL)
Bacteria
S. aureus ATCC29213 1.0
E. coli ATCC25922 1.0
P. aeruginosa ATCC27853 >1.0
Yeast
C. albicans ATCC10231 0.5
C. krusei ATCC6258 0.5
C. parapsilosis ATCC22019 0.5
*Results are obtained from at least 2 to 3 independent experiments performed in duplicate.
Our results suggest that spent coffee ground extracts are potentially useful in cosmetic formulations, due to their
referred properties, including antifungal and antibacterial activities. The inclusion of those extracts on soaps or
formulations to be applied in superficial infections caused by microorganisms, as in acne or superficial candidosis,
could (i) improve the results of antimicrobial therapy, (ii) solve problems of antimicrobial resistance and (iii) improve
therapeutics adhesion, being (iv) cheaper and lowering the cost/benefit of therapeutics.
4. Conclusions
The coffee industry has experienced a constant growth and, as a consequence, large amounts of residues are generated
worldwide. One of the main coffee residues are spent coffee grounds (SCG), which are the solid residues obtained after
preparation of the coffee beverages. References to its use as organic fertilizer in domestic cultures, especially in
gardens, are common. However, scientific evidence of its effectiveness or even safety remains largely unknown.
Different attempts to valorize this waste stream of coffee industry were made. Coffee is known as valuable source of
biologically active phytochemicals such phenolic compounds and caffeine. New beneficial properties of the spent
coffee grounds are being continuously discovered. The water as solvent showed to be a good option for an efficient
extraction of bioactive compounds from SCG Additionally, SCG revealed to be a good source of antioxidant
compounds, showing a direct correlation with the antioxidant activity. The caffeine content quantified in our samples
may be used in pharmaceutical applications, depending on the site of action, dosage, and timing of drug exposure.
Furthermore, SCG presented an inibitory activity against S. aureus and E. coli. A stronger inhibition was also observed
against Candida sp. growth (C. albicans, C. Krusei and C. parapsilosis). This study allows us to understand whether the
residues generated during coffee brewing procedure, produced in large amounts in cafeterias and restaurants, or at
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domestic levels, can be considered as a source of natural antioxidants. These findings open up possibilities to evaluate
SCG chemicals as bioactive compounds in different food and pharmaceutical applications.
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... Coffee is one of the most consumed beverages and traded commodities in the world and is also a major contributor to dietary antioxidant intake [12]. Coffea arabica and Coffea canephora var. ...
... Coffea arabica and Coffea canephora var. robusta are the two main species cultivated for coffee commercial production [12][13][14][15]. Besides being a rich source of antioxidants, coffee also has several bioactive metabolites such as xanthines, phenolics, melanoidins, diterpenes, flavonoids, carotenoids, vitamin precursors, and chlorogenic acids, and its consumption is associated with less risk of developing neurodegenerative diseases and less oxidative stress [12,13,16]. ...
... robusta are the two main species cultivated for coffee commercial production [12][13][14][15]. Besides being a rich source of antioxidants, coffee also has several bioactive metabolites such as xanthines, phenolics, melanoidins, diterpenes, flavonoids, carotenoids, vitamin precursors, and chlorogenic acids, and its consumption is associated with less risk of developing neurodegenerative diseases and less oxidative stress [12,13,16]. Most of these beneficial properties have been associated with coffee but is not yet clear if these benefits are equally present in caffeinated and decaffeinated coffee. ...
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Coffee is one of the most popular and consumed products in the world, generating tons of solid waste known as spent coffee grounds (SCG), containing several bioactive compounds. Here, the antifungal activity of ethanolic SCG extract from caffeinated and decaffeinated coffee capsules was evaluated against yeasts and filamentous fungi. These extracts had antifungal activity against Candida krusei, Candida parapsilosis, Trichophyton mentagrophytes, and Trichophyton rubrum, all skin fungal agents. Moreover, SCG had fungicidal activity against T. mentagrophytes and T. rubrum. To understand the underlying mechanisms of the antifungal activity, fungal cell membrane and cell wall components were quantified. SCG caused a significant reduction of the ergosterol, chitin, and β-(1,3)-glucan content of C. parapsilosis, revealing the synthesis of this membrane component and cell wall components as possible targets of these extracts. These extracts were cytotoxic for the tumoral cell lines tested but not for the non-tumoral PLP2 cell line. The analysis of the phenolic compounds of these extracts revealed the presence of caffeoylquinic acid, feruloylquinic acid, and caffeoylshikimic acid derivatives. Overall, this confirmed the antifungal activity of spent coffee grounds, presenting a potential increase in the sustainability of the life cycle of coffee grounds, as a source for the development of novel antifungal formulations, especially for skin or mucosal fungal infections.
... Biji dan kulit biji kopi telah diketahui memiliki berbagai macam aktivitas biologis yang bermanfaat bagi kesehatan (Esquivel & Jiménez, 2012). Biji kopi aktif sebagai anti jamur (Nonthakaew et al., 2015) dan antibakteri (Sousa et al., 2015). Bahkan limbah dari pengolahan kopi juga dapat dimanfaatkan sebagai bahan alami untuk antibakteri dan anti jamur (Sousa et al., 2015). ...
... Biji kopi aktif sebagai anti jamur (Nonthakaew et al., 2015) dan antibakteri (Sousa et al., 2015). Bahkan limbah dari pengolahan kopi juga dapat dimanfaatkan sebagai bahan alami untuk antibakteri dan anti jamur (Sousa et al., 2015). Walaupun demikian, kopi dan by-product kopi belum dimanfaatkan secara optimal sesuai dengan potensinya sebagai bahan maupun produk kesehatan kulit. ...
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Kegiatan pengabdian pada masyarakat (PPM) bertujuan untuk: (1) meningkatkan pengetahuan masyarakat Seyegan tentang bahan dan manfaat sabun scrub alami dari ampas kopi, (2) meningkatkan ketrampilan masyarakat dalam pemanfaatan teknologi tepat guna pembuatan sabun scrub alami dari ampas kopi, dan (3) memotivasi minat wirausaha masyarakat Seyegan. Kegiatan PPM ini bersifat pelatihan dan dilaksanakan dengan metode ceramah, diskusi dan praktik. Melalui kegiatan tersebut, peserta telah mendapat materi tentang: (1) pembuatan sabun scrub alami dari ampas kopi, (2) kandungan dan manfaat kopi untuk kesehatan kulit, (3) sabun yang aman untuk kesehatan kulit, (4) peluang wirausaha sabun kopi, dan (5) pewarna dan pewangi yang bersifat skin grade. Peserta yang telah mengikuti pelatihan ini berjumlah 11 orang yang merupakan masyarakat di daerah Padukuhan Kamal Wetan, Mangsel VII, Margomulyo, Seyegan. Evaluasi kegiatan PPM dilakukan dalam 2 tahapan, yaitu evaluasi proses melalui observasi selama kegiatan PPM dan evaluasi hasil melalui produk sabun yang dihasilkan serta isian angket kegiatan PPM. Melalui kegiatan ini, dapat disimpulkan bahwa peserta pelatihan telah memperoleh (1) manfaat tentang bahan dan sabun alami dari ampas kopi, (2) pengetahuan dan keterampilan dalam pemanfaatan teknologi tepat guna pembuatan sabun scrub alami dari ampas kopi, namun motivasi dan minat wirausaha peserta pelatihan untuk membuat sabun scrub ampas kopi masih perlu untuk ditingkatkan.
... The enhancement in survival rates could be attributed to the improvement of immune parameters. Coffee by-products, including CSS, have been reported to contain antibacterial, antifungal, antioxidant, and anti-infectious components (including phenolic compounds, melanoidins, diterpenes, xanthines, and carotenoids) which are associated with therapeutic and pharmaceutical effects [171,172]. ...
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Biofloc technology (BFT) is a relatively new microbial-based cultivation system that can be adopted to accomplish more sustainable aquaculture and circularity goals. This review explores aspects of BFT integrating the utilization of probiotics and phytobiotics as dietary and water supplements. This scientific-based snapshot unpacks some physiological pathways and brings a literature review on how these supplements can boost water quality, as well as aquatic species’ growth, health, and survival. Probiotics, live microorganisms that confer health benefits on the host when administered in adequate dosage, are noted for their ability to bolster animal defenses and sustain water quality in farming conditions. Recent studies showcased that selected bacteria, yeast, and fungi, once added into biofloc-based systems can enhance animal performance, act as a tool for water quality management and protect fish and crustaceans against diseases. On the other hand, phytobiotics are additives sourced from plants that normally are added into compounded feeds and are known for their health and growth benefits in aquatic animals. These additives contain plant-based substances/extracts that play a key role to suppress inflammation, pathogens, and can also act as antioxidants. These selected ingredients can promote healthy gut microbiota, improve feed efficiency, and turn on genes responsible for immunity improving disease resistance of fish/shrimp. According to this review, the adoption of probiotics and phytobiotics in BFT can greatly increase farm outputs by producing healthier animals, as well as promoting growth and consistent yields. Lastly, this review showcases the importance of proper section of probiotics and phytobiotics in order to achieve a functioning BFT. Despite its numerous advantages, BFT faces several challenges, especially related to microbial management. Probiotics and phytobiotics are practical tools that can play a crucial role to obtain a more stable environment with a desirable microbial population in water and gut. Future directions in the field should focus on optimizing the utilization of these supplements for a more resilient and sustainable BFT aquaculture.
... During the coffee grain production and preparation process, several by-products are generated, including skin, pulp, parchment layer, silver membrane and SCG, which makes up the bulk of the coffee waste. SCG could be defined as the fixed residual fraction obtained after coffee preparation (Sousa et al., 2015). SCG composition is quite variable and depends on many factors, for example, the type of coffee, growing conditions, as well as the method of coffee preparation. ...
Article
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Currently, coffee is among the most consumed non-alcoholic beverages in the world. Due to the increased consumer demand for coffee, there is an excessive production of waste arising during this beverage preparation. The accumulated waste from coffee consumption is in literature named spent coffee grounds (SCG). The accumulation of SCG can adversely affect the environment. When significant amounts of SCG are disposed of inlandfills, their anaerobic degradation occurs, which leads to the formation and emissions of greenhouse gases such as methane and carbon dioxide. Furthermore, chemical substances are released into the environment, such as tannins, polyphenols or caffeine, which can affect soil fertility. In order to reduce the undesirable impact on the environment, various repeated methods of this by-product utilization and their application on the market are being studied. The aim of the work was to create an up-to-date overview of the use of SCG invarious branches of industry. The information obtained can be considered usable foundation and base for further research about SCG.
... The composition of phenolic compounds in SCGs may vary due to the methods of brewing coffee which influence the overall SCGs' composition. Caffeine and chlorogenic acid are the most extensively studied phenolic components in SCGs due to their antioxidant properties [36]. These phenolic compounds have antioxidant and metal-chelating properties, which can protect against free radical damage and reduce the risk of degenerative diseases [37]. ...
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With growing concern over environmental sustainability and dwindling fossil resources, it is crucial to prioritise the development of alternative feedstocks to replace fossil resources. Spent coffee grounds (SCGs) are an environmental burden with an estimated six million tons being generated on a wet basis annually, globally. SCGs are rich in cellulose, lignin, protein, lipids, polyphenols and other bioactive compounds which are important raw materials for use in industries including pharmaceuticals and cosmetics. Furthermore, the energy sector has the potential to capitalize on the high calorific value of SCGs for biofuel and biogas production, offering a sustainable alternative to fossil fuels. SCGs are readily available, abundant, and cheap, however, SCGs are currently underutilized, and a significant amount are dumped into landfills. This review explores the potential of SCGs as a source of a value-added compound through various conversion technologies employed in the valorisation of SCGs into biochar, biofuel, and important chemical building blocks. The state-of-the-art, current knowledge, future research to stimulate the creation of sustainable products, and the challenges and economic feasibility of exploring SCGs in a biorefinery context are presented.
... The recovery of bioactive compounds from SCG with great antioxidant properties has been reported (Bravo et al., 2012), whereas the target in this study was hydrophilic bioactive compounds. Other studies have also demonstrated that SCG polar and non-polar compounds present desirable bioactivities such as antibacterial, antifungal, anti-cancer, anti-inflammatory and anti-hypertensive activities (Rufián-Henares & Morales, 2007;Silva et al., 2015;Garcıá-Gutiérrez et al., 2017). ...
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This study investigated the effect of sequential extraction techniques and pretreatment methods in enhancing the recovery of high‐value products from spent coffee ground. Supercritical carbon dioxide (SC‐CO2) deoiling was performed to recover non‐polar lipids, and subcritical water (SCW) hydrolysis of deoiled spent coffee ground (SCG) was conducted involving pretreatment with ultrasound (US‐SCG), and sample particle size reduction (PS‐SCG). SCW temperature, solid/liquid mixing ratio, constant pressure and residence time were studied for their effect on extracting reducing sugars (RS), total phenolic content (TPC), total flavonoid content (TFC), 5‐HMF, and furfural. Temperature increase enhanced hydrolysis efficiency and promoted RS dehydration into 5‐HMF and furfural. At 180 °C and 40 mg/600 mL, TPC, TFC and RS values increased significantly with ultrasound pretreatment correlating with improved antioxidant activities by DPPH and ABTS assays. Highest amount of 5‐HMF and furfural was obtained at 210°C (highest temperature studied) with 44.71 and 2.36 mg/100 g. Chlorogenic acid recovery was the highest in the non‐deoiled SCG (15.07 mg/100 g), with no significant difference observed in PS‐SCG, suggesting an increase due to its reduced particle size. The results of this study provide comprehensive knowledge on the combined effects of integrated engineering systems to boost the valorisation of SCGs into high‐value products.
... Other solid coffee waste such as spent coffee grounds became focus of interest by Silva et al. 2015. Spend coffee grounds showed antimicrobial activity by showed minimal inhibitory concentration of one milligram per millilitre on Staphylococcus aureus and Escherichia coli growth . ...
Chapter
The food industry is generating huge amounts of by-products, about 1,890,000 tons, which should be better recycled into pharmaceuticals, cosmetics and functional foods, for instance, in order to save costs and avoid pollution. Here we review food by-products and methods of extraction. We present bioactive compounds from fruits, vegetable, tea, coffee, egg, nuts, meat and dairy products. Extracting methods include soxhlet, maceration, microwave, ultrasound, pressure.KeywordsFood by-productsBioactive moleculesNovel techniquesConventional techniquesGreen techniquesEnvironmental pollution
... Apart from fuel applications of SCG such as biodiesel, bioethanol and biogas other interesting avenues for SCG valorization include biopolymer, biocomposite fabrication, carotenoid, and bioactive compound extraction. Numerous comprehensive reviews and research articles pertinent to biorefinery, valorization and cascade utilization of SCG for food and non-food applications (Fig. 4) has been reported in literature (Vardon et al., 2013;Sousa et al., 2015;Georgieva et al., 2018;Peshev et al., 2018;McNutt and He, 2019;Atabani et al., 2019). Within the purview of the biorefinery framework defatted SCG was pressed (Atelier Luma, Tarbes, France) to obtain a board-type material which when optimized can be used as a packaging alternative. ...
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This study attempts to shed light on the efficacy of the solvent 2-methyloxolane (2-MeOx) as an alternative for hexane in defatting spent coffee grounds (SCG). Higher lipid yields were obtained with the bio-based solvent dry 2-MeOx (13.67%) and water-saturated 2-MeOx (15.84%) compared to hexane oil yield, which is of petroleum origin and is a known neurotoxin. Palmitic acid and linoleic acid were the principal fatty acids identified. The fatty acid profile of coffee oils obtained with hexane, dry 2-MeOx and aqueous 2-MeOx were similar. Lipid hydrolysis was observed in oils extracted with 2-MeOx, which warrants further investigation. The residual caffeine content in the defatted SCG was highest when hexane was used highlighting better solubility of methylxanthine compounds in the solvent 2-MeOx.
... SCG extracts could inhibit Aeromonas hydrophila in carp [80]. SCG contains a wide range of biological active substances with antimicrobial and antifungal activities [81]. In addition, biological substances in coffee by-products, including chlorogenic acid and caffeine are known to inhibit Staphylococcus aureus, S. epidermidis, Pseudomonas aeruginosa, Escherichia coli, Listeria monocytogenes, and yeast (Candida albicans) [82,83]. ...
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The study was executed to find out the potential effects spent coffee ground (SCG) on Nile tilapia’s skin mucosal and serum immunities, disease prevention, and growth rate reared in a biofloc system. Nile tilapia fingerlings (average weight 15.25 ± 0.07 g) were disseminated into 15 aquaria (150 liters tank-1) at a density of 20 fish per aquarium and treated five diets: SCG1 (control), SCG2 (10 g kg-1), SCG3 (20 g kg-1), SCG4 (40 g kg-1), and SCG5 (80 g kg-1) for eight weeks. A Completely Randomized Design (CRD) with three replications was applied. Growth rate, skin mucus, and serum immunities were quantified every 4 weeks; whereas the challenge study was conducted at the termination of the feeding trial. The outputs indicated that dietary incorporation of SCG give rise to the enhancement of SGR and FCR in comparison with the control, with best levels noted in fish fed SCG2 diet. Similarly, significant enhancements in skin mucosal and serum immunities were revealed in fish treated SCG2 over the control and other SCG diets. Likewise, higher survival rates against Streptococcus agalactiae were displayed in fish fed SCG, with the maximum level displayed in the fish treated SCG2. In conclusion, dietary supplementation of SCG2 (10 g kg-1) can be potential used as immunostimulants in tilapia aquaculture.
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Volatile fatty acids (VFAs) are the important intermediates indicating the stability and performance of fermentation process. This study developed the spectrophotometric method for determining high-range VFA concentration in mixed-acid fermentation samples. The performance was compared with the gas chromatography (GC) technique. The calibration curves of the modified method showed linearity over a wide and high concentration range of 250–5000 mg/L for individual C2–C6 VFAs in both linear and branched chains. In order to evaluate the modified method for VFA determination in complex fermentation matrices, fermentation samples produced from acidogenic fermentation of plant materials were spiked with acetic (500–1500 mg/L) and butyric acids (1000 mg/L). The accuracy and precision of the modified method for VFA determination were in the range of 94.68–106.50% and 2.35–9.26%, respectively, comparable to the GC method (94.42–99.13% and 0.17–1.93%). The developed method was applicable to measuring all C2–C6 compounds and VFA concentrations in the fermentation samples and had an acceptable accuracy and precision. The proposed method is analytically reliable and offers significant advantages in the rapid determination of VFAs in mixed acid fermentation of organic residues.
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Ilex paraguariensis A. St. -Hil. is a native species of southern South America. The caffeine content in Ilex paraguariensis leaves has been considered an important quality parameter for maté-derived products. In this work different extraction methods for the determination of these methylxantines are compared. The influence of the extraction conditions on the methylxanthine yields was evaluated. Extraction by decoction with acidic aqueous solution (H2SO4 4N) presented the higher efficiency in the theobromine extraction. The extraction in a Soxhlet with acidic aqueous solution and decoction with acidic aqueous solution showed the highest caffeine yield. For the concomitant theobromine and caffeine quantification, the decoction with acidic aqueous solution is suggested.
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Coffee is one of the most consumed beverages in the world and is the second largest traded commodity after petroleum. Due to the great demand of this product, large amounts of residues are generated in the coffee industry, which are toxic and represent serious environmental problems. Coffee silverskin and spent coffee grounds are the main coffee industry residues, obtained during the beans roasting, and the process to prepare “instant coffee”, respectively. Recently, some attempts have been made to use these residues for energy or value-added compounds production, as strategies to reduce their toxicity levels, while adding value to them. The present article provides an overview regarding coffee and its main industrial residues. In a first part, the composition of beans and their processing, as well as data about the coffee world production and exportation, are presented. In the sequence, the characteristics, chemical composition, and application of the main coffee industry residues are reviewed. Based on these data, it was concluded that coffee may be considered as one of the most valuable primary products in world trade, crucial to the economies and politics of many developing countries since its cultivation, processing, trading, transportation, and marketing provide employment for millions of people. As a consequence of this big market, the reuse of the main coffee industry residues is of large importance from environmental and economical viewpoints. KeywordsCoffee–Silverskin–Spent grounds–Cellulose–Hemicellulose
Article
Coffee melanoidins have attracted interest as a result of its potential health benefits. This investigation aims to elucidate the extraction behavior of melanoidins and their populations during the preparation of portioned espresso coffee and its relationship with the antioxidant activity of the coffee brew. Filter-paper pods, FAP capsule, and clone capsule containing light roasted coffee have been investigated. An accumulative fractionation approach has applied to model the extraction kinetics of melanoidins, melanoidin populations, browning, chlorogenic acids (CGA), and antioxidant activity. Melanoidins were very efficiently extracted in clone capsules since less than 9 s was necessary to extract the 50% of the melanoidin content as compared with pods and FAP capsules, and the kinetic of extraction is slower than CGA. The extraction profile of melanoidins and browning fitted better with the antioxidant capacity than CGA and total solids profile. Melanoidin populations were obtained according to ethanol solubility. Total melanoidin content and the ratio between melanoidin populations did not change during extraction volume for espresso coffee. Melanoidin populations soluble at 75% ethanol showed the highest antioxidant activity. However, melanoidins with higher antioxidant activity are extracted at higher volumes. This investigation could make possible the adjustment of the technological requirements of espresso coffeemakers to produce an espresso coffee with high levels of beneficial compounds.
Article
Abstract The effect of pre-meal tomato intake in the anthropometric indices and blood levels of triglycerides, cholesterol, glucose, and uric acid of a young women population (n = 35, 19.6 ± 1.3 years) was evaluated. During 4 weeks, daily, participants ingested a raw ripe tomato (∼90 g) before lunch. Their anthropometric and biochemical parameters were measured repeatedly during the follow-up time. At the end of the 4 weeks, significant reductions were observed on body weight (-1.09 ± 0.12 kg on average), % fat (-1.54 ± 0.52%), fasting blood glucose (-5.29 ± 0.80 mg/dl), triglycerides (-8.31 ± 1.34 mg/dl), cholesterol (-10.17 ± 1.21 mg/dl), and uric acid (-0.16 ± 0.04 mg/dl) of the participants. The tomato pre-meal ingestion seemed to interfere positively in body weight, fat percentage, and blood levels of glucose, triglycerides, cholesterol, and uric acid of the young adult women that participated in this study.
Article
Spent coffee-grounds (SCG) were extracted with an environmental friendly procedure and analyzed to evaluate the recovery of relevant natural antioxidants for use as nutritional supplements, food or cosmetic additives. SCG were characterized in terms of their total phenolic content by the Folin-Ciocalteu's procedure and antioxidant activity by the DPPH scavenging assay. Flavonoids content was also determined by a colorimetric assay. The total phenolic content was strongly correlated with the DPPH scavenging activity, suggesting that phenolic compounds are the main responsible for the antioxidant activity of SCG. An UHPLC-PDA-TOF-MS system was used to separate, identify and quantify phenolic and non-phenolic compounds in the SCG extracts. Important amounts of chlorogenic acids (CGA) and related compounds as well as caffeine (CAF) evidenced the high potential of SCG, a waste material that is widely available in the world, as a source of natural phenolic antioxidants.
Article
The main hydrophilic antioxidant compounds (3-, 4- and 5-monocaffeoylquinic and 3,4-, 3,5- and 4,5-dicaffeoylquinic acids, caffeine and browned compounds, including melanoidins) and the antioxidant capacity (Folin-Ciocalteau, ABTS, DPPH, Fremy´s salt and TEMPO) were evaluated in Arabica and Robusta spent coffee obtained from the preparation of coffee brews with the most common coffeemakers (filter, espresso, plunger and mocha). All spent coffee grounds, with the exception of those from mocha coffeemaker, had relevant amounts of total caffeoylquinic acids (6.22-13.24 mg/g of spent coffee), mainly dicaffeoyquinic acids (3.31-5.79 mg/g of spent coffee) which were 4-7 fold higher than in their respective coffee brews. Caffeine was ranged from 3.59 to 8.09 mg/g of spent coffee. The antioxidant capacity of the aqueous spent coffee extracts was 46.0-102.3% (filter), 59.2-85.6% (espresso), and less than 42% (plunger) in comparison to their respective coffee brews. This study allowed us to obtain spent coffee extracts with antioxidant properties that can be used as a good source of hydrophilic bioactive compounds.
Article
Espresso spent coffee grounds were chemically characterized to predict their potential, as a source of bioactive compounds, by comparison with the ones from the soluble coffee industry. Sampling included a total of 50 samples from 14 trademarks, collected in several coffee shops and prepared with distinct coffee machines. A high compositional variability was verified, particularly with regard to such water-soluble components as caffeine, total chlorogenic acids (CGA), and minerals, supported by strong positive correlations with total soluble solids retained. This is a direct consequence of the reduced extraction efficiency during espresso coffee preparation, leaving a significant pool of bioactivity retained in the extracted grounds. Besides the lipid (12.5%) and nitrogen (2.3%) contents, similar to those of industrial coffee residues, the CGA content (478.9 mg/100 g), for its antioxidant capacity, and its caffeine content (452.6 mg/100 g), due to its extensive use in the food and pharmaceutical industries, justify the selective assembly of this residue for subsequent use.
Article
The antioxidant profiles of 39 water samples (29 flavored waters based on 10 natural waters) and 6 flavors used in their formulation (furnished by producers) were determined. Total phenol and flavonoid contents, reducing power, and DPPH radical scavenging activity were the optical techniques implemented and included in the referred profile. Flavor extracts were analyzed by HS-SPME/GC-MS to obtain the qualitative and quantitative profiles of the volatile fraction of essential oils. Results pointed out a higher reducing power (0.14-11.8 mg of gallic acid/L) and radical scavenging activity (0.29-211.5 mg Trolox/L) of flavored waters compared with the corresponding natural ones, an interesting fact concerning human health. Bioactive compounds, such as polyphenols, were present in all samples (0.5-359 mg of gallic acid/L), whereas flavonoids were not present either in flavored waters or in flavors. The major components of flavor extracts were monoterpenes, such as citral, α-limonene, carveol, and α-terpineol.
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All humans are colonized with Candida species, mostly Candida albicans, yet some develop diseases due to Candida, among which genitourinary manifestations are extremely common. The forms of genitourinary candidiasis are distinct from each other and affect different populations. While vulvovaginal candidiasis affects mostly healthy women, candiduria occurs typically in elderly, hospitalized, or immunocompromised patients and in neonates. Despite its high incidence and clinical relevance, genitourinary candidiasis is understudied, and therefore, important questions about pathogenesis and treatment guidelines remain to be resolved. In this review, we summarize the current knowledge about genitourinary candidiasis.