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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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... Phytochemicals of coffee and its byproducts represent a great source of bioactive compounds showing antioxidant activity (Duangjai et al., 2016;Pushpa S.;Murthy & Naidu, 2012a;Yashin, Yashin, Wang, & Nemzer, 2013), antimicrobial activity (Castaldo et al., 2018;Jiménez-Zamora et al., 2015;Mirón-Mérida, Yáñez-Fernández, Montañez-Barragán, & Barragán Huerta, 2019;Monente, Bravo, et al., 2015;Nishina et al., 1994;Sousa, Gabriel, Cerqueira, Manso, & Vinha, 2015) and anti-proliferative activity (Balzano et al., 2020). A study of presented polyphenol compound profiles and correlated role of the phenolic extracts from coffee husk and silverskin in fighting obesity and inflammatory disorders. ...
... To this end, reports exist indicating potential inclusion of coffee byproducts as source of antimicrobial agent in food having inhibition capacity against food pathogens (Monente, Bravo, et al., 2015). Studies exist in body of the literatures that polyphenol extracts exhibit antibacterial (Chalalai et al., 2015;Duangjai et al., 2016;Gyawali & Ibrahim, 2014;Klangpetch, 2017;Lou et al., 2011) and antifungal properties against microorganisms of related sources (Castaldo et al., 2018;Sousa et al., 2015). ...
Article
Research interests in coffee byproducts showed increased attraction. This is partly driven by the increasing annual coffee production, which leads to increased generation of solid residues creating environmental concern. Additionally, compositional profile of coffee byproducts stimulate more investigations into their role of affecting human physiological function. Driven by increased demand of valorizing agro-industrial residues into value added products, many research findings present justifiable importance and possible application of coffee byproducts in food. This extensive review therefore presents up-to-date information with reference to compositional data, potential of incorporating coffee byproducts as ingredients in food formulations and new product development with respect to their biological functionality and technological importance. Reviewed byproducts are coffee husk, pulp, parchment, silverskin and spent coffee ground. Processing steps are elaborated and description of each process with respect to characteristics of starting material and generated main products and resulting residues is made to clearly distinguish the corresponding byproducts. Respective nutritional and phytochemical composition, food formulation and their distinctive characteristics are described. Production of value added products and food product development as well as applications made so far to incorporate the byproducts into food formulation are reviewed. Finally, safety related references and prospective insights of coffee processing byproducts in the current changing economy with possible indication into future trend of the subject matter in universal context are presented.
... 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 . ...
... 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. ...
Article
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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]. ...
Article
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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.
... In comparison to experimental or commercial CFs biomass raw materials, the key advantage of the utilization of the targeted postconsumer CFs erecycled jute textile fibres and the paper cup fibrese is that the hygroscopic nature of the fibres and the nutrient availability has been originally modified by industrial processes that include delignification, antimicrobial and hydrophobic functionalization, as well as polymer coatings or linings (Mohiuddin, 2015). Similarly, spent coffee, despite of its hydrophilic nature, its phytochemical compounds, such as caffeine, exhibits antibacterial and antifungal action via direct suppression of pathogenic microbial growth and development (Sousa et al., 2015;Sugiyama et al., 2016), confirmed by the measurements performed in this study. From the manufacturing perspective the hydrothermal hotcompression examined to form the hybrid panels facilitates the materials recovery and re-processing as bulk heterogeneous fibres, avoiding the cost involved in complex sorting and performing simultaneously as supplementary sterilization treatment of the materials. ...
Article
Microbiomes in the built environment is an emerging topic of high-relevance, as biodeterioration and biodegradation of porous and polymer materials may be major public health risk factors. Epidemiological studies have confirmed indoor airborne microorganisms and their metabolites cause significant toxic immune reactions, with clinical effects associated with more than 60% of occupants' chronic infections. The present study reports the potential inhibitory effect on microbial and fungal colonization of hy-drothermal hot-compression for the manufacture of a series of novel cellulose-based panels engineered for insulating building applications. This method was examined as it is a green manufacturing technique which simultaneously self-bonds the cellulose fibres, as well as potentially having an anti-microbial effect. The technique renders the novel materials non-toxic, additive-free, biodegradation resistant, as well as increasing the recyclability potential of the materials at their end-of-life. Prototypes were formulated from three cellulosic materials sourced from complex post-consumer coffee industry heterogeneous waste stream ejute textile, paper cups, and coffee groundse holding initially high-levels of microbiological contamination. The raw materials were characterized with Infrared Spectroscopy (FTIR) and Scanning Electronic Microscopy (SEM). Microbial species were identified using culture-dependent and culture-independent DNA quantitative methods for the raw materials, as well as the processed panels. The experimental results confirmed a high-level of bacterial and fungal contamination with ubiquitous environmental bacteria such as Bacillus, Burkholderia, and Stenotrophomonas species for the Jute textile and Paper cup fibres. However, the microbes were minimized or non-detectable for all three processed panel samples. This promising result demonstrates that complex cellulosic waste materials can be converted to low-microbial biomass potential industrial feedstock for the green manufacturing of building materials.
... C. albicans, C. Krusei, and C. parapsilosis[Sousa, Gabriel, Cerqueira, Manso, & Vinha, 2015]). ...
Article
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Food by‐products happen at various stages of production and processing at home and on commercial scales. In the recent years, because of the fast‐growing food companies and production, food processing by‐products have gained a lot of interest and attracted many technical and health professionals as well as policy makers internally and internationally. Also, concerns are increasing about food by‐products due to their ecological and environmental impact on the planet. This is particularly of concern when large companies emit. Large quantities of food by‐products are thrown into environment in which they can be exploited technically, medicinally, and pharmaceutically. This is due to their chemical component and biologically active compounds of the by‐products. Therefore, this systematic review focuses on the food by‐product biological compounds present in different parts of the food products, particularly in some common foods such as fruits, vegetables, cereals, dairy products, meat, eggs, nuts, coffee, and tea. Moreover, the review also explains the kind of biologically active compounds and their quantity not just in edible foods, but also in part and types of the by‐product which then can be reused and recycled into different processes in order to extract and get benefit from.
... Several compounds have been found in coffee fruit including micronutrients (8), chlorogenic, caffeic, and ferulic acid, trigonelline, and caffeine (9,10). Coffee has been shown to possess antioxidant, antibacterial (10), antifungal (11), and antiradical activities (12). Many studies have demonstrated that coffee can prevent of Type 2 Diabetes Mellitus, improve insulin sensitivity, decreases the risk of parkinson's disease (8), reduces the risk of cancers, hepatoprotective effect and anti-inflammatory activity (13). ...
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This study was to assess the impact of different colors of coffee fruit (green, yellow and red) on adipogenesis and/or lipolysis using 3T3-L1 adipocytes. Characterization of chemical constituents in different colors of coffee fruit extracts was determined by ESI-Q-TOF-MS. The cytotoxicity of the extracts in 3T3-L1 preadipocytes were evaluated by MTT assay. Oil-red O staining and amount of glycerol released in 3T3-L1 adipocytes were measured for lipid accumulation and lipolysis activity. All coffee fruit extracts displayed similar chromatographic profiles by chlorogenic acid > caffeoylquinic acid > caffeic acid. Different colors of raw coffee fruit possessed inhibitory adipogenesis activity in 3T3-L1 adipocytes, especially CRD decreased lipid accumulation approximately 47%. Furthermore, all extracts except CYF and their major compounds (malic, quinic, and chlorogenic acid) increased glycerol release. Our data suggest that different colors of coffee fruit extract have possessed anti-adipogenic and lipolytic properties and may contribute to the anti-obesity effects. © 2018, Kobe University School of Medicine. All rights reserved.
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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.
Chapter
The invigorating effect of coffee, as well as the increased awareness of its health benefits, has resulted in its increased consumption as a beverage worldwide. Mass industrial processing of coffee beans has resulted in the accelerated generation of both solid wastes as well as wastewaters. Such agro-based organic wastes have limited applications and have severe environmental implications when disposed of indiscriminately in land and water bodies. Exploitation of the large-scale generation of coffee wastes via various technological processing methods has led to significant yields of commercially viable and environmental friendly products in the form of biofuels (biogas, biodiesel, ethanol), biofertilizers, biochemicals, biopolymers (polyhydroxyalkanoates), enzymes, polyphenols, pigments, and other by-products in the form of activated carbons. With the aim of enhancing the sustainability and growth of the coffee industry as well as curbing pollution arising from coffee processing wastes, this chapter provides in-depth knowledge of the various technological interventions, and associated parameters through which such wastes have been processed and applied for the development of various bio-based products. An up-do-date literature review has been presented on the research carried out on the green processes undertaken with various coffee wastes. Also, research gaps and expected scientific work have been highlighted with the aim of disclosing the hurdles in the pathway of the biorefinery process and sustainability/productivity of the coffee industry.
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Coffee contains active compounds that alleged to have antifungal activity. This study aimed to analyze inhibitory effect of steeping freeze–dried Robusta ground coffee (SFDRGC) to the growth of oral microorganism Candida albicans (the main causative agent of oro-pharyngeal opportunistic infection). This is an in vitro experimental study using the post–test only control group design. Serial dilutions of SFDRGC were studied. An antifungal drug Nystatin was used as a positive control, and sterile distilled water as a negative control. The inhibitory effect was study by means of Agar well diffusion method. Result showed that SFDRGC demonstrated antifungal activity. The higher concentration of SFDRGC showed the higher antifungal activities significantly (P < 0.05). Concentration of 100% SFDRGC showed anti-candida activity as potent as Nystatin. In conclusion, 100% SFDRGC demonstrated a potent antifungal agent against C. albicans. This study suggested that coffee beverage might be used as anti-candida mouthwash to prevent the risk of oral opportunistic infection. Further studies, however are needed to confirm this notion, such as epidemiological, and phytochemical studies of antifungal bioactive components in coffee that are processed using various methods.
Article
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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.
Article
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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.
Article
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.