Search

Orange and coffee grounds by-products, rich in phenolic bioactive compounds, can be used in the food industry as antioxidants, colorants, flavorings and additives, mainly because they are solvents that are easy to prepare, have a lower cost, are thermally stable, biodegradable, renewable, and are considered GRAS (Generally Recognized as Safe). Deep eutectic solvents, which are sustainable and have lower melting points, are effective for extracting these compounds. This study aimed to evaluate the use of deep eutectic solvents (DES) in extracting Total Phenolic Compounds (TPC), from orange by-products and spent coffee grounds. DES formed by citric acid: mannitol (CM-DES), and lactic acid: glucose (LG-DES), were evaluated by varying the following parameters: water content (10–50%), solid–liquid ratio (1:5–1:50 w/w) and temperature (40–50 °C). DES citric acid: mannitol presented the best efficiency in the extraction of TPC under the conditions of 10% water, 80 °C, and solid–liquid ratio 1:10 (w/w) for the orange by-products (1782.92 ± 4.50 mg GAE/L) and 1:15 (w/w) for spent coffee grounds (1620.71 ± 3.72 mg GAE/L). The highest antioxidant activity was observed in the extraction with CM-DES for both by-products in the three methods evaluated: Ferric Reducing Antioxidant Power (FRAP) (1.087 ± 0.004 and 1.071 ± 0.006 mol ascorbic acid/L), DPPH radical scavenging activity (2,2-difenil-1-picrilhidrazil—DPPH) (0.233 ± 0.003 and 0.234 ± 0.001 mol Trolox equivalent/L), and radical cation scavenging activity ABTS (2,2-azino-bis (3-ethyl-benzothiazoline-6-sulfonic acid—ABTS) (0.284 ± 7.16 and 0.319 ± 0.002 mol Trolox equivalent/L). Therefore, DES with citric acid: mannitol is a promising alternative to conventional solvents to recover phenolic compounds in agro-industrial by-products, such as orange by-products and SCG. [ABSTRACT FROM AUTHOR]

In order to reduce global warming, new energy fuels that use waste biomass to replace traditional coal are rapidly developing. The main purpose of this study is to investigate the feasibility behavior of different biomass materials such as spent coffee grounds (SCGs) and spent tea grounds (STGs) as fuel during combustion and their impact on the environment. This study involves using fuel shaping and co-firing methods to increase the fuel calorific value and reduce the emissions of pollutants, such as NOX and SO2, and greenhouse gas CO2. The produced gas content was analyzed using the HORIBA (PG-250) laboratory combustion apparatus. The results indicate that, among the measured formed particles, SCG:STG = 8:2, 6:4, and 4:6 had the lowest post-combustion pollutant gas emissions. Compared to using only waste coffee grounds as fuel, the NOx emissions were reduced from 166 ppm to 102 ppm, the CO emissions were reduced from 22 ppm to 12 ppm, and the CO2 emissions were reduced from 629 ppm to 323 ppm. In addition, the emission of SO2, the main component of acid rain, was reduced by 20 times compared to the combustion of traditional fuels. The SO2 emission of five different proportions of biomass fuels was 5 ppm, which is much lower than that of traditional coal fuels. Therefore, SCG and STG mixed fuels can replace coal as fuel while reducing harmful gasses. [ABSTRACT FROM AUTHOR]

Due to its nitrogen, phosphorus, and magnesium content, sewage sludge is used, among other things, to grow plants for energy purposes or to intensify biogas production. These processes are always accompanied by odor emissions, which are treated as pollution according to European legislation and are subject to legal regulations in many countries. Therefore, this publication presents the results of a study on the removal of odor from sewage sludge by adsorption on biochars produced from selected biowaste. Beekeeping waste (grain) and coffee brewing residues (spent coffee grounds) were selected for the study. Both materials were pyrolyzed to produce biochar which was applied for adsorption of odors from sewage sludge. Commercial Organosorb 200-1 Wi activated carbon was used as a comparison material. The odors were taken from dried sewage sludge from a municipal wastewater treatment plant. The obtained biochars are suitable for odor adsorption and can be an alternative to commercial adsorbents. The biochar from beekeeping waste showed the highest efficiency, allowing 100% odor removal. Slightly worse results were obtained for biochar from spent coffee grounds. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO2) capture has been identified as a potential technology for reducing the anthropic emissions of greenhouse gases, particularly in post-combustion processes. The development of adsorbents for carbon capture and storage is expanding at a rapid rate. This article presents a novel sustainable synthesis method for the production of chitosan/activated carbon CO2 adsorbents. Chitosan is a biopolymer that is naturally abundant and contains amino groups (–NH2), which are required for the selective adsorption of CO2. Spent coffee grounds have been considered as a potential feedstock for the synthesis of activated coffee grounds through carbonization and chemical activation. The chitosan/activated coffee ground composite microspheres were created using the emulsion cross-linking method with epichlorohydrin. The effects of the amount of chitosan (15, 20, and 25 g), activated coffee ground (10, 20, 30, and 40%w/w), and epichlorohydrin (2, 3, 4, 5, 6, 7 and 8 g) were examined. The CO2 capture potential of the composite beads is superior to that of the neat biopolymer beads. The CO2 adsorbed of synthesized materials at a standard temperature and pressure is improved by increasing the quantity of activated coffee ground and epichlorohydrin. These findings suggest that the novel composite bead has the potential to be applied in CO2 separation applications. [ABSTRACT FROM AUTHOR]

Coffee beans, a popular commodity in the world, are processed into coffee, which generates a considerable quantity of spent coffee grounds (SCGs). However, SCGs, a byproduct rich in hemicellulose, poses a challenge due to fermentable sugar loss during conventional pretreatment. This study investigates the efficient production of bioethanol from SCG using an optimized liquid hot water (LHW) pretreatment combined with separate hydrolysis and fermentation (SHF) process. LHW pretreatment at 180 °C for 20 min with a high solid-to-liquid ratio (SLR) of 1:6 (w/v) was optimized to disrupt the lignocellulosic structure and retain high levels of fermentable sugars, which included mannose and glucose. This approach achieved a bioethanol concentration of 15.02 ± 0.05 g/L and a productivity rate of 1.252 g/(L·h), demonstrating the efficiency of this integrated process. Interestingly, the high SLR LHW pretreatment significantly reduces water usage and enhances product concentration, offering a promising, environmentally friendly, and economically viable method for industrial bioethanol production from SCGs without the necessity of detoxification. [ABSTRACT FROM AUTHOR]

This study reports on the application of an innovative plastering system that reuses organic waste, namely spent coffee grounds (SCG), to improve energy efficiency in historical buildings according to the European Green Deal. The case study was conducted in the village of Polizzi Generosa, selected from 21 small villages located in the extensive UNESCO Geopark of Madonie Park in Sicily. Over time, traditional plasters used in Madonie buildings have shown durability issues due to thermal and hygrometric stresses caused by significant temperature fluctuations in the area. Moreover, much of the considered architectural heritage lacks energy efficiency. Given the global increase in coffee production and the need for more sustainable waste management systems, this investigation proposes an ecological method to reuse SCG in plaster formulation, thereby enhancing the circular economy. To achieve this, many thermoplaster formulations were developed, and the best-performing one, considering both material and aesthetic compatibility with historical buildings, was selected for a real-world application. Additionally, virtual modeling and energy simulations were conducted to test the energy performance of a traditional building in Polizzi Generosa using SCG-based thermoplaster in comparison to traditional lime mortar and commercial alternatives. The real-world application demonstrated the technical feasibility of the process, and the energy simulations showed an improved building masonry energy performance of 0.788 W/m2K and an 11% improvement compared to traditional plaster. Results clearly indicate that SCG can be successfully reused to produce eco-friendly bio composite plasters, providing a more sustainable housing option. This approach offers a durable and cost-effective alternative for housing solutions that meet regulatory requirements for energy efficiency, serving as a smart, highly sustainable, and long-lasting choice for the construction sector. Finally, this result supports the research goal of transforming the 21 municipalities of Madonie into smart and green villages, with the "Smart Coffee-House" exemplifying intelligent rehabilitation processes of existing heritage buildings. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This research examined the potential for utilizing waste materials generated during the production of dishes/meals and organic waste. Specifically, it evaluated the use of orange peel (OP), spent coffee grounds (SCG), and waste cooking oil in the production of soaps. For the purposes of this study, homemade soaps were made from used food oils using the cold saponification method using sodium hydroxide. During the soap preparation, spent coffee grounds and orange peel were added to the samples in increasing concentrations of 1%, 2.5%, and 5%. The quality of the individual types of homemade soaps was evaluated on the basis of physicochemical properties such as pH, moisture, total alkalinity, total fatty matter, malondialdehyde content, fat content, foaminess, and hardness. All soaps produced using the cooking oil met the ISO quality criteria and reveal a high TFM content, low moisture content, and also very good foam stability and satisfactory foaming stability. However, no relationship was observed between the use of OP and SCG in soap production and these parameters. However, according to the ABTS test, OP and SCG significantly contributed to the antioxidant properties of the soaps, while SCG-impregnated soaps performed slightly better in this respect. Soaps with SCG also had the highest levels of flavonoids. On the other hand, the fillers used for the soap formulation reduced their hardness. All soaps showed 100% solubility in water, thus confirming the biodegradability of the product. This study demonstrated the novel potential of incorporating waste products like orange peel, spent coffee grounds, and waste cooking oil into homemade soaps, highlighting their contributions to its antioxidant properties and water solubility while ensuring high quality standards. [ABSTRACT FROM AUTHOR]

Spent coffee grounds (SCGs) constitute the main solid residue of the coffee brewing process. SCGs are generated in significant amounts daily, worldwide. The effective management of this waste through biological processes is still an unresolved problem. In this study, the application of hydrodynamic cavitation (HC) as a pre-treatment method for improving the biodegradability of SCGs suspended in municipal wastewater was proposed. An orifice plate with a conical concentric hole having inlet/outlet diameter of 3/10 mm was applied as the cavitation inducer. Three inlet pressures were chosen: 3, 5 and 7 bar. The effects in time intervals of 0, 5, 10, 20, 30 and 45 min were evaluated. The application of HC led to enhanced biodegradability for each case. The results of multi-criteria decision indicated that the most efficient combination in terms of biodegradability and energy usage was obtained at the pressure of 5 bar and duration of 20 or 30 min, depending on the adopted weights. The improvements of DOC/TOC (dissolved organic carbon/total organic carbon) ratio were 57% and 71%, as compared to the untreated samples. The release of caffeine was found at pressures of 5 and 7 bar. However, at 5 bar, this effect was noticed for the longest times, 30 and 45 min, respectively. [ABSTRACT FROM AUTHOR]

Spent coffee grounds (SCG) are a type of food waste and are produced in abundance around the world. However, their utilization as a soil organic amendment is challenging due to their phytotoxic effect. In the present work, the impact of agronomic biofortification on Dutch cucumbers was investigated using different chemically modified SCG and analyzing their effects on iron contents, their capacity for releasing antioxidants, and the production of short-chain fatty acids after in vitro digestion–fermentation. The results indicated variations in the iron contents and chemical compositions of cucumbers according to the treatment groups. Functionalized and activated hydrochar from SCG increased Fe levels in cucumbers. Although activated hydrochar obtained at 160 °C and functionalized with Fe showed the highest iron supply per serving, differences in antioxidant capacity and short-chain fatty acid production were observed between the groups. It is concluded that growing conditions and the presence of iron may significantly influence the contribution of these cucumbers to the dietary intake of nutrients and antioxidants, which could have important implications for human health and nutrition. [ABSTRACT FROM AUTHOR]

In this study, we conducted the first plasticization of wheat flour (WF) with the addition of choline chloride:urea (1:5 molar ratio) eutectic mixture as a plasticizer and spent coffee grounds (cf) as a filler. Thermoplastic wheat flour (TPWF) films were obtained via twin-screw extrusion and then thermocompression. Their physicochemical characterization included mechanical tests, dynamic mechanical thermal analysis (DMTA), and sorption tests. XRD analysis revealed that the eutectic plasticizer led to a high degree of WF amorphization, which affected the physicochemical properties of TPWF. The results indicated that it was easy for the TPWF biocomposites to undergo thermocompression even with a high amount of the filler (20 pph per flour). The addition of the cf into TPWF led to an increase in tensile strength and a decrease in the swelling degree of the biocomposites. Biodegradation tests in soil revealed that the materials wholly degraded within 11 weeks. Moreover, a study of cultivated plants indicated that the biocomposites did not exhibit a toxic influence on the model rowing plant. [ABSTRACT FROM AUTHOR]

The key technological implementation of sodium-ion batteries is converting biomass-derived hard carbons into effective anode materials. This becomes feasible if appropriate knowledge of the relations between the structure of carbonized biomass products, the mineral ash content in them, and Na storage properties is gained. In this study, we examine the simultaneous impact of the ash phase composition and carbon structure on the Na storage properties of hard carbons derived from spent coffee grounds (SCGs). The carbon structure is modified using the pre-carbonization of SCGs at 750 °C, followed by annealing at 1100 °C in an Ar atmosphere. Two variants of the pre-carbonization procedure are adopted: the pre-carbonization of SCGs in a fixed bed and CO2 flow. For the sake of comparison, the pre-carbonized products are chemically treated to remove the ash content. The Na storage performance of SCG-derived carbons is examined in model two and three Na-ion cells. It was found that ash-containing carbons outperformed the ash-free analogs with respect to cycling stability, Coulombic efficiency, and rate capability. The enhanced performance is explained in terms of the modification of the carbon surface by ash phases (mainly albite) and its interaction with the electrolyte, which is monitored by ex situ XPS. [ABSTRACT FROM AUTHOR]

Composting of mixed medicinal plant waste was performed with the addition of mixture of plant growth promoting bacteria (PGPB), including Streptomyces sp., Paenybacillus sp., Bacillus sp., and Hymenobacter sp., and portions of spent coffee grounds (SCG). To assess the maturity and quality parameters of the compost, chemical and biological parameters (C/N ratio, loss of organic matter, CO2 production, dehydrogenase activity (DHA), and phytotoxicity) were evaluated during the three months of the composting process. The results revealed that the control sample (without the addition of SCG and PGPB) had evidently lower values of DHA during the entire monitoring period in comparison to other samples, indicating lower microbial activity in the compost mixture. Also, according to the released CO2, the composting process was accelerated in all samples where the SCG and PGPB were added, enabling a reduction in time needed for mixed plant waste to decompose. The germination index (GI) of the tested seeds indicated that the produced compost was acceptable and safe, with regard to all of the evaluated samples. However, at the end of the process the samples contained SCG and PGPB, which caused an increase of more than 50% of the GI in comparison to the control sample, expressing a high phyto-stimulant effect and improving the biofertilization impact. [ABSTRACT FROM AUTHOR]

The global population is expected to increase by nearly 2 billion individuals over the next three decades, leading to a significant surge in waste generation and environmental challenges. To mitigate these challenges, there is a need to develop sustainable solutions that can effectively manage waste generation and promote a circular economy. Mycelium-based composites (MBCs) are being developed for various applications, including packaging, architectural designs, sound absorption, and insulation. MBCs are made by combining fungal mycelium with organic substrates, using the mycelium as a natural adhesive. Mycelium, the vegetative part of fungi, can be grown on various organic feedstocks and functionalized into a range of diverse material types that are biobased and thus more sustainable in their production, use, and recycling. This work aims to obtain mycelium-based composites with acoustic absorption properties, using coffee grounds and agricultural waste as raw materials. The topic approached presents a new method of recovering spent coffee grounds that does not involve high production costs and reduces two current environmental problems: noise pollution and abundant waste. Measurements of the normal-incidence sound absorption coefficient were presented and analyzed. Mycelium-based composites offer an innovative, sustainable approach to developing bio-composite sound-absorbing surfaces for interior fittings. The material by Ganoderma lucidum exhibits exceptional sound-absorbing properties at frequencies below 700 Hz, which is a crucial aspect of creating sound-absorbing materials that effectively absorb low-frequency sound waves. The modular construction system allows for a high degree of flexibility to adapt to short-term changes in the workplace. [ABSTRACT FROM AUTHOR]

The reuse potential for the large annual production of spent coffee grounds (SCGs) is underexploited in most world regions. Hydrochars from SCGs produced via hydrothermal carbonization (HTC) have been recognized as a promising solid fuel alternative. To increase demand, optimization of the HTC and two post-treatment processes, washing and agglomeration, were studied to improve hydrochar in terms of energetic properties, minimizing unwanted substances, and better handling. HTC experiments at three scales (1–18.75 L) and varying process conditions (temperature T (160–250 °C), reaction time t (1–5 h), and solid content %So (6–20%) showed that the higher heating value (HHV) can be improved by up to 46%, and most potential emissions of trace elements from combustion reduced (up to 90%). The HTC outputs (solid yield—SY, HHV, energy yield—EY) were modeled and compared to published genetic programming (GP) models. Both model types predicted the three outputs with low error (<15%) and can be used for process optimization. The efficiency of water washing depended on the HTC process temperature and type of aromatics produced. The furanic compounds were removed (69–100%; 160 °C), while only 34% of the phenolic compounds (240 °C) were washed out. Agglomeration of both wet SCG and its hydrochar is feasible; however, the finer particles of washed hydrochar (240 °C) resulted in larger-sized spherical pellets (85% > 2000–4000 µm) compared to SCGs (only 4%). [ABSTRACT FROM AUTHOR]

Polylactic Acid (PLA) is a biodegradable polymer, but the cost of PLA is not competitive compared to polyolefins. The development of bioplastic composites by blending PLA with spent coffee grounds (SCG) and thermoplastic starch (TPS) is an effective way to reduce the cost of PLA. This study aimed to investigate and evaluate the feasibility of using SCG to develop bioplastic composite materials with a blend of PLA and TPS. Bioplastics were fabricated with various SCG contents (5, 10, 15 wt%). The physical and mechanical characteristics of the bioplastic composite decreased as the SCG content increased owing to the higher aggregation caused by SCG dust. However, the bioplastics manufactured with the addition of SCG exhibited enhanced crystallinity, resulting in enhanced thermal properties compared to the composites without SCG. The best characteristics of bioplastics, obtained with a 5% SCG addition, were as follows: water vapor transmission rate of 1276 g d/m2, water vapor permeability (WVP) of 1.86256 × 10−7 g/ms Pa, Young's modulus of 420 MPa, elongation of 2.59%, and tensile strength of 5 MPa. Based on the results obtained, it can be concluded that the addition of SCG is not recommended for improving the physical and mechanical properties of bioplastics. However, owing to its large content of organic compounds, SCG represents a promising and low-cost functional material that can be exploited in the development of various value-added products. [ABSTRACT FROM AUTHOR]

The aim of this work concerned the production of an active food packaging suitable for refrigerated foods. Polylactic-acid-based films were produced by optimizing the solvent casting technique and testing different loadings of extracts obtained from spent coffee grounds. Indeed, an extract obtained by high-pressure and -temperature extraction (HPTE) and a further purified extract by liquid–liquid extraction (LLE) were separately used as active agents, and the effects on packaging features and active compounds migration were analyzed. The selected active agents showed antioxidant and lipid peroxidation inhibition effects on food simulants (peroxide values of 9.2 ÷ 12.0 meqO2/kg extra virgin olive oil), demonstrating the possibility of enhancing food shelf life. In addition, significant effects on the packaging structure due to the presence of the extract were observed, since it can enhance gas barrier properties of the polymer (O2 permeability of 1.6 ÷ 1.3 × 10−9 cm2/s) and confer better processability. In general, the HPTE extract exhibited better performances than the further purified extract, which was due to the presence of a complex pool of antioxidants and the browning effect on the film but a limited loading capacity on the polymer (840 μg caffeine/g PLA), while higher loading capabilities were enabled using LLE extract. [ABSTRACT FROM AUTHOR]

In a field experiment, composted coffee waste (CW) was used as soil amendment at three different rates (2%, 4%, and 8%) in plots cultivated with wheat; the effects on the soil nematode community and plant growth were studied. By sampling twice, i.e., three and six months after the application of treatments (3MAA and 6MAA), the duration of these effects was also evaluated. Treatment using composted coffee waste (CW) led to an increased abundance of all soil nematodes, especially of bacterivores and fungivores, probably via a bottom-up effect of CW on the soil community. The most-affected genera were the enrichment opportunists Panagrolaimus and Rhabditis, which increased after CW addition in a dosage-dependent way at 3MAA, while at 6MAA they were replaced by general opportunists, mainly bacterivorous and fungivorous genera; a nematotoxic effect of CW was also observed in the 6MAA condition. The nematode indices and the metabolic footprint indicated an enriched and vigorous soil three months after CW addition and a lower enrichment status of the soil together with a higher fungal participation in the decomposition pathway six months after treatments. However, in the 6 MAA condition, the soil nutrient values were higher in the CW-treated plots. None of our treatments inhibited or enhanced plant growth. [ABSTRACT FROM AUTHOR]

Spent coffee grounds (SCGs) are currently considered abandoned landfill waste despite retaining valuable organic compounds, especially with a high protein content of 16.64 ± 0.13 g/g dried SCGs and a high oil content of 15.48 ± 0.17 g/g dried SCGs. As a result, SCGs could serve as a potential source of valuable ingredients. However, utilizing a single technical strategy of alternative green extractions was insufficient for extracting the target compounds and hydrolyzing proteins. This work aimed to optimize the operating parameters of enzyme-assisted extraction (EAE), microwave-assisted extraction (MAE), and subcritical water extraction (SWE) using a response surface methodology. The results showed that EAE, at a papain-to-substrate ratio (E/S) of 0.5 and a duration of 15 min, generated a %DH of 93.39% and provided a water soluble protein concentration (WSPC) in the range of 400 to 800 µg/mL. Moreover, MAE provided a maximum %DH of 9.72% at 600 watts and 10 min, while SWE produced a maximum %DH of 13.41% at 160 °C in 17.5 min. However, the WSPCs of MAE and SWE extracts were comparable at ~250 µg/mL. The combination MAE−SWE enhanced the %DH of hydrolysates by more than the combined SWE−MAE, SWE, and MAE. However, the effects of differential hydrolysis on bioactivity are not directly correlated with %DH. In this study, the highest antioxidant activity was found at an E/S of 0.5 and in 15 min for EAE, at 350 W and in 10 min for MAE, and at 160 °C and in 30 min for SWE. This work demonstrated that the valorization of SCGs not only reduces the amount of waste but also yields functional cosmeceutical and nutraceutical ingredients. [ABSTRACT FROM AUTHOR]

The aim of this research is to study the use of the spent coffee grounds (SCGs) as a novel and environmentally friendly corrosion inhibitor. The oily fraction obtained from decoction extraction was subjected to analysis using Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The inhibitive action of SCG extract on the corrosion of copper in a 3 wt% NaCl solution was studied via potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The research findings elucidate that the extract derived from SCGs functions as a cathodic inhibitor, primarily impeding the diffusion of oxygen molecules towards the copper substrate. Notably, the inhibitory effectiveness exhibits an improvement with ascending concentrations of the SCG extract. This augmentation culminates in a remarkable 96% inhibition efficiency when the SCG extract concentration reaches 0.6 g/L. Furthermore, it is observed that the SCG extract undergoes adsorption onto the copper surface, a phenomenon that conforms to the Langmuir adsorption isotherm. [ABSTRACT FROM AUTHOR]

The present study investigated the possibility of spent coffee ground (SCG) transformation to a cellulose-based enzyme immobilization carrier using a multistep extraction procedure. In the first step, SCGs were extracted with n-hexane by Soxhlet extraction in order to obtain SCG oil, while the remaining solid residue was subjected to continuous solvent flow sequential subcritical extraction with 96% and 50% ethanol and water. Afterwards, the obtained solid residue was subjected to alkaline liquefaction with 8% NaOH in order to remove lignin and produce cellulose-enriched SCGs as a potential enzyme immobilization carrier. Multistep extraction transformation of SCGs was monitored by chemical analysis of extracts and obtained solid residues. Soxhlet extraction of 100 g of SCGs yielded 10.58 g of SCG oil rich in linoleic and palmitic acid, while continuous solvent flow sequential subcritical extraction of 100 g of defatted SCGs yielded a total of 1.63 g of proteins, 5.58 g of sugars, 204 mg of caffeine, 76 mg of chlorogenic acid, and 11.97 mg of 5-(hydroxymethyl)furfural. Alkaline liquefaction of 100 g of sequentially extracted defatted SCGs by 8% NaOH yielded 7.45 g of proteins, 8.63 g of total polyphenols, 50.73 g of sugars, and 20.83 g of cellulose-enriched SCGs. Based on the characteristics of cellulose-enriched SCGs including a volume-weighted mean particle size of 277 μm, relative narrow particle size distribution with a span value of 1.484, water holding capacity of 7.55 mL/g, and a lack of carrier leakage, it could be safely concluded that produced cellulose-enriched SCGs fulfills criteria to be used as potential enzyme immobilization carrier. Overall, it seems that the proposed multistep extraction transformation of SCGs has great potential to be used for the production of several high-value added products. [ABSTRACT FROM AUTHOR]

Supplementary cementitious materials are considered a viable and affordable way to reduce CO2 emissions from the cement industry's perspective since they can partially or nearly entirely replace ordinary Portland cement (OPC). This study compared the impact of adding spent coffee grounds (SCGs), fly ash (FA), and volcanic ash (VA) to two types of cement: OPC and calcium sulfoaluminate cement (CSA). Cement samples were characterized using compressive strength measurements (up to 210 days of curing), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), X-ray diffraction (XRD), attenuated total reflection infrared spectroscopy, and hydration temperature measurements. In all the studied systems, the presence of SCGs reduced compressive strength and delayed the hydration process. CSA composite cement containing 3.5% SCGs, 30% FA, and 30% VA showed compressive strength values of 20.4 MPa and 20.3 MPa, respectively, meeting the minimum requirement for non-structural applications. Additionally, the results indicate a formation of cementitious gel, calcium silicate hydrate (C-S-H) in the OPC-based composite cements, and calcium alumino-silicate hydrate (C-A-S-H) as well as ettringite in the CSA-based composite cements. [ABSTRACT FROM AUTHOR]

Previous studies have attributed both phytotoxicity and the capacity to mobilize nutrient elements to the presence of polyphenols and melanoidins in spent coffee grounds (SCG) and SCG-hydrochars obtained through hydrothermal carbonization (HTC). This work aimed to evaluate SCG and two SCG-hydrochars obtained at 160 and 200 °C that were functionalized with Zn salts (bio-chelates), to achieve the in vitro biofortification of lettuce. Two application modes were established: (1) a fixed Zn concentration of 10 mg kg−1 of soil and (2) a fixed dose of 0.5% bio-product. Soil alone (control A) and commercial chelates (control B) were used as controls. Outcomes showed that SCG-hydrochars retain the capacity to mobilize Zn compared to SCG. However, the chelating capacity was reduced (Zn: 94%) and the toxicity was significantly increased (p < 0.05) with higher temperatures of HTC (200 °C). Both fresh and dry lettuce weights were less affected at doses of 0.5% of bio-product and registered a maximum increase of 136% of Zn in the plant content. The present study approaches the possibility of using these by-products as bioinorganic fertilizers at subtoxic doses, although more research is needed. [ABSTRACT FROM AUTHOR]

Coffee is one of the most popular beverages, with around 10.5 million tons manufactured annually. The same amount of spent coffee grounds (SCGs) might harm the environment if disposed of carelessly. On the other hand, pesticide contamination in food and biowaste is a rising problem. Because pesticides are hazardous and can cause serious health consequences, it is critical to understand how they interact with food biowaste materials. However, it is also a question if biowaste can be used to remediate rising pesticide residues in the environment. This study investigated the interactions of SCGs with the organophosphate pesticides malathion (MLT) and chlorpyrifos (CHP) and addressed the possibility of using SCGs as adsorbents for the removal of these pesticides from water and fruit extracts. The kinetics of MLT and CHP adsorption on SCGs fits well with the pseudo-first-order kinetic model. The Langmuir isotherm model best describes the adsorption process, giving the maximal adsorption capacity for MLT as 7.16 mg g−1 and 7.00 mg g−1 for CHP. Based on the thermodynamic analysis, it can be deduced that MLT adsorption on SCGs is exothermic, while CHP adsorption is an endothermic process. The adsorption efficiency of MLT and CHP using SCGs in a complicated matrix of fruit extracts remained constant. The neurotoxicity results showed that no more toxic products were formed during adsorption, indicating that SCGs are a safe-to-use adsorbent for pesticide removal in water and fruit extracts. [ABSTRACT FROM AUTHOR]

Coffee waste is often viewed as a problem, but it can be converted into value-added products if managed with clean technologies and long-term waste management strategies. Several compounds, including lipids, lignin, cellulose and hemicelluloses, tannins, antioxidants, caffeine, polyphenols, carotenoids, flavonoids, and biofuel can be extracted or produced through recycling, recovery, or energy valorization. In this review, we will discuss the potential uses of by-products generated from the waste derived from coffee production, including coffee leaves and flowers from cultivation; coffee pulps, husks, and silverskin from coffee processing; and spent coffee grounds (SCGs) from post-consumption. The full utilization of these coffee by-products can be achieved by establishing suitable infrastructure and building networks between scientists, business organizations, and policymakers, thus reducing the economic and environmental burdens of coffee processing in a sustainable manner. [ABSTRACT FROM AUTHOR]

With the increasing consumption of coffee beverages, an increased amount of food waste—spent coffee grounds (SCG)—is generated and disposed into landfills or combusted in incinerators. SCG are characterized as a highly polluting substance with partial toxicity due to the presence of caffeine, tannins, and polyphenols. It also contains 15% of oil on average, and its potential for biodiesel production is thus considerable. The aim of the presented work is to evaluate the possibility and technical potential of biodiesel production from the SCG oil (SCGO) by esterification and transesterification reaction. According to the characterization of the studied SCGO, this stream must be adjusted and purified to be utilized in the existing biodiesel production plant. Fatty acids (FA) represent 85.85% of the SCGO, with two dominant FAs—linoleic and palmitic acids. The necessity of removal and disposal of unsaponifiable matter, which accounts for 15% of the SCGO content, must be highlighted when producing biodiesel from the SCG. The objective of this research was the comparison of different biodiesel production processes, where a two-step transesterification process has been identified as the most successful method for biodiesel production from the SCGO with the highest ester content of 89.62% and the lowest content of unsaponifiable and unidentified matter in the final product. The novelty of the analyses is a characterization of the d unsaponifiable matter present in the SCGO, and the article highlights the importance of progression to be considered when evaluating the technical potential of the SCG biodiesel production integrated into a biorefinery. Nevertheless, the SCG biodiesel can contribute to fulfilling the mandatory share of advanced biofuel in the fuel energy mix given by national legislation and contribution to the circular economy approach of biorefineries. [ABSTRACT FROM AUTHOR]

This paper explores the transformation of biowastes from food industry and agriculture into high-value products through four examples. The objective is to provide insight into the principles of green transition and a circular economy. The first two case studies focus on the waste generated from the production of widely consumed food items, such as beer and coffee, while the other two examine the potential of underutilized plants, such as burdock and willow, as sources of valuable compounds. Phenolic compounds are the main target in the case of brewer's spent grain, with p-coumaric acid and ferulic acid being the most common. Lipids are a possible target in the case of spent coffee grounds with palmitic (C16:0) and linoleic (C18:2) acid being the major fatty acids among those recovered. In the case of burdock, different targets are reported based on which part of the plant is used. Extracts rich in linoleic and oleic acids are expected from the seeds, while the roots extracts are rich in sugars, phenolic acids such as chlorogenic, caffeic, o-coumaric, syringic, cinnamic, gentisitic, etc. acids, and, interestingly, the high-value compound epicatechin gallate. Willow is well known for being rich in salicin, but picein, (+)-catechin, triandrin, glucose, and fructose are also obtained from the extracts. The study thoroughly analyzes different extraction methods, with a particular emphasis on cutting-edge green technologies. The goal is to promote the sustainable utilization of biowaste and support the green transition to a more environmentally conscious economy. [ABSTRACT FROM AUTHOR]

In the present work, the modification of spent coffee grounds (SCG) hydrolysate composition by mixed cultures of a non-Saccharomyces yeast, Lachancea thermotolerans, and a lactic acid bacterium, Lactiplantibacillus plantarum, as well as their interactions, were evaluated. It was found that L. plantarum inhibited the growth and survival of L. thermotolerans as compared with that in the yeast alone. On the other hand, the growth and survival of L. plantarum was slowed in sequential fermentation, but not in co-culture. Compared with co-culture, higher ethanol content, less residual sugars, and less acetic and succinic acids were found in sequential fermentation. In addition, lower amounts of caffeine and phenolic acids (e.g., ferulic, caffeic, and p-coumaric acids) were obtained in mixed (co- and sequential) cultures with corresponding levels of volatile phenols relative to the yeast monoculture. Moreover, co-culturing resulted in the highest contents of total alcohols (ethanol excluded) and total esters. Therefore, mixed culturing of L. plantarum and L. thermotolerans presented positive effects on the chemical constituents of fermented SCG hydrolysates, which might be a new alternative approach to valorizing the SCG into novel alcoholic drinks with different ethanol and flavor constituents. [ABSTRACT FROM AUTHOR]

This article presents the results of a study on metallurgical slag reduction using biomass such as Spent Coffee Grounds (SCGs). The proposed solution is a new aspect of searching for alternatives to standard reducers used in pyrometallurgical processes of metal production. Its gasification yields significant amounts of hydrocarbons, which are excellent reducing agents in such processes. The research results of copper slag reduction with the use of SCG biomass indicate this process is characterised by lower carbon dioxide emissions compared with the process using solid fuels such as coke and coke breeze. The addition of SCG as the reducer ensures the decrease in copper content in the slag to 0.32 wt.%, which corresponds to the increase of so-called relative decopperisation degree even up to 96.9%. As the decopperisation degree of slag increases, significantly more intense reduction in lead oxides during the reduction process is observed. The smallest lead content in waste slag of 0.91 wt.% was obtained for the slag reduction process with 7.56 wt.% of SCG as the reducer and the process duration of 1.5 h. [ABSTRACT FROM AUTHOR]

Due to the worldwide consumption of coffee, many tons of spent coffee grounds (SCGs) are discarded each year, as a by-product of coffee preparation. Not only their disposal is costly, but also it may cause the release of compounds that can endanger the environment. However, there are valuable chemical compounds that can be extracted from SCGs and used in the food industry. The aim of this study was to investigate the main parameters affecting the extraction of caffeine and polyphenols (i.e., chlorogenic acid, neochlorogenic acid, and caffeic acid) and to evaluate the antioxidant properties of the extracts. To this end, extraction solvent, temperature, time, and liquid-to-solid ratio were studied. A response surface methodology was used to optimize the extraction process. According to the results, the caffeine content of the optimum extract was found to be 6.14 mg/g in dry SCGs, the total polyphenol content was 19.85 mg gallic acid equivalents/g, while the ferric reducing antioxidant power and DPPH scavenging values were 136.69 μmoL ascorbic acid equivalents/g and 230.41 μmoL DPPH/g, respectively. The experimental values were in close agreement with the predicted ones, highlighting the potential of SCGs to be used for the isolation of bioactive compounds with the proposed extraction procedure. [ABSTRACT FROM AUTHOR]

As an everyday beverage, coffee is consumed worldwide, generating a high amount of waste after brewing, which needs attention for its disposal. These residues are referred to as spent coffee grounds (SCGs), which have been shown to have applications as polymers/composites precursors, biofuels, and biofertilizers. This review focuses on agricultural applications usually based on organic matter to fertilize the soil and consequently improve plant growth. To date, SCGs have been shown to exhibit outstanding performance when applied as soil amendment and composting because it is a nutrient-rich organic waste without heavy metals. Therefore, this review presents the different options to use SCGs in agriculture. First, SCG composition using different characterization techniques is presented to identify the main components. Then, a review is presented showing how SCG toxicity can be resolved when used alone in the soil, especially at high concentrations. In this case, SCG is shown to be effective not only to enhance plant growth, but also to enhance nutritional values without impacting the environment while substituting conventional fertilizers. Finally, a conclusion is presented with openings for future developments. [ABSTRACT FROM AUTHOR]

Biofuels have become a source of renewable energy to offset the use of fossil fuels and meet the demand for electricity, heat, and cooling in the industrial sector. This study aims to (a) develop a simulation of a trigeneration system based on a gas turbine cycle and an absorption chiller unit, using biomass and syngas from spent coffee grounds (SCGs) to replace the conventional system currently supplying the energy requirements of an instant coffee plant located in Guayaquil, Ecuador, and (b) carry out an exergoeconomic analysis of the simulated system to compare the effects of different fuels. The results showed an increase in the exergetic efficiency from 51.9% to 84.5% when using a trigeneration system based on biomass instead of the conventional non-integrated system. Furthermore, the biomass-based system was found to have the lowest operating costs ($154.7/h) and the lowest heating, cooling, and power costs ($10.3/GJ, $20.2/GJ, and $23.4/GJ, respectively). Therefore, the results of this analysis reveal that using SCGs as biofuel in this instant coffee plant is feasible for producing steam, chilled water, and power. [ABSTRACT FROM AUTHOR]

Coffee is a popular and widely consumed beverage worldwide, with epidemiological studies showing reduced risk of cardiovascular disease, cancers and non-alcoholic fatty liver disease. However, few studies have investigated the health effects of the post-brewing coffee product, spent coffee grounds (SCG), from either hot- or cold-brew coffee. SCG from hot-brew coffee improved metabolic parameters in rats with diet-induced metabolic syndrome and improved gut microbiome in these rats and in humans; further, SCG reduced energy consumption in humans. SCG contains similar bioactive compounds as the beverage including caffeine, chlorogenic acids, trigonelline, polyphenols and melanoidins, with established health benefits and safety for human consumption. Further, SCG utilisation could reduce the estimated 6–8 million tonnes of waste each year worldwide from production of coffee as a beverage. In this article, we explore SCG as a major by-product of coffee production and consumption, together with the potential economic impacts of health and non-health applications of SCG. The known bioactive compounds present in hot- and cold-brew coffee and SCG show potential effects in cardiovascular disease, cancer, liver disease and metabolic disorders. Based on these potential health benefits of SCG, it is expected that foods including SCG may moderate chronic human disease while reducing the environmental impact of waste otherwise dumped in landfill. [ABSTRACT FROM AUTHOR]

Upcycling is a modern trend in the cosmetic sector, focusing on by-products reuse and waste reduction. Consumers are more aware of the origin of cosmetic products and their environmental impact, promoting the upcycling phenomenon. Converting these raw materials into products of higher quality or value contributes to the final product's sustainability. In fact, several agri-food by-products that are typically discarded have generated great interest, due to their value-added compounds with high functionality and/or bioactivity. Coffee is well known as a cosmetic ingredient, particularly due to the presence of phenolic compounds, such as chlorogenic acids, and caffeine. Caffeine is widely used in cosmetic formulations due to its photoprotector and anti-aging properties, as well as lipolytic action in cellulitis, and hair regrowth. Chlorogenic acids are powerful antioxidants and exhibit anti-aging and photoprotector abilities. Coffee by-products, such as coffee beans, possess these bioactive compounds and other chemical characteristics that can provide functional properties in cosmetic formulations. Coffee silverskin and spent coffee grounds are high-volume by-products of the coffee industry. Their use has been explored in different cosmetic formulations demonstrating safety, stability, acceptability as well as skin improvement, thus supporting their valorization as natural and sustainable new ingredients in skincare products. [ABSTRACT FROM AUTHOR]

In the context of the circular economy, used coffee grounds were transformed into powdered activated carbon by chemical activation using potassium hydroxide. Its characterisation was conducted in comparison with that of a commercial activated carbon by scanning electron microscopy (SEM) coupled with energy dispersive X-ray microanalysis (EDX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Boehm titration, and point zero charge (pHPZC) and by determination of the methylene blue number (MBN) and the iodine number (IN). Performance of the prepared activated carbon was tested in the adsorption of the cationic dye crystal violet (CV) and hexavalent chromium. Batch adsorption tests were carried out and the effects of operating parameters were studied. The results collected on the adsorption kinetics show that the adsorption followed pseudo-second order kinetics and that the Langmuir isotherm best fits the equilibrium data for crystal violet and hexavalent chromium. The thermodynamic study showed that the adsorption of both adsorbates is spontaneous and exothermic and leads to a decrease in disorder at the solid–liquid interfaces. These results indicate that this activated carbon can be used as an alternative adsorbent to remove cationic dyes and heavy metals from aqueous solutions. [ABSTRACT FROM AUTHOR]

Peat is the predominant component of growing media in soilless horticultural systems. However, peat extraction from peatlands destroys these fragile ecosystems and emits greenhouse gas emissions (GHG). Peat replacement by other growing media is, thus, paramount to ensure a more sustainable horticultural sector. This study investigated the agronomical performances of two spent coffee ground-based composts with and without biochar, during three different stages of tomato (Solanum lycopersicum L.) development: seeds germination (0–6 days), seedling development (7–49 days), and plant-to-fruit maturity (36–100 days). The two composts were used as peat replacement and mixed with peat at four different volumetric proportions: 100% (pure compost), 50%, 30%, and 15%. The substrates had a stimulant effect on seed germination but induced stunted growth due to the elevated electrical conductivity. For the latest stages of plant development, compost with and without biochar mixed with peat at 50% promoted an increase in fruit production of 60.8% and 100.3%, compared to the control substrate. The present study provides evidence that combining biochar with spent coffee ground compost represents a potential alternative for peat-based growing media promoting a circular production model in the horticultural sector, but the results are dilution- and plant development stage-dependent. [ABSTRACT FROM AUTHOR]

The valuable products that can be isolated from spent coffee ground (SCG) biomass consist of a high number of bioactive components, which are suitable for further application as raw materials in various production chains. This paper presents the potential value of the SCG obtained from large and local coffee beverage producers, for the production of valuable, biologically active products. Despite its high potential, SCG has not been utilized to its full potential value, but is instead discarded as waste in landfills. During its decomposition, SCG emits a large amount of CO2 and methane each year. The main novelty of our work is the implementation of sequential extraction with solvents of increased polarity that allows for the maximal removal of the available extractives. In addition, we have compared different extraction techniques, such as conventional and Soxhlet extraction, with more effective accelerated solvent extraction (ASE), which has seen relatively little use in terms of SCG extraction. By comparing these extraction methods and highlighting the key differences between them in terms of extraction yield and obtained extract composition, this work offers key insights for further SCG utilization. By using sequential and one-step accelerated solvent extraction, it is possible to obtain a significant number of extractives from SCG, with a yield above 20% of the starting biomass. The highest yield is for coffee oil, which is obtained with n-hexane ranging between 12% and 14% using accelerated solvent extraction (ASE) according to the scheme: n-hexane→ethyl acetate→60% ethanol. Using single-stage extraction, increasing the ethanol concentration also increases the total phenolic content (TPC) and it ranges between 18.7–23.9 Gallic acid equivalent (GAE) mg/g. The iodine values in the range of 164–174 using ASE and Soxhlet extraction shows that the hexane extracts contain a significant amount of unsaturated fatty acids; coffee oils with a low acid number, in the range of 4.74–6.93, contain few free fatty acids. The characterization of separated coffee oil has shown that it mainly consists of linoleic acid, oleic acid, palmitic acid, stearic acid and a small number of phenolic-type compounds. [ABSTRACT FROM AUTHOR]

In the context of today's needs for environmental sustainability, it is important to develop new materials that are based on renewable resources and biodegrade at the end of their life. Bioplastics reinforced by agricultural waste have the potential to cause a revolution in many industrial applications. This paper reports the physical properties and crystallization kinetics of biocomposite films based on poly(L-lactic acid) (PLLA) and 10 wt.% of spent coffee grounds (SCG). To enhance adhesion between the PLLA matrix and SCG particles, a compatibilizing agent based on itaconic anhydride (IA)-grafted PLLA (PLLA-g-IA) was prepared by reactive extrusion using dicumyl peroxide (DCP). Furthermore, due to the intended application of the film in the packaging industry, the organic plasticizer acetyl tributyl citrate (ATBC) is used to improve processing and increase ductility. The crystallization behavior and thermal properties were observed by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Crystallinity degree increased from 3,5 (neat PLLA) up to 48% (PLLA/PLLA-g-IA/ATBC/SCG) at the highest cooling rate. The physical properties were evaluated by tensile testing and dynamic mechanical analysis (DMA). The combination of the compatibilizer, SCG, and ATBC led to a synergistic effect that positively influenced the supramolecular structure, internal damping, and overall ductility of the composite films. [ABSTRACT FROM AUTHOR]

Spent coffee grounds are a promising bioresource that naturally contain around 50 wt% moisture which requires, for a valorization, a drying step of high energy and economic costs. However, the natural water in spent coffee grounds could bring new benefits as a co-solvent during the supercritical CO2 extraction (SC-CO2). This work reports the influence and optimization of pressure (115.9–284.1 bars), temperature (33.2–66.8 °C), and moisture content (6.4–73.6 wt%) on simultaneous extraction of lipids and polar molecules contained in spent coffee grounds by supercritical CO2 (SC-CO2) using Central Composite Rotatable Design and Response Surface Methodology. The results show that for lipids extraction, pressure is the most influent parameter, although the influence of moisture content is statistically negligible. This suggests that water does not act as barrier to CO2 diffusion in the studied area. However, moisture content is the most influent parameter for polar molecules extraction, composed of 99 wt% of caffeine. Mechanism investigations highlight that H2O mainly act by (i) breaking caffeine interactions with chlorogenic acids present in spent coffee grounds matrix and (ii) transferring selectively caffeine without chlorogenic acid by liquid/liquid extraction with SC-CO2. Thus, the experiment for the optimization of lipids and polar molecules extraction is performed at a pressure of 265 bars, a temperature of 55 °C, and a moisture content of 55 wt%. [ABSTRACT FROM AUTHOR]

Coffee is one of the world's most popular beverages, and its consumption generates copious amounts of waste. The most relevant by-product of the coffee industry is the spent coffee grounds, with 6 million tons being produced worldwide per year. Although generally treated as waste, spent coffee grounds are a rich source of several bioactive compounds with applications in diverse industrial fields. The present work aimed at the analysis of spent coffee grounds from different geographical origins (Guatemala, Colombia, Brazil, Timor, and Ethiopia) for the identification of bioactive compounds with industrial interest. For this purpose, the identification and quantification of the bioactive compounds responsible for the antioxidant activity attributed to the spent coffee grounds were attempted using miniaturized solid-phase extraction (µ-SPEed), combined with ultrahigh-performance liquid chromatography with photodiode array detection (UHPLC-PDA). After validation of the µ-SPEed/UHPLC-PDA method, this allowed us to conclude that caffeine and 5-caffeoylquinic acid (5-CQA) are the most abundant bioactive compounds in all samples studied. The total phenolic content (TPC) and antioxidant activity are highest in Brazilian samples. The results obtained show that spent coffee grounds are a rich source of bioactive compounds, supporting its bioprospection based on the circular economy concept closing the loop of the coffee value chain, toward the valorization of coffee by-products. [ABSTRACT FROM AUTHOR]

Spent coffee grounds (SCGs) are a promising substrate that can be valorized by biotechnological processes, such as for short-chain organic acid (SCOA) production, but their complex structure implies the application of a pretreatment step to increase their biodegradability. Physicochemical pretreatments are widely studied but have multiple drawbacks. An alternative is the application of biological pretreatments that include using fungi Trametes versicolor and Paecilomyces variotii that naturally can degrade complex substrates such as SCGs. This study intended to compare acidic and basic hydrolysis and supercritical CO2 extraction with the application of these fungi. The highest concentration of SCOAs, 2.52 gCOD/L, was achieved after the acidification of SCGs pretreated with acid hydrolysis, but a very similar result, 2.44 gCOD/L, was obtained after submerged fermentation of SCGs by T. versicolor. This pretreatment also resulted in the best acidification degree, 48%, a very promising result compared to the 13% obtained with the control, untreated SCGs, highlighting the potential of biological pretreatments. [ABSTRACT FROM AUTHOR]

In this study, alternative uses for lignocellulosic waste by considering them a source of eco-friendly and renewable energy generation with the application of the anaerobic digestion of treated and untreated waste for biogas and biohydrogen generation were investigated. The diluted sulfuric acid method was used for both the substrates and inoculum. Hydrogen production was absent when untreated spent coffee grounds (SCG) and alcohol waste (AW) were both used with the inoculum at pH 5.5 and pH 7.5. Meanwhile, the highest biogas yield of 320 dm3 kg V.S−1 was obtained when using AW at pH 7.5, with a 190 dm3 kg V.S−1 yield of methane. Instead, hydrogen production was observed when initially 4% (w/v) and 6% (w/v) SCG-containing hydrolysates were used as the substrates at pH 5.5, yielding 2.9 ± 0.09 dm3 kg V.S−1 and 3.85 ± 0.12 dm3 kg V.S−1, respectively. The further optimization of pretreatment technologies and pH control could lead to increased and prolonged hydrogen production. [ABSTRACT FROM AUTHOR]

Nanotechnology has become increasingly important in modern society, and nanoparticles are routinely used in many areas of technology, industry, and commercial products. Many species of nanoparticle (NP) are typically synthesized using toxic or hazardous chemicals, making these methods less environmentally friendly. Consequently, there has been growing interest in green synthesis methods, which avoid unnecessary exposure to toxic chemicals and reduce harmful waste. Synthesis methods which utilize food waste products are particularly attractive because they add value and a secondary use for material which would otherwise be disposed of. Here, we show that spent coffee grounds (SCGs) that have already been used once in coffee brewing can be easily used to synthesize gold and silver NPs. SCGs derived from medium and dark roasts of the same bean source were acquired after brewing coffee by hot brew, cold brew, and espresso techniques. The total antioxidant activity (TAC) and total caffeoylquinic acid (CQA) of the aqueous SCG extracts were investigated, showing that hot brew SCGs had the highest CQA and TAC levels, while espresso SCGs had the lowest. SCG extract proved effective as a reducing agent in synthesizing gold and silver NPs regardless of roast or initial brew method. [ABSTRACT FROM AUTHOR]

Acidogenic fermentation (AF) is often applied to wastes to produce short-chain organic acids (SCOAs)—molecules with applications in many industries. Spent coffee grounds (SCGs) are a residue from the coffee industry that is rich in carbohydrates, having the potential to be valorized by this process. However, given the recalcitrant nature of this waste, the addition of a pretreatment step can significantly improve AF. In this work, several pretreatment strategies were applied to SCGs (acidic hydrolysis, basic hydrolysis, hydrothermal, microwave, ultrasounds, and supercritical CO2 extraction), evaluated in terms of sugar and inhibitors release, and used in AF. Despite the low yields of sugar extracted, almost all pretreatments increased SCOAs production. Milder extraction conditions also resulted in lower concentrations of inhibitory compounds and, consequently, in a higher concentration of SCOAs. The best results were obtained with acidic hydrolysis of 5%, leading to a production of 1.33 gSCOAs/L, an increase of 185% compared with untreated SCGs. [ABSTRACT FROM AUTHOR]

Large amounts of spent coffee grounds (SCGs) are produced annually worldwide. SCGs contain high levels of phenolics and other bioactive compounds that make them a potential source of reducing and stabilizing agents for the synthesis of metal nanoparticles. This study investigates the use of SCG extracts as a green strategy to produce silver nanoparticles (AgNPs). SCG extracts were obtained using aqueous ethanol as the solvent and then contacted with a silver nitrate solution under the selected conditions. A central composite design coupled with response surface methodology was used to evaluate the effects of solvent composition (C = 30–70% v/v), silver-to-phenolic ratio (R = 3–7 mol/mol), temperature (T = 25–55 °C) and pH (10–12) on the production of AgNPs. Characterization of AgNPs by DLS, TEM and XRD techniques showed that they were highly crystalline with a narrow size distribution. Under optimal reaction conditions, AgNPs with an average size of about 10 nm and a zeta potential of −30.5 to −20.7 mV were obtained. Overall, the results of this study indicate that SCGs are a promising material for the green synthesis of small-sized and stable AgNPs. [ABSTRACT FROM AUTHOR]

Coffee is considered to be one of the most renowned beverages and it is the second-most consumed product worldwide. Spent coffee grounds (SCGs) are the primary solid residue, which are generated during the coffee powder brewing in hot water or steam. The formation of huge amounts of these byproducts poses a severe threat to the environment, due to their organic nature and their high phenolic compounds concentration. Nevertheless, the latter are characterized as bioactive compounds with high antioxidant activity turning SCG into an economical raw matrix for the isolation of valuable components. Phenolic compounds that can be isolated from coffee byproducts can be potentially used as natural antioxidants in food, pharmaceutical, and cosmetics industries. Thus, the research community has focused its efforts on the optimization of phenolics extraction by the development of novel environmentally friendly techniques except for conventional maceration extraction using organic solvents. The objective of this review is to present an inclusive summary of the revalorization of SCGs and the potential uses of those solid residues through the recovery of phenolic compounds or the use of untreated or treated SCGs as biosorbents of valuable compounds from other food industry byproducts. [ABSTRACT FROM AUTHOR]

Coffee is one of the most popular beverages worldwide, whose production and consumption result in large amounts of waste, namely spent coffee grounds, constituting an important source of compounds for several industrial applications. This work focused on the establishment of the volatile fingerprint of five spent coffee grounds from different geographical origins using headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry (HS-SPME/GC-MS), as a strategy to identify volatile organic metabolites (VOMs) with potential application in the food industry as antioxidant, anti-inflammatory, and antiproliferative agents. One hundred eleven VOMs belonging to different chemical families were identified, of which 60 were found in all spent coffee grounds analyzed. Furanic compounds (34%), nitrogen compounds (30%), and esters (19%) contributed significant to the total volatile fingerprint. The data obtained suggest that spent coffee grounds have great potential to be used as raw material for different approaches in the food industry towards the development of new food ingredients or products for human consumption, in addition to pharmaceutical and cosmetic applications, namely as antioxidant (e.g., limonene, carvacrol), antimicrobial (e.g., pyrrole-2-carboxaldehyde, β-myrcene) and anti-inflammatory (e.g., furfural, 2-furanmethanol) agents, promoting their integral valorization within the circular bioeconomy concept. [ABSTRACT FROM AUTHOR]

The exploitation of massive amounts of food and agro-waste represents a severe social, economic, and environmental issue. Under the growing demand for food products that are free of toxic synthetic insecticides, a methanolic extract of spent coffee grounds (SCGs), which represent the main byproduct of coffee production, was applied in the current study as a bioinsecticide against the main pests of the green bean: Spodoptera littoralis, Agrotis ipsilon, Bemisia tabaci, Empoasca fabae, and Aphis craccivora. A deterrent assay, contact bioassay, and lethal concentration analysis were performed to reveal the repellent, antifeedant, and oviposition deterrent effects. Parallel to the above-mentioned bioassays, the phytochemical composition of the methanolic SCG extract was investigated via a high-performance liquid chromatography (HPLC) analysis. Fourteen phenolic acids and five flavonoids, in addition to caffeine (alkaloid), were identified in the extract. Cinnamic, rosmarinic, and gallic acids were the predominant phenolics, while apigenin-7-glucoside was the main flavonoid, followed by naringin, catechin, and epicatechin. The extract of SCGs showed an insecticidal effect, with a mortality between 27.5 and 76% compared to the control (7.4%) and based on the concentration of the extract used. In the same trend, the oviposition efficiency revealed different batches of laid eggs (0.67, 2.33, 7.33, and 8.67 batches/jar) for 100, 50, and 25% of the SCG extract and the control. Finally, the major components of the SCG extract were docked into the insecticide acetylcholinesterase enzyme to explore their potential for inhibition, where apigenin-7-glucoside showed a higher binding affinity, followed by catechin, compared to the control (lannate). The obtained findings could be a starting point for developing novel bioinsecticides from SCGs. [ABSTRACT FROM AUTHOR]

The continued and extensive use of synthetic herbicides to control weeds to maximize crop yield is no longer sustainable, as it results in negative impacts on the environment and human health. Innovative sustainable and resilient food production systems should preserve resources and environmental health by incorporating alternative natural herbicides, recycling waste, and favoring a circular economy. The present work assesses the value of different organic waste (Urtica dioica residues, Vicia faba pods, spent coffee grounds, and corn cobs) as bioherbicides and fertilizers in different seasons through pot and field two-year sequential experiments. Pot assays revealed that V. faba pods, spent coffee grounds, and corn cob waste showed the best inhibitory effect, which were subsequently evaluated in the Spring–Summer and Autumn crops. In the field, spent coffee grounds reduced the biomass of total naturally-emerged weeds and stimulated crop growth under scarce rainfall and warm days. However, its effect varied under different environmental conditions. Spent coffee grounds can partially control weeds in the field, which valorizes them as a bioherbicide and boosts sustainable agriculture. [ABSTRACT FROM AUTHOR]