Integration of chlorogenic acid recovery and bioethanol production from spent coffee grounds

Enhanced antioxidant capacity and yield of release of chlorogenic acids and derivates by solid-state fermentation of spent coffee ground under controlled conditions of aeration and moisturizing

This study proposed investigates the role of forced aeration flow and humidification pulses during solid-state fermentation (SSF) of spent coffee grounds (SCG) in optimizing fungal growth, metabolic activity, and bioactive compound release. Five fermentation conditions with aeration flows (0.5-1.5 L/min) and moisturizing pulses (30-90 mL/d) were evaluated. Chlorogenic acid (CGA), caffeic acid (CA), and quinic acid (QA) were quantified via HPLC, while antioxidant activities (AA) were assessed using ORAC, DPPH, and FRAP methods. The highest CGA yield (76.1 ± 5.2 mg/g SCGinitial) occurred between days 8-13 under 0.5LA-30LM conditions, while QA peaked at 89.5 ± 4.8 mg/g SCGinitial during days 27-30 under 0.5LA-90HM. AA reached 79,000 μmol TEAC/100 g SCGinitial at late fermentation stages. Low aeration and controlled moisture enhanced fungal colonization, enzymatic hydrolysis, and bioactive compound recovery. These findings evidence the potential of SSF for SCG valorization and offer a framework for process optimization in industrial applications.

The Impact of Thermal Treatment and In Vitro Digestion on Antioxidant Activity and Anti-Glycation Properties of Antioxidant Crude Extract From Hot and Cold Brew Spent Coffee Ground

The ethanoic extract of hot-brew spent-coffee ground (HSCG) and cold-brew spent-coffee ground (CSCG) were prepared with ultrasound-assisted extraction and subjected to thermal processes and in vitro digestion prior to analyze the inhibition ability of advanced glycation end products (AGEs) formation, a potential risk factor for Alzheimer's disease. The obtained HSCG and CSCG extracts contained mainly chlorogenic acid derivatives, according to liquid chromatography-mass spectrometer chromatogram. The glycation process was performed by using bovine serum albumin (BSA)/ glucose system with 3 weeks incubation. In the presence of HSCG and CSCG extracts at 250 μg/mL, after thermal treatment (pasteurization and sterilization) and in vitro digestion, the glycation process through the fructosamine, AGEs, and amyloid cross β structure formation was monitored, and these extracts exhibited an anti-glycation property at early and advanced stages after pasteurization and in vitro digestion compared to no thermal treatment. However, at high temperature of sterilization, the suppress of anti-glycation property had resulted and were related with the amount of antioxidant and the ability of antioxidant scavenging as presented in a dose manner. The calculated % caffeine bio-accessibility of HSGC extracts was 65.8%, 64.8%, and 52.4% in non-thermal, pasteurized, and sterilized samples while the higher bio-accessibility was found in CSCG sample as of 67.4, 66.6, and 63.1, respectively. A high correlation of TPC values, thermal treatments and in vitro digestions with the AGEs was detected. Polyphenols and caffeine content in these extracts were found to be responsible for the AGEs and amyloid cross β structure inhibition which might potentially reduce the risk of Alzheimer's disease.

HRMS Characterization and Antioxidant Evaluation of Costa Rican Spent Coffee Grounds as a Source of Bioactive Polyphenolic Extracts

Spent coffee grounds constitute a waste product that has attracted potential interest as a rich source of secondary metabolites such as polyphenolic compounds with antioxidant properties. In this work, aqueous extracts from samples of different spent coffee grounds from Costa Rica were prepared and analyzed using ultra-performance liquid chromatography coupled with high-resolution mass spectrometry using a quadrupole time-of-flight analyzer (UPLC-QTOF-ESI MS). This allowed for the identification of twenty-one compounds, including fourteen phenolic acids, three caffeoylquinic lactones, and four atractyligenin diterpenes. In addition, using UPLC coupled with a diode array detector (UPLC-DAD), we quantified the levels of caffeine (0.55-3.42 mg/g dry weight [DW]) and six caffeoylquinic and feruloylquinic acids (0.47-5.34 mg/g DW). The highest value was found for the fine-grind sample (EXP), both for phenolic acids and for total polyphenols (9.59 mg gallic acid equivalents [GAE]/g DW), compared to 2.13 and 1.70 mg GAE/g DW for the medium-grind (GR) and coarse-grind samples (PCR), respectively. The results obtained from the antioxidant evaluations using the 2,2-diphenyl-1-picrylhydrazyl assay (IC50 0.0964-6.005 g DW/L), the ferric-reducing antioxidant power (PFRAP) analysis (0.0215-0.1385 mmol FeSO4/g DW), the oxygen radical absorbance capacity (ORAC) assessment (45.7-309.7 μmol Trolox/g DW), and the Trolox equivalent antioxidant capacity (TEAC) assay (3.94-23.47 mg Trolox/g DW) also showed the best values for the fine-grind sample, with results similar to or higher than those reported in the literature. Statistical Pearson correlation analysis (p < 0.05) indicated a high correlation (R ≥ 0.842) between all antioxidant analyses, the total polyphenols, and the phenolic acid quantification using UPLC-DAD. These results show the potential for further studies aiming to exploit this waste product's bioactive properties, constituting the first detailed study of spent coffee grounds from Costa Rica.

Value-Added Products from Coffee Waste: A Review

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.

Sustainability issues along the coffee chain: From the field to the cup

The coffee industry is one of the most important commercial value chains worldwide. Nonetheless, it is also associated to several social, economic, and environmental concerns that impair its sustainability. The present review is focused on these main sustainability concerns from the field to the coffee cup, as well as on the strategies that are being developed and/or implemented to attain sustainability and circular economy principles in the different chain segments. In this context, distinct approaches have been applied, such as sustainable certifications (e.g., voluntary sustainability standards), corporate sustainability initiatives, direct trade, relationship coffee concepts, geographical indication, legislations, waste management, and byproducts valorization, among others. These strategies are addressed and discussed throughout this review, as well as their recognized advantages and limitations. Overall, there is still a long way to go to attain the much-desired sustainability in the coffee chain, being essential to join the efforts of all actors and entities directly or indirectly involved, namely, producers, retailers, roasters, governments, educational institutions (such as universities and scientific research institutes), and organizations.

The recovery from agro-industrial wastes provides different profiles of anti-inflammatory polyphenols for tailored applications

Food and agro-industrial processing produce a great amount of side-stream and waste materials that are excellent sources of functional bioactive molecules such as phenolic compounds that recover them can be beneficial not only for food sustainability but also to human for many industrial applications such as flavor compounds and therapeutic applications such as antimicrobial and anti-inflammatory. The treatments and extraction techniques have major effects on the recovery of bioactive compounds. Along with the conventional extraction methods, numerous innovative techniques have been evolved and have been optimized to facilitate bioactive extraction more efficiently and sustainably. In this work, we have summarized the state-of-the-art technological approaches concerning novel extraction methods applied for five most produced crops in Italy; Grape Pomace (GP), Tomato Pomace (TP), Olive Pomace (OP), Citrus Pomace (CP), and Spent Coffee Grounds (SCG), presenting the extraction yield and the main class of phenolic classes, with the focus on their biological activity as an anti-inflammatory in vitro and in vivo studies via describing their molecular mechanism of action.

Optimization of 5-CQA Extraction Conditions from Green Coffee By-Product (Coffea arabica) Using a Response-Surface Design and the Study of Its Extraction Kinetics

To take advantage of the residues generated in the production of products from green coffee and due to the special interest in the compounds contained in the bean, a by-product obtained after the extraction of the oil was studied. The physical characterization of the green-coffee-bean by-product was carried out. Subsequently, the extraction of compound 5-CQA was carried out via leaching using central composition design 24 and evaluating factors such as temperature, time, solid/solvent ratio, and ethanol percentage, and its yield was quantified using HPLC. In addition, the response-surface methodology was used to maximize the efficiency of 5-CQA extraction and to perform the kinetic study. Yields of 59 ± 2 mg of 5-CQA/g from the by-product were obtained, and by selecting the best leaching conditions, the kinetic study was performed at 45, 60, and 75 °C, increasing the yield to a total of 61.8 ± 3 mg of 5-CQA/g. By applying the kinetic model of mass transfer, a fit of R2 > 0.97 was obtained, with KLa values between 0.266 and 0.320 min−1. This study showed an approach to optimize the 5-CQA extraction conditions, resulting in a simple, fast, reproducible, accurate, and low-cost method.

Impact of a Pretreatment Step on the Acidogenic Fermentation of Spent Coffee Grounds

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.

Production and characterization of a new distilled beverage from green coffee seed residue

This study evaluated green coffee seed residue (GCSR) as an alternative substrate for producing distilled beverages. Two proportions of GCSR, 10% and 20% (w/v), were fermented and distilled in a copper alembic still. The spirits were characterized by GC-FID, HS-SPME GC-MS, and sensory analysis by trained panelists. Most of the 62 identified volatile compounds were affected by the GCSR concentration. Total terpenes, higher alcohols, and acetals showed the highest concentrations in the 10% GCSR spirit. Esters, acetates, and aldehydes were most abundant in the 20% GCSR. In the sensory analysis, the 10% GCSR spirit was characterized by floral, dairy, and almond aromas, while the 20% GCSR spirit was embodied coffee, vegetable, hazelnut, cooked cabbage, and nut descriptors. The results demonstrate the potential of GCSR as a substrate for producing coffee spirits with chemical and sensory qualities, with the 10% GCSR being the better option for fermentation.

Scientometric Overview of Coffee By-Products and Their Applications

As coffee consumption is on the rise, and the global coffee production creates an excess of 23 million tons of waste per year, a revolutionary transition towards a circular economy via the transformation and valorization of the main by-products from its cultivation and preparation (Coffee Husk (CH), Coffee Pulp (CP), Coffee Silverskin (CS), and Spent Coffee Grounds (SCG)) is inspiring researchers around the world. The recent growth of scholarly publications in the field and the emerging applications of coffee by-products published in these scientific papers encourages a systematic review to identify the knowledge structure, research hotspots, and to discuss the challenges and future directions. This paper displays a comprehensive scientometric analysis based on 108 articles with a high level of influence in the field of coffee by-products and their applications. According to our analysis, the research in this field shows an explosive growth since 2017, clustered in five core applications: bioactive compounds, microbial transformation, environmental applications, biofuels from thermochemical processes, and construction materials.

Polyphenol bioactivity evolution during the spontaneous fermentation of vegetal by-products

Food industry by-products such as grape pomace (GP), tomato pomace (TP), and spent coffee grounds (SCG) are rich in polyphenols (PP) but are easily biodegradable. The aim of this study is to test Spontaneous Fermentation (SF) as treatment to modify PP profile and bioactivity. The results highlighted that the by-products' organic matter and the microbial populations drove the SF evolution; heterolactic, alcoholic, and their mixtures were the predominant metabolisms of TP, GP, and SCG + GP co-fermentation. Increases in the extractable amounts and antiradical activity occurred for all the biomasses. Regarding the aglycate-PPs (APP), i.e. the most bioreactive PPs, significant changes occurred for TP and GP but did not influence the anti-inflammatory bioactivity. The co-fermentation increased significantly chlorogenic acid and consumed most of the APPs, acting as a purification system to obtain a highly concentrated APP fraction, so that the extract might be employed for a specific purpose.

Spent coffee ground as renewable energy source: Evaluation of the drying processes

Spent coffee ground (SCG) is an environmental nuisance material, but, if appropriately processed it can be converted into pellets, and thus, used as an energy source. The moisture content of the final product should be below 10%, to ensure safe storage, and elimination of microorganism growth (particularly moulds). The present study aims to identify the optimal drying process for removing moisture from SCG and to investigate changes to the composition of SCG due to drying, at temperatures around 75 °C, so that the dried SCG to qualify as renewable energy source. Three drying processes were employed for SCG drying (with initial moisture content of about 65%): oven drying, solar drying and open air sun drying, while SCG samples were placed in aluminium trays with thicknesses of 1.25, 2.5 and 4 cm. Based on the experimental results for SCG samples with thickness 2.5 cm, the open air sun drying process required 10 h to reach final moisture content of 37%, while solar drying achieved 10% moisture content in 10 h and oven drying achieved 7% moisture content in 6 h. The solar drying process proved as the most advantageous, due to low energy requirements and adequate quality of dried SCG. Also, experiments indicated that SCG storage at "normal room conditions" resulted to equilibrium moisture content in SCG of 8%, regardless of the initial moisture content. Furthermore, instrumental analyses of the SCG, revealed changes to its composition for a number of chemical groups, such as aldehydes, ketones, phytosterols, alkaloids, lactones, alcohols, phenols, pyrans and furans, among others. It was also identified that the SCG colour was affected due to the drying process.

Sustainable production of bio-based chemicals and polymers via integrated biomass refining and bioprocessing in a circular bioeconomy context

The sustainable production of bio-based chemicals and polymers is highly dependent on the development of viable biorefinery concepts using crude renewable resources for the production of diversified products. Within this concept, this critical review presents the availability of fractionated co-products and fermentable sugars that could be derived from major industrial and food supply chain side streams in EU countries. Fermentable sugars could be used for the production of bio-based chemicals and polymers. The implementation of biorefinery concepts in industry should depend on the evaluation of process efficiency and sustainability including techno-economic, environmental and social impact assessment following circular bioeconomy principles. Relevant sustainability indicators and End-of-Life scenarios have been presented. A case study on the techno-economic evaluation of bio-based succinic acid production from the organic fraction of municipal solid waste has been presented focusing on the evaluation of process profitability and feedstock requirements.

Production and characterization of a new distillate obtained from fermentation of wet processing coffee by-products

Coffee is one of the most important commodities worldwide. The industrial processing of coffee cherries generates a considerable volume of by-products such as wastewater, coffee pulp, mucilage, and husk. These by-products have sugars and nutrients that can be converted into value-added products via microbial action. In this study, for the first time, we evaluated the potential of coffee pulp and coffee wastewater as substrate for alcoholic fermentation produce a distilled beverage. The must composed by dry or wet coffee pulp and coffee wastewater added of commercial sucrose or sugarcane molasses was fermented by S. cerevisiae. After a screening step, a larger fermentation was carried out with the wet pulp added of sucrose due to its higher alcoholic fermentation efficiency. The distilled beverage contained 38% (v/v) ethanol and 0.2 g/L of acetic acid. The contaminants furfural, hydroxymethylfurfural and ethyl carbamate were below detection level. Among the 48 volatile compounds detected, the majority (21) were ethyl esters usually associated with floral and sweet aromas. Ethyl decanoate (996.88 µg/L) and ethyl dodecanoate (1088.09 µg/L) were the most abundant esters. Coffee spirit presented taste acceptance of 80% and sugarcane spirit, 70%. The tasters indicated an aroma acceptance of 86% for the coffee spirit and 78% for the sugarcane spirit. The results of this work demonstrate the potential for using coffee by-products to produce a good quality distilled beverage. Considering our results, especially sensorial analysis, we can infer that the produced coffee beverage represents a new alternative for adding value to the coffee production chain.

Biorefinery of spent coffee grounds waste: Viable pathway towards circular bioeconomy

The circular bioeconomy plan is an innovative research based scheme intended for augmenting the complete utilization and management of bio-based resources in a sustainable biorefinery route. Spent coffee grounds based biorefinery is the emerging aspect promoting circular bioeconomy. The sustainable circular bioeconomy by utilizing SCG is achieved by cascade approaches and the inclusion of many biorefinery approaches to obtain many bio-products. The maximum energy recovery can be obtained by process integration. The economic analysis of the biofuel production from SCG is dependent on the cost of raw material, transportation, the need of labor and energy, oil extraction operations and biofuel production. The inclusion of new products from already established product can minimize the investment cost when related to the production cost. A positive net present value can be achieved via SCG biorefinery which indicates the profitability of the process.

Energy Utilization of Spent Coffee Grounds in the Form of Pellets

Nowadays it is important to limit the use and combustion of fossil fuels such as oil and coal. There is a need to create environmentally acceptable projects that can reduce or even stop greenhouse gas emissions. In this article, we dealt with the objectives of energy policy with regard to environmental protection, waste utilization, and conservation of natural resources. The main objective of the research was to assess the possibility of the use of spent coffee grounds (SCG) as fuel. As a part of the solution, the processing of coffee waste in the form of pellets, analysis of calorific value and combustion in the boiler were proposed. The experiments were done with four samples of pellets. These samples were made from a mixture of wood sawdust and spent coffee grounds with ratio 30:70 (wood sawdust: spent coffee grounds), 40:60, 50:50 and 100% of spent coffee grounds. The calorific values were compared with wood sawdust pellets (17.15 MJ.kg−1) and the best lower calorific value of 21.08 MJ.kg−1 was measured for 100% of spent coffee grounds. This sample did not achieve the desired performance during the combustion in the boiler due to the low strength of the sample.

Bioconversion of biomass waste into high value chemicals

Dwindling petroleum resources and increasing environmental concerns have stimulated the production of platform chemicals via biochemical processes through the use of renewable carbon sources. Various types of biomass wastes, which are biodegradable and vastly underutilized, are generated worldwide in huge quantities. They contain diverse chemical constituents, which may serve as starting points for the manufacture of a wide range of valuable bio-derived platform chemicals, intermediates, or end products via different conversion pathways. The valorization of inexpensive, abundantly available, and renewable biomass waste could provide significant benefits in response to increasing fossil fuel demands and manufacturing costs, as well as emerging environmental concerns. This review explores the potential for the use of available biomass waste to produce important chemicals, such as monosaccharides, oligosaccharides, biofuels, bioactive molecules, nanocellulose, and lignin, with a focus on commercially viable technologies.

The Optimized Production of 5-(Hydroxymethyl)furfural and Related Products from Spent Coffee Grounds

The increasing consumption of coffee worldwide has led to higher amounts of spent coffee grounds (SCG) being produced which are generally disposed of in landfill or used as compost. However, the wide range of molecules present in SCG such as saccharides, lignin, lipids and proteins give this biomass source a large chemical functionality. In this work, SCG were fractionated to separate the components into three separate portions for further valorization; these were hemicellulose-enriched fractions (HEF), lignin-enriched fraction (LEF) and cellulose-enriched fraction (CEF). HEF was effectively used in the growth of the oleaginous yeast Metschnikowia pulcherrima, additionally, the C6 sugars present in this fraction suggests that it can be used in the production of 5-hydroxymethylfurfural (HMF). The LEF had a considerable high heating value (HHV) and would be suitable as a biofuel component for combustion. CEF was efficiently used in the production of HMF as 0.35 g of this product were obtained from 10 g of SCG. Such results demonstrate that SCG can be effectively used in the production of HMF within a biorefinery concept.

Converting environmental risks to benefits by using spent coffee grounds (SCG) as a valuable resource

Coffee is perhaps one of the most vital ingredients in humans' daily life in modern world. However, this causes the production of million tons of relevant wastes, i.e., plastic cups, aluminum capsules, coffee chaff (silver skin), and spent coffee grounds (SCG), all thrown untreated into landfills. It is estimated that 1 kg of instant coffee generates around 2 kg of wet SCG; a relatively unique organic waste stream, with little to no contamination, separated directly in the source by the coffee shops. The produced waste has been under researchers' microscope as a useful feedstock for a number of promising applications. SCG is considered a valuable, nutrients rich source of bioactive compounds (e.g., phenolics, flavonoids, carotenoids, lipids, chlorogenic and protocatechuic acid, melanoidins, diterpenes, xanthines, vitamin precursors, etc.) and a useful resource material in other processes (e.g., soil improver and compost, heavy metals absorbent, biochar, biodiesel, pellets, cosmetics, food, and deodorization products). This paper aims to provide a holistic approach for the SCG waste management, highlighting a series of processes and applications in environmental solutions, food industry, and agricultural sector. Thus, the latest developments and approaches of SCG waste management are reviewed and discussed.

Natural Phenol Polymers: Recent Advances in Food and Health Applications

Natural phenol polymers are widely represented in nature and include a variety of classes including tannins and lignins as the most prominent. Largely consumed foods are rich sources of phenol polymers, notably black foods traditionally used in East Asia, but other non-edible, easily accessible sources, e.g., seaweeds and wood, have been considered with increasing interest together with waste materials from agro-based industries, primarily grape pomace and other byproducts of fruit and coffee processing. Not in all cases were the main structural components of these materials identified because of their highly heterogeneous nature. The great beneficial effects of natural phenol-based polymers on human health and their potential in improving the quality of food were largely explored, and this review critically addresses the most interesting and innovative reports in the field of nutrition and biomedicine that have appeared in the last five years. Several in vivo human and animal trials supported the proposed use of these materials as food supplements and for amelioration of the health and production of livestock. Biocompatible and stable functional polymers prepared by peroxidase-catalyzed polymerization of natural phenols, as well as natural phenol polymers were exploited as conventional and green plastic additives in smart packaging and food-spoilage prevention applications. The potential of natural phenol polymers in regenerative biomedicine as additives of biomaterials to promote growth and differentiation of osteoblasts is also discussed.