Use of spent coffee grounds as food ingredient in bakery products

Coffee leaf valorisation into functional wheat flour rusk: their nutritional, physicochemical, and sensory properties

Coffee leaves are currently emerging as a promising agri-food resource rich in phenolics. This study aims to valorise coffee leaf powder (CLP) by incorporating it in refined wheat flour rusk formulations and analyse its physio-chemical, rheological, functional and sensory characteristics. The progressive replacement of CLP improved the dietary fibre (2.51 ± 0.2%), ash (1.09 ± 0.11%), and water absorption capacity (59.7 ± 0.1%) of the flours. It considerably enhanced the falling number and sedimentation values of the flour blends while decreased the loaf volume. Progressive increase in the dietary phenolics (232.21-435.19 mg/100 g), chlorogenic acid (6.0-7.5 mg/100 g), and ABTS antioxidant activity (963.89-1607.25 µMTEAC/g) of the rusks was observed upon CLP addition. Rusks with 3% CLP were found to have significantly acceptable physical and sensory characteristics. Thus, supplementation of CLP in rusk helps in valorising coffee leaves besides providing a functional bakery product to the coffee industry.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-024-05927-z.

The future in the litter bin - bioconversion of food waste as driver of a circular bioeconomy

Bioconversion of organic waste requires the development and application of rather simple, yet robust technologies capable of transferring biomass into energy and sustainable materials for the future. Food waste plays a significant role in this process as its valorisation reduces waste and at the same time avoids additional exploitation of primary resources. Nonetheless, to literally become "litterate". extensive research into such robust large-scale methods is required. Here, we highlight some promising avenues and materials which fulfill these "waste to value" requirements, from various types of food waste as sustainable sources for biogas, bioethanol and biodiesel to fertilizers and antioxidants from grape pomace, from old-fashioned fermentation to the magic of anaerobic digestion.

Utilization of spent coffee grounds as charring agent to prepare flame retardant poly(lactic acid) composites with improved toughness

The objective was to utilize spent coffee grounds (SCG) as charring agent to combine with ammonium polyphosphate (APP) to prepare flame retardant poly(lactic acid) (PLA) composites with improved toughness. PLA/APP-SCG and PLA/APP-SCG/KH560 composites were prepared, and silane coupling agent KH560 was applied to improve particle-matrix interfacial compatibility. The particle-matrix interface, char formation, flame retardancy, mechanical properties and fracture morphology of PLA composites were studied. Results showed that PLA/APP-SCG5% and PLA/APP-SCG20% passed UL-94 V-0 rating, and increase in charred residues was favorable for improving flame retardancy. Improved toughness was also obtained compared to PLA, attributed to debonding of APP from matrix under external force as well as plasticization effect of coffee oil contained in SCG. PLA/APP-SCG5%/KH560 and PLA/APP-SCG20%/KH560 showed smaller elongation at break and impact strength compared to PLA/APP-SCG5% and PLA/APP-SCG20%, respectively. The improved interfacial compatibility was unfavorable for debonding of APP from matrix, and both APP and SCG played the role of enhancing strength, thus decreasing toughness. PLA/APP-SCG/KH560 counterparts were actually set as parallel samples to prove that PLA/APP-SCG composites showed improved toughness with weak interfacial compatibility. This study has provided a practical approach to utilize bio-derived wastes as charring agent to prepare flame retardant PLA composites with enhanced toughness.

Research progress on generation, detection and inhibition of multiple hazards - acrylamide, 5-hydroxymethylfurfural, advanced glycation end products, methylimidazole - in baked goods

While baking produces attractive flavors for foods, it also generates various endogenous by-products, including acrylamide (AA), 5-hydroxymethylfurfural (5-HMF), advanced glycation end products (AGEs) and methylimidazole (MI). This review briefly presents the recent studies on the above hazards, and research progress on the formation and control of the above substances in detail. There have been more detailed studies on a single category of hazards. However, few studies and reports have considered the integrated prevention and control of multiple hazards, which is related to the difficulty of analyzing the reaction mechanisms of multiple hazards at multiple scales and under multiple phases in complex food matrices. In this regard, the sample pretreatment methods are a crucial step in achieving simultaneous detection. The coordinated implementation of various methods, including reducing precursor levels, modifying baking conditions and equipment, and incorporating exogenous additives, is necessary to achieve a synchronized reduction in multiple hazardous substances.

Coffee oligosaccharides and their role in health and wellness

Coffee oligosaccharides (COS) are novel sources of prebiotics comprising manno-oligosaccharides, galacto-oligosaccharides, arabinoxylan-oligosaccharides, and cello-oligosaccharides. These oligosaccharides function as prebiotics, antioxidant-dietary fiber owing to important physicochemical and physiological properties, adjuvants, pharma, nutraceutical food, gut health, immune system boosting, cancer treatment, and many more. Research suggests COS performs prebiotic action, as it enhances gut health by promoting beneficial bacteria in the colon and releasing functional metabolites such as SCFAs. However, research on COS concerning other metabolic illnesses is still lacking. Among various production strategies, pretreatment and enzymatic hydrolysis are preferred for the production of COS. Functional oligosaccharides can add value to coffee waste and reduce the environmental impact of coffee manufacturing, besides providing more options for healthy and active ingredients. This review updates COS, production, bio-activity, their role as a functional food, food supplements/natural food additives, prebiotics and many applications of health sectors. Research is desirable to extend information on COS and their bio-activity, besides in vivo and clinical trials, to assess their effects in prior human formulations into the food and therapeutic arena.

The Bioactive Substances in Spent Black Tea and Arabic Coffee Could Improve the Nutritional Value and Extend the Shelf Life of Sponge Cake after Fortification

The study aimed to evaluate the potential use of spent coffee powder (SCP) and spent tea powder (STP) as bioactive supplements for sponge cake. To achieve this aim, we initially compared the chemical properties of spent tea and coffee powders with those of their raw forms. Subsequently, three supplemented cake blends were prepared (1, 2, and 3% of SCP and STP) to test the effect of their addition on the chemophysical characteristics, sensory attributes, and shelf life of the final products. Our results indicated that spent tea and coffee are prospective materials for polyphenols. Spent tea powder could retain up to 72% (theaflavin trigallate), while spent coffee powder could retain up to 63.9% (1-caffeoylquinic acid) of the identified compounds compared to the raw materials. Furthermore, spent tea and coffee powders contained high levels of dietary fiber (18.95 and 31.65 g/100 g dry weight) and the elements potassium (254.6 and 1218.2 mg/100 g of DW), phosphorus (189.8 and 161.3 mg/100 g of DW), calcium (904.1 and 237.8 mg/100 g of DW), and magnesium (158.8 and 199.6 mg/100 g of DW). In addition, the fortified samples with SCP and STP significantly enhanced the nutritional values while retaining good sensory qualities compared to those of the control sample. Moreover, cakes fortified with the highest concentrations of SCP and STP (3%) showed a significant decrease in malondialdehyde content (MDA; 17.7 and 18.0 μg/g) and microbiological counts (2.4 and 2.5 log cfu/g) compared to the control cake after 14 days of storage. These findings suggest that incorporating SCP and STP into cakes not only enhances their nutritional value but also extends their shelf life. By utilizing these waste products, we can contribute to a more sustainable and ecofriendly food industry.

Spent Coffee Grounds and Novaluron Are Toxic to Aedes aegypti (Diptera: Culicidae) Larvae

Aedes aegypti (Diptera: Culicidae) is a vector for mosquito-borne diseases worldwide. Insecticide resistance is a major concern in controlling this mosquito. We investigated the chemical compounds in wet and dry spent coffee grounds (wSCGs and dSCGs) and evaluated the efficacy of dSCGs, wSCGs, and novaluron on the mortality and adult emergence inhibition of Ae. aegypti. We found higher concentrations of chemical compounds in wSCGs than in dSCGs. The wSCGs and dSCGs both contained total phenolic compounds, total flavonoid compounds, caffeic acid, coumaric acid, protocatechuic acid, and vanillic acid. Complete mortality was observed after 48 h of exposure to 50 g/L wSCGs, while similar mortality was found after 120 h of exposure to 10 µg/L of novaluron. The sublethal dose was a concentration of wSCGs (5 g/L) and novaluron (0.01, 0.1, and 1 µg/L) combined that resulted in a larval mortality lower than twenty percent (at 72 h) to determine their synergistic effects. The death rate of larvae exposed in sublethal combination of wSCGs and novaluron was significantly higher than that of its stand-alone. The findings indicate that the combination of wSCGs and novaluron at sublethal concentrations had synergistic effects on the mortality of Ae. aegypti larvae and could be applied as an alternative control measure.

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.

Conversion of Mixed Waste Food Substrates by Carotenogenic Yeasts of Rhodotorula sp. Genus

The consequence of the massive increase in population in recent years is the enormous production of mainly industrial waste. The effort to minimize these waste products is, therefore, no longer sufficient. Biotechnologists, therefore, started looking for ways to not only reuse these waste products, but also to valorise them. This work focuses on the biotechnological use and processing of waste oils/fats and waste glycerol by carotenogenic yeasts of the genus Rhodotorula and Sporidiobolus. The results of this work show that the selected yeast strains are able to process waste glycerol as well as some oils and fats in a circular economy model and, moreover, are resistant to potential antimicrobial compounds present in the medium. The best-growing strains, Rhodotorula toruloides CCY 062-002-004 and Rhodotorula kratochvilovae CCY 020-002-026, were selected for fed-batch cultivation in a laboratory bioreactor in a medium containing a mixture of coffee oil and waste glycerol. The results show that both strains were able to produce more than 18 g of biomass per litre of media with a high content of carotenoids (10.757 ± 1.007 mg/g of CDW in R. kratochvilovae and 10.514 ± 1.520 mg/g of CDW in R. toruloides, respectively). The overall results prove that combining different waste substrates is a promising option for producing yeast biomass enriched with carotenoids, lipids, and beta-glucans.

Coffee by-products: An underexplored source of prebiotic ingredients

Consumers' demand for foods with high nutritional value and health benefits has fueled the development of prebiotic foods. In coffee industry, cherries transformation into roasted beans generates a large amount of waste/by-products (pulp/husks, mucilage, parchment, defective beans, silverskin and spent coffee grounds) that usually end up in landfills. The possibility to use coffee by-products as relevant sources of prebiotic ingredients is herein ascertained. As a prelude to this discussion, an overview of pertinent literature on prebiotic action was conducted, including on biotransformation of prebiotics, gut microbiota, and metabolites. Existing research indicates that coffee by-products contain significant levels of dietary fiber and other components that can improve gut health by stimulating beneficial bacteria in the colon, making them excellent candidates for prebiotic ingredients. Oligosaccharides from coffee by-products have lower digestibility than inulin and can be fermented by gut microbiota into functional metabolites, such as short-chain fatty acids. Depending on the concentration, melanoidins and chlorogenic acids may also have prebiotic action. Nevertheless, there is still a lack of in vivo studies to validate such findings in vitro. This review shows how coffee by-products can be interesting for the development of functional foods, contributing to sustainability, circular economy, food security, and health.

The Potential of Spent Coffee Grounds in Functional Food Development

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.

Inhibitory effect of Ginkgo biloba seeds peptides on methylglyoxal-induced glycations

The aim of this study was to investigate the antiglycation activity and mechanism of two identified peptides, Valine-Valine-Phenylalanine-Proline-Glycine-Cysteine-Proline-Glutamic acid (VVFPGCPE) and Serine-Valine-Aspartic acid-Aspartic acid-Proline-Arginine-Threonine-Lysine (SVDDPRTL), from Ginkgo biloba seeds protein hydrolysates. Both VVFPGCPE and SVDDPRTL were efficient in bovine serum albumin (BSA)-methylglyoxal (MGO) model to inhibit BSA glycation, while VVFPGCPE showed higher antiglycation activity than SVDDPRTL. In antioxidant assays, VVFPGCPE scavenged more hydroxyl and super anion radicals, and chelated more Fe²⁺. Moreover, VVFPGCPE was more efficient in alleviating glycoxidation since it retained higher content of tryptophan and reduced dityrosine and kynurenine generation. Compared with SVDDPRTL, VVFPGCPE showed better performance in inhibiting protein aggregation and amyloid-like fibrillation formation. Therefore, VVFPGCPE was selected for further mechanism study. The circular dichroism analysis suggested VVFPGCPE could preserve α-helix structure and stabilize protein structure. The MGO trapping assay indicated VVFPGCPE (5 mg/mL) could capture 66.25% MGO within 24 h, and the mass spectrometry revealed VVFPGCPE could trap MGO by forming VVFPGCPE-mono-MGO adducts. Besides, molecular simulations suggested VVFPGCPE could interact with key glycation residues, arginine and lysine residues, of BSA mainly through van der Waals and hydrogen bonds. This study might supply a theoretical basis for the development of VVFPGCPE as an effective antiglycation agent.

Antioxidant Dietary Fiber Sourced from Agroindustrial Byproducts and Its Applications

Agroindustrial activities generate various residues or byproducts which are inefficiently utilized, impacting the environment and increasing production costs. These byproducts contain significant amounts of bioactive compounds, including dietary fiber with associated phenolic compounds, known as antioxidant dietary fiber (ADF). Phenolic compounds are related to the prevention of diseases related to oxidative stress, such as neurodegenerative and cardiovascular diseases. The mechanism of ADF depends on its chemical structure and the interactions between the dietary fiber and associated phenolic compounds. This work describes ADF, the main byproducts considered sources of ADF, its mechanisms of action, and its potential use in the formulation of foods destined for human consumption. ADF responds to the demand for low-cost, functional ingredients with great health benefits. A higher intake of antioxidant dietary fiber contributes to reducing the risk of diseases such as type II diabetes, colon cancer, obesity, and kidney stones, and has bile-acid retention-excretion, gastrointestinal laxative, hypoglycemic, hypocholesterolemic, prebiotic, and cardioprotective effects. ADF is a functional, sustainable, and profitable ingredient with different applications in agroindustry; its use can improve the technofunctional and nutritional properties of food, helping to close the cycle following the premise of the circular economy.

Jack Bean Development in Multimetal Contaminated Soil Amended with Coffee Waste-Derived Biochars

Coffee waste-derived biochar was found to immobilize heavy metals in contaminated soil, although there are few studies involving these materials. Given the large amount of waste generated in the coffee industry, this presents a relevant opportunity to contribute to the circular economy and environmental sustainability. Therefore, the objective of this study was to evaluate the effects of the application of biochars derived from coffee grounds and coffee parchment in the remediation of a Cd, Zn and Pb contaminated soil and at the development of jack beans (Canavalia ensiformis) in this area’s revegetation. The biochars were pyrolyzed at 700 °C, and the treatments were: contaminated soil (CT); contaminated soil + calcium carbonate (CaCO3); contaminated soil + 5% (weight (w)/weitght (w)) coffee ground biochar and contaminated soil + 5% (w/w) coffee parchment biochar. These treatments were incubated for 90 days, followed by the cultivation of jack beans for 60 days. Soil samples, soil solution and plants were analyzed for nutrients and heavy metals. The addition of coffee grounds and coffee parchment biochars significantly reduced the contents of heavy metals in the soil compared to the Control (32.13 and 42.95%, respectively, for Zn; 26.28 and 33.06%, respectively, for Cd and 28.63 and 29.67%, respectively, for Pb), all of which had a superior performance than the CaCO3 treatment. Thus, following the observed reduction in the soil soluble fraction of metals, its uptake by the plants was also reduced, especially limiting Cd and Pb accumulation in plant dry matter. In addition, coffee parchment biochar promoted a greater accumulation of nutrients in the shoots, i.e., for K and P (1450 and 21.5 mg pot−1, respectively, dry matter basis) compared to the control (54.4 and 9.3 mg pot−1, respectively). Therefore, coffee parchment biochar use in association with jack beans may represent a viable tool for the remediation of metal contamination concomitantly with revegetation of the contaminated area.

El procesamiento del grano de café. Del tueste a la infusión

El café es una de las bebidas más consumidas en el mundo y su popularidad no está basada en su valor nutricional o sus potenciales beneficios a la salud, si no en su sabor placentero y las propiedades estimulantes de la cafeína. Esto es respaldado por las últimas estadísticas publicadas por la Organización Internacional del Café (ICO, por sus siglas en inglés) según la cual aproximadamente 1.4 billones de tazas de café son consumidas diariamente además del hecho de que la taza de consumo global se ha duplicado en los últimos 50 años por causa de la apertura de nuevos mercados. La amplia aceptación del café está ligada a sus propiedades sensoriales las cuales a su vez están fuertemente influenciadas por una cadena de eventos que inician desde la cosecha y las practicas postcosecha (i.e., fermentación, lavado, secado, tamizado, eliminación de granos defectuosos y almacenamiento), seguidas por el tueste, molido y empacado del producto para su posterior comercialización. No obstante, existen otros factores que también afectan las propiedades organolépticas de la bebida tales como, pero no limitado a: el pH y temperatura del agua, las mezclas realizadas antes o después del tueste, la especie y/o variedad de café, las adulteraciones, la incorporación de aditivos, el método de preparación de la bebida, el tipo de recipiente en el que se sirve la infusión, entre otros. El presente artículo presenta una breve descripción de los factores que afectan la calidad de la taza relacionados con el procesamiento del grano oro del café. Sin embargo, aunque los factores ya mencionados son tomados en consideración por los catadores, para fines comerciales, la calidad del café está y siempre estará en manos del consumidor. Después de todo la mejor prueba es cuando la persona lo prueba. Palabras clave: organoléptica, perfil de tueste, endotérmica, exotérmico, ma-croscópica, microscópica, reacción Maillard, caramelización.

Towards the sustainable and circular bioeconomy: Insights on spent coffee grounds valorization

Discovered in Ethiopia, coffee became a popular beverage in Asia, Europe, Latin America, Australia, Africa and the North America as a drink after water and the largest goods after petroleum. However, the coffee industry generates a huge biomass as its byproducts of which the spent coffee grounds (SCG) is concerning, especially in the production chain away from the farm. Therefore, the valorization and revalorization of the SCG has a huge impact on the socioeconomic and environmental sustainability of the industry, up to the realization of the circular bioeconomy. With the advancing biorefinery concept, even an almost complete recovery of the SCG is reported at an experimental level. Such kind of studies increased with time following the action of the Sustainable Development Goals by the United Nations Development Program promulgated in 2015. The current review highlights on the background, socioeconomic, environmental contexts of coffee production and the SCG valorization and revalorization studies. Refereeing to 154 screened articles published in over 30 years' time, the SCG revalorization efforts and its integrated biorefinery as a green management approach are uniquely addressed. Plenty of studies have reported the production of bio-products from the SCG, such as the derivation of adsorbents, biochar, bioethanol, biogas, biodiesel, bio-oil, compost, construction material aggregates, cosmetics, electricity and food ingredients. In conclusion, the recovery potential of the SCG is promising and can substantially contribute to a sustainable and green bioeconomy. Nevertheless, the recovery of bioactive materials through SCG fermentation is still lacking. Most studies are conducted on a lab scale, which needs to be piloted and commissioned. Furthermore, the link between climate change and variability vis-à-vis the sustainable management of the SCG remains unaddressed.

Influence of Neonatal Sex on Breast Milk Protein and Antioxidant Content in Spanish Women in the First Month of Lactation

Breast milk (BM) is the best food for newborns. Male sex is associated with a higher risk of fetal programming, prematurity, and adverse postnatal outcome, being that BM is an important health determinant. BM composition is dynamic and modified by several factors, including lactation period, prematurity, maternal nutritional status, and others. This study was designed to evaluate the influence of sex on BM composition during the first month of lactation, focused on macronutrients and antioxidants. Forty-eight breastfeeding women and their fifty-five newborns were recruited at the Hospital Clínico San Carlos (Madrid, Spain). Clinical sociodemographic data and anthropometric parameters were collected. BM samples were obtained at days 7, 14, and 28 of lactation to assess fat (Mojonnier method), protein (Bradford method), and biomarkers of oxidative status: total antioxidant capacity (ABTS and FRAP methods), thiol groups, reduced glutathione, superoxide dismutase and catalase activities, lipid peroxidation, and protein oxidation (spectrophotometric methods). Linear mixed models with random effects adjusted by maternal anthropometry, neonatal Z-scores at birth, and gestational age were used to assess the main effects of sex, lactation period, and their interaction. BM from mothers with male neonates exhibited significantly higher protein, ABTS, FRAP, and GSH levels, while catalase showed the opposite trend. No differences between sexes were observed in SOD, total thiols, and oxidative damage biomarkers. Most changes were observed on day 7 of lactation. Adjusted models demonstrated a significant association between male sex and proteins (β = 2.70 ± 1.20; p-Value = 0.048). In addition, total antioxidant capacity by ABTS (β = 0.11 ± 0.06) and GSH (β = 1.82 ± 0.94) showed a positive trend near significance (p-Value = 0.056; p-Value = 0.064, respectively). In conclusion, transitional milk showed sex differences in composition with higher protein and GSH levels in males. This may represent an advantage in the immediate perinatal period, which may help to counteract the worse adaptation of males to adverse intrauterine environments and prematurity.

Potential Uses of Spent Coffee Grounds in the Food Industry

Current estimates place the amount of spent coffee grounds annually generated worldwide in the 6 million ton figure, with the sources of spent coffee grounds being classified as domestic (i.e., household), commercial (i.e., coffee houses, cafeterias and restaurants), and industrial (i.e., soluble and instant coffee industries). The majority of the produced spent coffee grounds are currently being inappropriately destined for landfills or to a form of energy recovery (e.g., incineration) as a refuse-derived fuel. The disposal of spent coffee in landfills allows for its anaerobic degradation with consequent generation and emission of aggressive greenhouse gases such as methane and CO₂, and energy recovery processes must be considered an end-of-life stage in the lifecycle of spent coffee grounds, as a way of delaying CO₂ emissions and of avoiding emissions of toxic organic volatile compounds generated during combustion of this type of waste. Aside from these environmental issues, an aspect that should be considered is the inappropriate disposal of a product (SCG) that presents unique thermo-mechanical properties and textural characteristics and that is rich in a diversity of classes of compounds, such as polysaccharides, proteins, phenolics, lipids and alkaloids, which could be recovered and used in a diversity of applications, including food-related ones. Therefore, researchers worldwide are invested in studying a variety of possible applications for spent coffee grounds and products thereof, including (but not limited to) biofuels, catalysts, cosmetics, composite materials, feed and food ingredients. Hence, the aim of this essay was to present a comprehensive review of the recent literature on the proposals for utilization of spent coffee grounds in food-related applications, with focus on chemical composition of spent coffee, recovery of bioactive compounds, use as food ingredients and as components in the manufacture of composite materials that can be used in food applications, such as packaging.

A Review of Recent Advances in Spent Coffee Grounds Upcycle Technologies and Practices

Coffee is the world’s second largest beverage only next to water. After coffee consumption, spent coffee grounds (SCGs) are usually thrown away and eventually end up in landfills. In recent years, technologies and policies are actively under development to change this century old practice, and develop SCGs into value added energy and materials. In this paper, technologies and practices are classified into two categories, those reuses SCGs entirely, and those breakdown SCGs and reuse by components. This article provided a brief review of various ways to reuse SCGs published after 2017, and provided more information on SCG quantity, SCG biochar development for pollutant removal and using SCG upcycle cases for education. SCG upcycle efforts align the best with the UN Sustainable Development Goals (SDG) #12 “ensure sustainable consumption and production patterns,” the resultant fuel products contribute to SDG #7 “affordable and clean energy,” and the resultant biochar products contribute to SDG #6, “clean water and sanitation.”

The wastes of coffee bean processing for utilization in food: a review

A few million cubic tons of waste are generated annually as a result of coffee processing. As a beverage, coffee in itself is a rich source of melanoidins, phenolic compounds, and other phytonutrients which confer a wide range of health benefits. These wastes generated every year are usually discarded as landfill mass, mixed with animal fodder, or incinerated. Coffee wastes, due to their high content of tannins and caffeine, can degrade the soil quality and induce carcinogenicity when mixed with animal fodder. This review aims to identify the potential of coffee silver skin and spent coffee grounds, both generated as a result of the roasting process and instantization processes. Coffee husk and coffee flour are also well-known for their excellent bioactive roles. The proximate composition of coffee silverskin indicates a rich dietary fibre source and finds wide applications in bakery and other allied food products. This process could generate a value-added product and alleviate the disposing quality of remnant spent coffee grounds. Companies are exploring novel ideas of producing coffee flour obtained from drying and milling of coffee cherries for applications in day-to-day food products. Coffee and coffee waste combined with its high concentration of fibre, colorant pigments, and antioxidant compounds, has immense potential as a functional ingredient in food systems and needs to be explored further for its better utilization.

Influences of spent coffee grounds on skin mucosal and serum immunities, disease resistance, and growth rate of Nile tilapia (Oreochromis niloticus) reared under biofloc system

The study was executed to find out the potential effects spent coffee ground (SCG) on Nile tilapia's skin mucosal and serum immunities, disease prevention, and growth rate reared in a biofloc system. Nile tilapia fingerlings (average weight 15.25 ± 0.07 g) were disseminated into 15 aquaria (150 L tank^-1) at a density of 20 fish per aquarium and treated five diets: SCG1 (control), SCG2 (10 g kg^-1), SCG3 (20 g kg^-1), SCG4 (40 g kg^-1), and SCG5 (80 g kg^-1) for eight weeks. A Completely Randomized Design (CRD) with three replications was applied. Growth rate, skin mucus, and serum immunities were quantified every 4 weeks; whereas the challenge study was conducted at the termination of the feeding trial. The outputs indicated that dietary incorporation of SCG give rise to the enhancement of SGR and FCR in comparison with the control, with best levels noted in fish fed SCG2 diet. Similarly, significant enhancements in skin mucosal and serum immunities were revealed in fish treated SCG2 over the control and other SCG diets. Likewise, higher survival rates against Streptococcus agalactiae were displayed in fish fed SCG, with the maximum level displayed in the fish treated SCG2. In conclusion, dietary supplementation of SCG2 (10 g kg^-1) can be potential used as immunostimulants in tilapia aquaculture.

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.

Sensory Characteristics of Two Kinds of Alcoholic Beverages Produced with Spent Coffee Grounds Extract Based on Electronic Senses and HS-SPME-GC-MS Analyses

In this work, the hydrothermal extract of spent coffee grounds (SCG) was used to make alcoholic beverages with commercial S. cerevisiae strain D254. The sensory characteristics of the SCG alcoholic beverages were analyzed using sensory description, electronic nose, electronic tongue, and gas chromatography-mass spectrometry (GC-MS). The results suggested that the supplement of 0.20% (NH4)2HPO4 was effective at improving growth and alcohol fermentation of Saccharomyces cerevisiae D254 in SCG extract. SCG fermented beverages (SFB) and SCG distilled spirits (SDS) produced at the optimized fermentation conditions had appropriate physicochemical properties and different sensory characteristics. Fermentation aromas, especially esters, were produced in SFB, increasing the complexity of aroma and lowing the irritating aroma. The combination of original and fermentation components might balance the outstanding sourness, astringency, and saltiness tastes of SFB. The fermentation aroma was partially lost and the sourness, bitterness, astringency, and saltiness tastes were relieved in distillation, leading to the relatively more prominent aroma typicality of coffee and a soft taste. These findings lay a foundation for producing new high-quality coffee-flavored alcoholic beverages or flavoring liquors.

Interest of Coffee Melanoidins as Sustainable Healthier Food Ingredients

Coffee melanoidins are generated by the Maillard reaction during the thermal processes occurring in the journey of coffee from the plant to the cup (during drying and roasting). Melanoidins, the brown pigments formed as the end products of this reaction, have been reported in cascara, silverskin, spent coffee grounds, and coffee brew. The latter is one of the main natural sources of melanoidins of the daily diet worldwide. However, their presence in coffee by-products has been recently described. These complex macromolecules possess multiple health-promoting properties, such as antioxidant, anti-inflammatory, dietary fiber effect, and prebiotic capacity, which make them very interesting from a nutritional point of view. In addition, they have a great impact on the sensory profile of foods and their acceptance by the consumers. The present study is a descriptive, narrative, mini-review about the nature, structure, digestibility, properties (sensory, nutritional, and health-promoting), safety and regulatory status of melanoidins from the coffee brew and its by-products with a special emphasis on the latter.

Preparation and characterization of soybean insoluble dietary fiber and its prebiotic effect on dyslipidemia and hepatic steatosis in high fat-fed C57BL/6J mice

The potential benefits of insoluble dietary fiber (IDF) in the regulation of lipid metabolism have been reported in large prospective cohort studies although the molecular regulatory mechanism is still unclear. Okara is a by-product obtained during soybean processing for soy milk and soybean curd (tofu), which is rarely utilized and can be a cheap potential dietary fiber (DF) resource. In this study, the structure and physicochemical properties of insoluble dietary fiber (SIDF) extracted from okara were characterized, and the prebiotic effects on fat metabolism were investigated in vivo. The results showed that the main monosaccharides of SIDF (90.50%) identified were galactose, arabinose, xylose, rhamnose and glucose. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD) analyses suggested that SIDF had a loose and porous structure, polysaccharide functional groups, and a typical crystalline cellulose I structure. In addition, SIDF had ideal oil-adsorption capacity (OAC; 7.95 g g-1) and significantly improved cholesterol adsorption (11.14 mg g-1) at pH 7.0. In vivo, IDF supplementation reduced the serum lipid levels and inhibited hepatic fat accumulation. Additionally, SIDF administration improved hepatic steatosis by stimulating lipolysis via upregulation of PPARα, CYP4a10 and CPT1a. This is the first systematic study on the composition, structure, physicochemical properties, adsorption function and biological effects of SIDF. The above results show that SIDF could be used as an ideal functional ingredient in food processing as well as play a positive role in improving the added value of okara and promoting its comprehensive utilization.

Production of Enriched Sporidiobolus sp. Yeast Biomass Cultivated on Mixed Coffee Hydrolyzate and Fat/Oil Waste Materials

One of the most addressed topics today is the transfer from a linear model of economics to a model of circular economics. It is a discipline that seeks to eliminate waste produced by various industries. The food industry generates huge amounts of waste worldwide, particularly the coffee industry, and related industries produce millions of tons of waste a year. These wastes have potential utility in biotechnology, and in the production of energy, fuels, fertilizers and nutrients, using green techniques such as anaerobic digestion, co-digestion, composting, enzymatic action, and ultrasonic and hydrothermal carbonization. This work is focused on the biotechnological use of processed spent coffee grounds (SCG) and waste fat/oil materials by some Sporidiobolus sp. carotenogenic yeasts in the model of circular economics. The results show that selected yeast strains are able to grow on SCG hydrolysate and are resistant to antimicrobial compounds present in media. The most productive strain Sporidiobolus pararoseus CCY19-9-6 was chosen for bioreactor cultivation in media with a mixture of coffee lignocellulose fraction and some fat wastes. Sporidiobolus pararoseus CCY19-9-6 was able to produce more than 22 g/L of biomass in mixture of SCG hydrolysate and both coffee oil and frying oil. The combined waste substrates induced the production of lipidic metabolites, whereby the production of carotenoids exceeded 5 mg/g of dry biomass. On media with coffee oil, this strain produced high amounts of ubiquinone (8.265 ± 1.648 mg/g) and ergosterol (13.485 ± 1.275 mg/g). Overall, the results prove that a combination of waste substrates is a promising option for the production of carotenoid- and lipid-enriched yeast biomass.

In Vitro Bioaccessibility and Antioxidant Activity of Polyphenolic Compounds from Spent Coffee Grounds-Enriched Cookies

Spent coffee ground (SCG) is a significant by-product generated by the coffee industry. It is considered a great source of bioactive molecules well-recognized for exerting biological properties. This study aimed to implement SCG in a baked foods, such as cookies (SCGc), to increase their bioactive potential. A comprehensive study of the polyphenolic fraction of the SCG and SCGc using a high-resolution mass spectrometry analysis was performed. Moreover, the polyphenol bioaccessibility and change in antioxidant activity during simulated gastrointestinal digestion (GiD) were assessed. Data showed that SCGc provided 780 mg of melanoidins, 16.2 mg of chlorogenic acid (CGA), 6.5 mg of caffeine, and 0.08 mg of phenolic acids per 100 g of sample. Moreover, the 5-caffeoylquinic acid was the most relevant CGA found in SCG (116.4 mg/100 g) and SCGc (8.2 mg/100 g) samples. The antioxidant activity evaluated through three spectrophotometric tests, and the total phenolic compounds of SCGc samples exhibited significantly higher values than the control samples. Furthermore, during simulated GiD, the highest bioaccessibility of SCGc polyphenols was observed after the colonic stage, suggesting their potential advantages for human health. Therefore, SCG with high content in bioactive molecules could represent an innovative ingredient intended to fortify baked food formulations.

Spent Coffee Grounds’ Valorization towards the Recovery of Caffeine and Chlorogenic Acid: A Response Surface Methodology Approach

The amount of spent coffee grounds (SCGs) created, represents an environmental challenge worldwide. In this context, the aim of the present study was to exploit the potential of SCGs as a source of bioactive compounds that can be utilized in high value-added products. Thus, a cost-effective and environmentally friendly extraction technique was developed to ensure extracts with high total phenolic content and antioxidant activity, as well as significant amounts of caffeine and chlorogenic acid. Response surface methodology was implemented to evaluate the effects of the main extraction parameters (i.e., time, temperature, and ethanol-to-water ratio) and their interactions on the defined responses. The ethanol ratio was found to be the most significant variable. Then, a set of optimum values was determined (i.e., 7 min, 75 °C, and ethanol:water ratio 5:95), where the predicted values for responses were found to be 5.65% for the yield (Y1), 152.68 mg gallic acid equivalents per L for total phenolic content (Y2), 0.797 μmol Trolox equivalent per mL for the antioxidant activity (Y3), 30.5 ppm for caffeine concentration (Y4), and 17.4 ppm for chlorogenic acid concentration (Y5). Furthermore, the corresponding high experimental values from the validation experiment fitted well to these predictions, clearly clarifying the high potential of SCG extracts for use in high value-added applications.

Potential applications of by-products from the coffee industry in polymer technology - Current state and perspectives

Coffee is one of the most popular beverages in the world, and its popularity is continuously growing, which can be expressed by almost doubling production over the last three decades. Cultivation, processing, roasting, and brewing coffee are known for many years. These processes generate significant amounts of by-products since coffee bean stands for around 50% of the coffee cherry. Therefore, considering the current pro-ecological trends, it is essential to develop the utilization methods for the other 50% of the coffee cherry. Among the possibilities, much attention is drawn to polymer chemistry and technology. This industry branch may efficiently consume different types of lignocellulosic materials to use them as fillers for polymer composites or as intermediate sources of particular chemical compounds. Moreover, due to their chemical composition, coffee industry by-products may be used as additives modifying the oxidation resistance, antimicrobial, or antifungal properties of polymeric materials. These issues should be considered especially important in the case of biodegradable polymers, whose popularity is growing over the last years. This paper summarizes the literature reports related to the generation and composition of the coffee industry by-products, as well as the attempts of their incorporation into polymer technology. Moreover, potential directions of research based on the possibilities offered by the coffee industry by-products are presented.

From brown to colored: Polylactic acid composite with micro/nano-structured white spent coffee grounds for three-dimensional printing

Functional fillers in three-dimensional (3D) printing composite filaments offer an innovative way spent coffee grounds (SCGs) can be reused. However, the inherent brownness of SCGs places a limit on the color in which the composite filament and, consequently, the finished print appears. Herein, colored composite filaments for fused deposition modeling were successfully fabricated, where micro/nano-structured decolorized SCGs (MN-DSCGs) were embedded within polylactic acid (PLA) matrix. At the optimum condition, the 3D prints using composite filaments exhibit comparable tensile and flexural strength to the PLA counterparts. Also, they demonstrate superior melt flow and excellent print quality. Under the same condition, 3D printed MN-DSCGs/PLA blend has sufficient color restoration as compared to the prints using virgin PLA.

Solid Fuel Characteristics of Pellets Comprising Spent Coffee Grounds and Wood Powder

To help mitigate the effects of global warming and fossil fuel depletion caused by human use of fossil fuels, solid fuel pellets were developed from a mixture of spent coffee grounds (SCG) and pine sawdust (PS). The feasibility of SCG-PS pellets as biofuel was also verified by evaluating its fuel quality. An increase in the proportion of SCG in the pellet led to an increase in its calorific value, owing to the high C, H, and oil contents, and increases in the ash and S contents, owing to the high S content in SCG. Analysis of the feedstock particle size distribution revealed that SCG particles are smaller than PS particles; thus, the durability of the pellet decreases as the proportion of SCG increases. Accordingly, the samples with higher SCG proportions (70 and 90 wt.%) did not meet the moisture content standards for biomass solid refuse fuel (bio-SRF) set by the Korea Ministry of Environment, whereas the samples with lower SCG proportions did. In particular, CP10 (10 wt.% SCG + 90 wt.% PS) satisfied the quality standards of Grade 1 wood pellets, demonstrating the feasibility of using SCG as a raw material for biofuel pellet production.

Green Extracts from Coffee Pulp and Their Application in the Development of Innovative Brews

Coffee pulp, a by-product of coffee production, contains valuable compounds such as caffeine and chlorogenic acid with high antiradical activity. In this study, aqueous solutions of β-cyclodextrin (β-CD) were used as a non-conventional solvent for the extraction of targeted compounds from coffee pulp. The parameters of β-CD concentration (Cβcd), liquid-to-solid ratio (L/S), and temperature (T) were evaluated based on the antiradical activity (AAR) and the caffeine content (CCaf). The optimum operational conditions were found to be Cβcd: 9.25 mg/mL, L/S: 30 mL/g and T: 80 °C. The sensory profiles of brews prepared with coffee and coffee pulp with or without cyclodextrin were studied with quantitative descriptive analysis. The brew from the by-product had fruity, botanic, sweet and sourness sensory properties, and cyclodextrin was found to be able to affect the overall taste of the brew.

A review on valorization of spent coffee grounds (SCG) towards biopolymers and biocatalysts production

Spent coffee grounds (SCG) are an important waste product millions of tons generated from coffee consumption and could be effectively utilized for various applications due to their high organic content. SCG can be used as a potential feedstock to develop coffee-based biorefinery towards value-added products generation through various biotechnological processes. Considerable developments have been reported on emerging SCG-based processes/products in various environmental fields such as removal of heavy metals and cationic dyes and in wastewater treatment. In addition, SCG are also utilized to produce biochar and biofuels. This review addressed the details of innovative processes used to produce polymers and catalysts from SCG. Moreover, the application of these developed products is provided and future directions of the circular economy for SCG utilization.

Influence of Maternal Age and Gestational Age on Breast Milk Antioxidants During the First Month of Lactation

Breast milk (BM) is beneficial due to its content in a wide range of different antioxidants, particularly relevant for preterm infants, who are at higher risk of oxidative stress. We hypothesize that BM antioxidants are adapted to gestational age and are negatively influenced by maternal age. Fifty breastfeeding women from two hospitals (Madrid, Spain) provided BM samples at days 7, 14 and 28 of lactation to assess total antioxidant capacity (ABTS), thiol groups, reduced glutathione (GSH), superoxide dismutase (SOD) and catalase activities, lipid peroxidation (malondialdehyde, MDA + 4-Hydroxy-Trans-2-Nonenal, HNE), protein oxidation (carbonyl groups) (spectrophotometry) and melatonin (ELISA). Mixed random-effects linear regression models were used to study the influence of maternal and gestational ages on BM antioxidants, adjusted by days of lactation. Regression models evidenced a negative association between maternal age and BM melatonin levels (β = -7.4 ± 2.5; p-value = 0.005); and a negative association between gestational age and BM total antioxidant capacity (β = -0.008 ± 0.003; p-value = 0.006), SOD activity (β = -0.002 ± 0.001; p-value = 0.043) and protein oxidation (β = -0.22 ± 0.07; p-value = 0.001). In conclusion, BM antioxidants are adapted to gestational age providing higher levels to infants with lower degree of maturation; maternal ageing has a negative influence on melatonin, a key antioxidant hormone.

Applications of Compounds from Coffee Processing By-Products

To obtain the coffee beverage, approximately 90% of the edible parts of the coffee cherry are discarded as agricultural waste or by-products (cascara or husk, parchment, mucilage, silverskin and spent coffee grounds). These by-products are a potential source of nutrients and non-nutrient health-promoting compounds, which can be used as a whole ingredient or as an enriched extract of a specific compound. The chemical composition of by-products also determines food safety of the novel ingredients. To ensure the food safety of coffee by-products to be used as novel ingredients for the general consumer population, pesticides, mycotoxins, acrylamide and gluten must be analyzed. According with the priorities proposed by the Food Agriculture Organization of the United Nations (FAO) to maximize the benefit for the environment, society and economy, food waste generation should be avoided in the first place. In this context, the valorization of food waste can be carried out through an integrated bio-refinery approach to produce nutrients and bioactive molecules for pharmaceutical, cosmetic, food and non-food applications. The present research is an updated literature review of the definition of coffee by-products, their composition, safety and those food applications which have been proposed or made commercially available to date based on their chemical composition.

Lipid profile and growth of black soldier flies (Hermetia illucens, Stratiomyidae) reared on by-products from different food chains

BACKGROUND

The total amount of bio-waste produced annually in the EU by the food and beverage chains is estimated at 37 billion kg. The use of insects for the valorization of by-products from these value chains may represent a sustainable solution. This study aimed to investigate the by-products obtained from different food chains and used for the rearing of black soldier fly (BSF) prepupae, and to evaluate the content and profile of the lipid extracted from the prepupae and outline its possible applications. The substrates used in this experiment were: (i) industrial by-products (brewery spent grains, cows' milk whey, grape stalks, and tomato peels and seeds) and (ii) by-products from retailers (bread dough, fish scraps, and spent coffee ground). Fat extracted from prepupae using an adjusted Folch method was used for total lipid content and fatty acid profile.

RESULTS

The best larval performances were obtained from beer (0.22 g_weight per prepupa), tomato (0.19 g_weight per prepupa), and cheese (0.14 g_weight per prepupa) food-chain by-products. The extremely different compositions of the substrates were reflected in the differentiated lipid profile of the BSF prepupae and in the range of ratios between unsaturated and saturated fatty acids, which varied from 0.37 for cows' milk whey to 1.34 for tomato peels and seeds.

CONCLUSION

The lipids, proteins, and chitin extracted from prepupae are high-value bio-based products that could be used in the feed / food industry or for the development of innovative biomaterials, such as biodiesel. These results suggest that food-chain by-products are the best candidates for insect-bioconversion purposes. © 2020 Society of Chemical Industry.