Assessment of total (free and bound) phenolic compounds in spent coffee extracts

Spent coffee is the main byproduct of the brewing process and a potential source of bioactive compounds, mainly phenolic acids easily extracted with water. Free and bound caffeoylquinic (3-CQA, 4-CQA, 5-CQA), dicaffeoylquinic (3,4-diCQA, 3,5-diCQA, 4,5-diCQA), caffeic, ferulic, p-coumaric, sinapic, and 4-hydroxybenzoic acids were measured by HPLC, after the application of three treatments (alkaline, acid, saline) to spent coffee extracts. Around 2-fold higher content of total phenolics has been estimated in comparison to free compounds. Phenolic compounds with one or more caffeic acid molecules were approximately 54% linked to macromolecules such as melanoidins, mainly by noncovalent interactions (up to 81% of bound phenolic compounds). The rest of the quantitated phenolic acids were mainly attached to other structures by covalent bonds (62-97% of total bound compounds). Alkaline hydrolysis and saline treatment were suitable to estimate total bound and ionically bound phenolic acids, respectively, whereas acid hydrolysis is an inadequate method to quantitate coffee phenolic acids

Influence of extraction process on antioxidant capacity of spent coffee

Spent coffee that is produced in tons by restaurants and cafeterias, and consumers at domestic levels, could be a good opportunity to have an important source of natural antioxidants. The main aim of this work was to study the influence of several process factors on the antioxidant capacity extraction from spent coffee. Total phenolic compounds, radical scavenging activity (ABTS and DPPH) and browned compounds (Abs 420 nm) of spent coffee extracts obtained with continuous (Soxhlet 1 h and 3 h) and discontinuous methods (solid-liquid extraction and filter coffeemaker), several solvents (water, ethanol, methanol and their mixtures), successive extractions, and water with different pHs (4.5, 7.0 and 9.5) were carried out. Spent coffee extracts with the highest antioxidant capacity were obtained after one extraction with neutral water (pH 7.0) in a filter coffeemaker (24 g spent coffee per 400 mL water). Furthermore, spent coffee defatting and extract lyophilization allowed us to obtain spent coffee extracts powder with high antioxidant capacity that can be used as an ingredient or additive in food industry with potential preservation and functional properties

Coffee and spent coffee extracts protect against cell mutagens and inhibit growth of food-borne pathogen microorganisms

Coffee consumption decreases the risk of oxidative stress-related diseases. The by-product obtained after brewing process (spent coffee) also has antioxidant capacity. Spent coffee and coffee brews (filter and espresso) extracts were obtained from Arabica and Robusta coffees, respectively. Spent coffee showed slightly high amounts in chlorogenic acids, but caffeine content was similar to their respective coffee brew. All samples exhibited strong protection activity against indirect acting mutagen 2-AF (≤92%), whereas the protection against NPD (direct mutagen) was 12–35% (Ames Test). The growth inhibition of common food-borne pathogen and food spoilage microorganisms by coffee extracts was also studied. Spent coffee showed antimicrobial activity, mainly against Gram-positive bacteria (Staphylococcus aureus, Listeria monocytogenes) and yeast (Candida albicans). The role of phenolic acids, caffeine and melanoidins in the antimutagenic and antimicrobial activities is discussed. Thus, spent coffee extracts could be a potential source of bioactive compounds, thereby becoming a promising new functional food ingredient

In vitro studies on the stability in the proximal gastrointestinal tract and bioaccessibility in Caco-2 cells of chlorogenic acids from spent coffee grounds

Spent coffee grounds are a potential commercial source of substantial amounts of chlorogenic acids (CGAs). The aim of this study was to evaluate the stability of spent coffee CGAs using in vitro simulated gastroduodenal digestion and to investigate their potential absorption using an in vitro Caco-2 model of human small intestinal epithelium. During in vitro digestion, lactones were partially degraded while caffeoylquinic and feruloylquinic acids were much more stable. Transport and metabolism studies showed that 1% of the total CGAs were absorbed and transported from the apical to the basolateral side of a Caco-2 cell monolayer after 1 h. Lactones and coumaroylquinic acids showed the rate of highest absorption. Caco-2 cells possessed low metabolic activity. In conclusion, spent coffee extracts contain large amounts of CGAs, which remained bioaccessible across the intestinal barrier, albeit to a relatively low degree

Evaluation of spent coffee obtained from the most common coffeemakers as a source of hydrophilic bioactive compounds

The main hydrophilic antioxidant compounds (3-, 4-, and 5-monocaffeoylquinic and 3,4-, 3,5-, and 4,5-dicaffeoylquinic acids, caffeine, and browned compounds, including melanoidins) and the antioxidant capacity (Folin-Ciocalteu, ABTS, DPPH, Fremy's salt, and TEMPO) were evaluated in Arabica and Robusta spent coffee obtained from the preparation of coffee brews with the most common coffeemakers (filter, espresso, plunger, and mocha). All spent coffee grounds, with the exception of those from the mocha coffeemaker, had relevant amounts of total caffeoylquinic acids (6.22-13.24 mg/g of spent coffee), mainly dicaffeoylquinic acids (3.31-5.79 mg/g of spent coffee), which were 4-7-fold higher than in their respective coffee brews. Caffeine ranged from 3.59 to 8.09 mg/g of spent coffee. The antioxidant capacities of the aqueous spent coffee extracts were 46.0-102.3% (filter), 59.2-85.6% (espresso), and <42% (plunger) in comparison to their respective coffee brews. This study obtained spent coffee extracts with antioxidant properties that can be used as a good source of hydrophilic bioactive compounds

Spent coffee as a new source of bioaccessible and bioactive compounds with antimutagenic and antimicrobial activity

Los subproductos (posos) resultantes de la preparación de la bebida de café son una potencial fuente de compuestos bioactivos. El objetivo de la tesis fue evaluar los principales compuestos bioactivos de los posos del café, su bioaccesibilidad, y su potencial actividad antimutagénica y antimicrobiana. Previamente, se optimizó el método de extracción de antioxidantes aplicando el desgrasado y la liofilización. La cuantificación del contenido de compuestos fenólicos y cafeína de los extractos de posos de café Arábica de filtro y de Robusta expreso, se realizó por HPLC‐DAD‐MS. Se estimó el contenido total de compuestos fenólicos (libres y unidos) tras aplicar tres tratamientos (alcalino, ácido, salino). Se identificaron y cuantificaron un total de 36 ácidos clorogénicos (CGA) libres, mostrando los extractos de posos Arábica y Robusta una concentración de 329 y 345 μmol/g, respectivamente. Se estimó que la mitad del total de los compuestos fenólicos están unidos a macromoléculas como las melanoidinas, principalmente por enlaces no covalentes. La mayoría de los CGA de los extractos de posos de café permanecen bioaccesibles tras una digestión gastroduodenal in vitro (89‐92%). Los mayoritarios –ácidos cafeoilquínicos (CQAs) y feruloilquínicos (FQAs)‐ son los más estables, mientras que las lactonas se degradan parcialmente. Sin embargo, la absorción y transporte de los CGAs a través una monocapa de células Caco‐2 (células intestinales) fue muy limitada (1% dosis inicial). Por tanto, se requerirían estudios in vivo para evaluar la biodisponibilidad de los compuestos bioactivos de los extractos de posos del café. Los extractos de posos de café mostraron una elevada protección frente al mutágeno de acción indirecta (hasta 92%), mientras que frente al mutágeno de acción directa fue del 12‐35% (Test de Ames); siendo los fenólicos con ácido cafeico altamente efectivos. Finalmente, se evaluó la capacidad de los extractos de posos de café para inhibir el crecimiento de microrganismos patógenos y contaminantes comunes en alimentos, mostrando mayor actividad antimicrobiana frente a bacterias Gram‐positivas (Staphylococcus aureus, Listeria monocytogenes) y levaduras (Candida albicans). En conclusión, todos los resultados muestran que los posos de café son una fuente accesible y sostenible de compuestos bioactivos con potenciales beneficios para la salud, por lo que podrían ser utilizados como ingredientes en alimentos funcionales.Spent coffee is the main by‐product of the coffee brew preparation and a promising source of bioactive compounds. The aim of this work was to evaluate the main bioactive compounds of spent coffee extracts, their bioaccessibility, as well as their antimutagenic and antimicrobial activity. Previously, the extraction method of antioxidant compounds was improved by applying defatting and lyophilisation. The phenolics and caffeine content of Arabica filter and Robusta espresso spent coffee was measured by HPLC‐DAD‐MS, and the total content of phenolic compounds (free and bound) was assessed after applying three treatments (alkaline, acid, saline). A total of 36 free chlorogenic acids (CGA) were identified and quantified showing that Arabica and Robusta spent coffee extracts have 329 and 345 μmol of free CGA /g, respectively. Furthermore, bound compounds were estimated as half of the total phenolic content, due to presence of phenolics linked to macromolecules like melanoidins, mainly by non‐covalent interactions. The majority of CGAs of spent coffee extracts remain bioaccessible after an in vitro simulated gastroduodenal digestion (89‐92%), being the major compounds ‐ caffeoylquinic (CQAs) and feruloylquinic (FQAs) acids‐ those with a low degradation, whereas lactones were partially degraded. However, CGAs showed very limited absorption and transport (1% initial dose) across the Caco‐2 human cell monolayer (intestinal epithelium). Therefore, in vivo studies are required to assess bioavailability of spent coffee bioactive compounds. Spent coffee extracts exhibited strong protection activity against indirect acting mutagen (up to 92%), whereas the protection against a direct acting mutagen was 12‐35% (Ames Test), being phenolics with a caffeic acid highly effective. The growth inhibition of common food‐borne pathogen and food spoilage microorganisms by coffee extracts was also studied. Spent coffee extracts showed antimicrobial activity, mainly against Gram‐positive bacteria (Staphylococcus aureus, Listeria monocytogenes) and yeast (Candida albicans). In conclusion, all the results support the idea that spent coffee is an accessible, sustainable, and major source of bioactive compounds with potential health benefits in order to be applied as ingredients of functional foods

Spent coffee as a new source of bioaccessible and bioactive compounds with antimutagenic and antimicrobial activity

Los subproductos (posos) resultantes de la preparación de la bebida de café son una potencial fuente de compuestos bioactivos. El objetivo de la tesis fue evaluar los principales compuestos bioactivos de los posos del café, su bioaccesibilidad, y su potencial actividad antimutagénica y antimicrobiana. Previamente, se optimizó el método de extracción de antioxidantes aplicando el desgrasado y la liofilización. La cuantificación del contenido de compuestos fenólicos y cafeína de los extractos de posos de café Arábica de filtro y de Robusta expreso, se realizó por HPLC‐DAD‐MS. Se estimó el contenido total de compuestos fenólicos (libres y unidos) tras aplicar tres tratamientos (alcalino, ácido, salino). Se identificaron y cuantificaron un total de 36 ácidos clorogénicos (CGA) libres, mostrando los extractos de posos Arábica y Robusta una concentración de 329 y 345 μmol/g, respectivamente. Se estimó que la mitad del total de los compuestos fenólicos están unidos a macromoléculas como las melanoidinas, principalmente por enlaces no covalentes. La mayoría de los CGA de los extractos de posos de café permanecen bioaccesibles tras una digestión gastroduodenal in vitro (89‐92%). Los mayoritarios –ácidos cafeoilquínicos (CQAs) y feruloilquínicos (FQAs)‐ son los más estables, mientras que las lactonas se degradan parcialmente. Sin embargo, la absorción y transporte de los CGAs a través una monocapa de células Caco‐2 (células intestinales) fue muy limitada (1% dosis inicial). Por tanto, se requerirían estudios in vivo para evaluar la biodisponibilidad de los compuestos bioactivos de los extractos de posos del café. Los extractos de posos de café mostraron una elevada protección frente al mutágeno de acción indirecta (hasta 92%), mientras que frente al mutágeno de acción directa fue del 12‐35% (Test de Ames); siendo los fenólicos con ácido cafeico altamente efectivos. Finalmente, se evaluó la capacidad de los extractos de posos de café para inhibir el crecimiento de microrganismos patógenos y contaminantes comunes en alimentos, mostrando mayor actividad antimicrobiana frente a bacterias Gram‐positivas (Staphylococcus aureus, Listeria monocytogenes) y levaduras (Candida albicans). En conclusión, todos los resultados muestran que los posos de café son una fuente accesible y sostenible de compuestos bioactivos con potenciales beneficios para la salud, por lo que podrían ser utilizados como ingredientes en alimentos funcionales.Spent coffee is the main by‐product of the coffee brew preparation and a promising source of bioactive compounds. The aim of this work was to evaluate the main bioactive compounds of spent coffee extracts, their bioaccessibility, as well as their antimutagenic and antimicrobial activity. Previously, the extraction method of antioxidant compounds was improved by applying defatting and lyophilisation. The phenolics and caffeine content of Arabica filter and Robusta espresso spent coffee was measured by HPLC‐DAD‐MS, and the total content of phenolic compounds (free and bound) was assessed after applying three treatments (alkaline, acid, saline). A total of 36 free chlorogenic acids (CGA) were identified and quantified showing that Arabica and Robusta spent coffee extracts have 329 and 345 μmol of free CGA /g, respectively. Furthermore, bound compounds were estimated as half of the total phenolic content, due to presence of phenolics linked to macromolecules like melanoidins, mainly by non‐covalent interactions. The majority of CGAs of spent coffee extracts remain bioaccessible after an in vitro simulated gastroduodenal digestion (89‐92%), being the major compounds ‐ caffeoylquinic (CQAs) and feruloylquinic (FQAs) acids‐ those with a low degradation, whereas lactones were partially degraded. However, CGAs showed very limited absorption and transport (1% initial dose) across the Caco‐2 human cell monolayer (intestinal epithelium). Therefore, in vivo studies are required to assess bioavailability of spent coffee bioactive compounds. Spent coffee extracts exhibited strong protection activity against indirect acting mutagen (up to 92%), whereas the protection against a direct acting mutagen was 12‐35% (Ames Test), being phenolics with a caffeic acid highly effective. The growth inhibition of common food‐borne pathogen and food spoilage microorganisms by coffee extracts was also studied. Spent coffee extracts showed antimicrobial activity, mainly against Gram‐positive bacteria (Staphylococcus aureus, Listeria monocytogenes) and yeast (Candida albicans). In conclusion, all the results support the idea that spent coffee is an accessible, sustainable, and major source of bioactive compounds with potential health benefits in order to be applied as ingredients of functional foods

Coffee and spent coffee extracts protect against cell mutagens and inhibit growth of food-borne pathogen microorganisms

Coffee consumption decreases the risk of oxidative stress-related diseases. The by-product obtained after brewing process (spent coffee) also has antioxidant capacity. Spent coffee and coffee brews (filter and espresso) extracts were obtained from Arabica and Robusta coffees, respectively. Spent coffee showed slightly high amounts in chlorogenic acids, but caffeine content was similar to their respective coffee brew. All samples exhibited strong protection activity against indirect acting mutagen 2-AF (≤92%), whereas the protection against NPD (direct mutagen) was 12–35% (Ames Test). The growth inhibition of common food-borne pathogen and food spoilage microorganisms by coffee extracts was also studied. Spent coffee showed antimicrobial activity, mainly against Gram-positive bacteria (Staphylococcus aureus, Listeria monocytogenes) and yeast (Candida albicans). The role of phenolic acids, caffeine and melanoidins in the antimutagenic and antimicrobial activities is discussed. Thus, spent coffee extracts could be a potential source of bioactive compounds, thereby becoming a promising new functional food ingredient