Academic literature on the topic 'The most abundant chlorogenic acid in green coffee beans'

Caffeoyl-, feruloyl- and dicaffeoylquinic acids (chlorogenic acids) in infusions from green and medium roasted coffee beans were identified and quantified by reverse phase HPLC with photodiode array and MS³ detection prior to assessment of the antioxidant activity using an HPLC system with post-column on-line antioxidant detection based on 2,2'-azinobis-3-ethylbenzothiazoline-6-sulphonic acid radical scavenging activity. Caffeoylquinic acids were the most abundant antioxidants and roasting induced isomerisation with a decline in 5-O-caffeoylquinic acid and concomitant increases in the 3- and 4-O-derivatives. This did not affect the level of caffeoylquinic acid-derived antioxidant activity in the roasted coffee. Roasting did, however, result in the appearance of additional unidentified HPLC peaks with antioxidant activity. Because of this and an increase in the antioxidant activity of components that did not elute from the reversed phase HPLC column, the antioxidant capacity of the beverage derived from medium roast beans was double that of the unroasted coffee. The antioxidant activity of coffees that have undergone different degrees of roasting would, therefore, appear to be due to combinations of different components. The effect of roasting on chlorogenic acids in coffee beans is considered, and the possible contribution of Maillard reaction products to the antioxidant capacity of roasted coffees is discussed.

Chlorogenic acids (CGA) are the most abundant phenolic compounds in green coffee beans and in the human diet and have been suggested to mitigate several cardiometabolic risk factors. Here, we aimed to evaluate the effect of a water-based standardized green coffee extract (GCE) on cardiometabolic parameters in ApoE-/- mice and to explore the potential underlying mechanisms. Mice were fed an atherogenic diet without (vehicle) or with GCE by gavage (equivalent to 220 mg/kg of CGA) for 14 weeks. We assessed several metabolic, pathological, and inflammatory parameters and inferred gut microbiota composition, diversity, and functional potential. Although GCE did not reduce atherosclerotic lesion progression or plasma lipid levels, it induced important favorable changes. Specifically, improved metabolic parameters, including fasting glucose, insulin resistance, serum leptin, urinary catecholamines, and liver triglycerides, were observed. These changes were accompanied by reduced weight gain, decreased adiposity, lower inflammatory infiltrate in adipose tissue, and protection against liver damage. Interestingly, GCE also modulated hepatic IL-6 and total serum IgM and induced shifts in gut microbiota. Altogether, our results reveal the cooccurrence of these beneficial cardiometabolic effects in response to GCE in the same experimental model and suggest potential mediators and pathways involved.

Coffee is one of the oldest and most consumed beverages. The raw material for obtaining a good quality coffee drink is the grain. Bioactive compounds and organic acids in coffee beans are reflections of a series of attributes that, together, confer to the coffee peculiar flavor and aroma. This study aimed to identify trigonelline, chlorogenic acid, caffeine and organic acids in green coffee beans, and to validate the chromatographic method using High-Performance Liquid Chromatography (HPLC). Coffea arabica green coffee beans were used in this experiment. Trigonelline, chlorogenic acid, caffeine, and organic acids were identified and quantified by HPLC. Selectivity, linearity, limit of detection, limit of quantification, precision, and accuracy were used to validate the methods. Three bioactive compounds (trigonelline, chlorogenic acid, and caffeine) and seven organic acids (oxalic, citric, malic, quinic, succinic, lactic, and acetic acids) were quantified in the samples. The mean values for trigonelline, chlorogenic acid (5-ACQ), and caffeine ranged from 1.28 to 1.66, 3.47 to 4.73 and 1.26 to 1.59 g 100g-1, respectively. The values of organic acids, as well as the phenolic compounds, agree with those reported by the literature for green coffee beans of C. arabica. The validation parameters allowed the method to be considered linear, exact, and precise. Therefore, it resulted in a method reliable for studies of the composition of food matrix or quality control of green coffee beans.

Coffee is one of the most widely consumed beverages worldwide. It is usually identified as a stimulant because of a high content of caffeine. However, caffeine is not the only coffee bioactive component. The coffee beverage is in fact a mixture of a number of bioactive compounds such as polyphenols, especially chlorogenic acids (in green beans) and caffeic acid (in roasted coffee beans), alkaloids (caffeine and trigonelline), and the diterpenes (cafestol and kahweol). Extensive research shows that coffee consumption appears to have beneficial effects on human health. Regular coffee intake may protect from many chronic disorders, including cardiovascular disease, type 2 diabetes, obesity, and some types of cancer. Importantly, coffee consumption seems to be also correlated with a decreased risk of developing some neurodegenerative conditions such as Alzheimer’s disease, Parkinson’s disease, and dementia. Regular coffee intake may also reduce the risk of stroke. The mechanism underlying these effects is, however, still poorly understood. This review summarizes the current knowledge on the neuroprotective potential of the main bioactive coffee components, i.e., caffeine, chlorogenic acid, caffeic acid, trigonelline, kahweol, and cafestol. Data from both in vitro and in vivo preclinical experiments, including their potential therapeutic applications, are reviewed and discussed. Epidemiological studies and clinical reports on this matter are also described. Moreover, potential molecular mechanism(s) by which coffee bioactive components may provide neuroprotection are reviewed.

There are different types of coffee processing methods. The wet (WP) and dry processing (DP) methods are widely practiced in different parts of coffee-growing countries. There is also a digestive bioprocessing method in which the most expensive coffee is produced. The elephant dung coffee is produced using the digestive bioprocessing method. In the present experiment, the antioxidant activity and volatile compounds of coffee that have been processed using different methods were compared. The antioxidant activity, total phenolic content (TPC), total flavonoid content (TFC), and total tannin content (TTC) of green coffee beans from all treatments were higher as compared to roasted coffee beans. Regarding the green coffee beans, the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of elephant dung coffee beans was higher as compared to that of the DP and WP coffee beans. The green coffee beans had higher DPPH activity and ferric reducing antioxidant power (FRAP) value compared to the roasted coffee beans. The green beans of elephant dung coffee had a high TPC than the beans obtained by WP and DP methods. TFC in elephant dung coffee in both green and roasted condition was improved in contrast to the beans processed using dry and wet methods. The elephant dung coffee had an increased TTC in comparison to the DP and WP coffee (green beans). About 37 volatile compounds of acids, alcohols, aldehydes, amide, esters, ethers, furans, furanones, ketones, phenols, pyrazines, pyridines, Heterocyclic N, and pyrroles functional classes have been found. Some of the most abundant volatile compounds detected in all treatments of coffee were 2-furanmethanol, acetic acid, 2-methylpyrazine, 2,6-dimethylpyrazine, pyridine, and 5-methylfurfural. Few volatile compounds have been detected only in elephant dung coffee. The principal component analysis (PCAs) was performed using the percentage of relative peak areas of the volatile compound classes and individual volatile compounds. This study will provide a better understanding of the impacts of processing methods on the antioxidants and volatile compounds of coffee.

Arabica coffee is the most popular variety of coffee among the people because it has a more complex flavor than other coffee varieties. This study aims to determine sensory properties and non-volatile components in Arabica coffee fermented with sugar addition. The sensory assessment showed that the best cupping score was the samples fermented with the addition of 0.55% fructose with a total score of 85.25 compared to honey (H) and Fullwash (FW) samples. Fermentation with the addition of 0.55% fructose could produce better coffee compared to samples (H) and (FW). Fermentation with the sugar addition of 0.55% could affect non-volatile components such as soluble sugars, organic acids, amino acids, caffeine, and chlorogenic acid. The content of chlorogenic acid and caffeine analysed by HPLC was found relatively stable in green and roasted beans. Amino acids analysed by LCMS showed glutamate was the highest amino acid in all samples and were supposed to have a role in Maillard reaction contributing to coffee flavor. In conclusion, fermentation with the addition of 0.55% sugar in coffee processing could generally enhance the coffee flavor for brew taste with its potential as functional drink.

We aimed to analyze the chemical compositions in Arabica coffee bean extracts, assess the relevant antioxidant and iron-chelating activities in coffee extracts and instant coffee, and evaluate the toxicity in roasted coffee. Coffee beans were extracted using boiling, drip-filtered and espresso brewing methods. Certain phenolics were investigated including trigonelline, caffeic acid and their derivatives, gallic acid, epicatechin, chlorogenic acid (CGA) and their derivatives, p-coumaroylquinic acid, p-coumaroyl glucoside, the rutin and syringic acid that exist in green and roasted coffee extracts, along with dimethoxycinnamic acid, caffeoylarbutin and cymaroside that may be present in green coffee bean extracts. Different phytochemicals were also detected in all of the coffee extracts. Roasted coffee extracts and instant coffees exhibited free-radical scavenging properties in a dose-dependent manner, for which drip coffee was observed to be the most effective (p < 0.05). All coffee extracts, instant coffee varieties and CGA could effectively bind ferric ion in a concentration-dependent manner resulting in an iron-bound complex. Roasted coffee extracts were neither toxic to normal mononuclear cells nor breast cancer cells. The findings indicate that phenolics, particularly CGA, could effectively contribute to the iron-chelating and free-radical scavenging properties observed in coffee brews. Thus, coffee may possess high pharmacological value and could be utilized as a health beverage.

Chlorogenic acids are major secondary metabolites found in coffee seeds. The accumulation of chlorogenic acids and free quinic acids was studied in Coffea arabica cv. Tall Mokka and Coffea canephora seeds. Growth stages are specified from I to V, corresponding to rapid expansion and pericarp growth (I), endosperm formation (II), mature (green) (III), ripening (pink) (IV), and fully ripened (red) (V) stages. We detected monocaffeoylquinic acids (3CQA, 4CQA and 5CQA), dicaffeoylquinic acids (3,4diCQA, 3,5diCQA and 4,5diCQA) and a monoferuloylquinic acid (5FQA) in whole fruits (stage I), pericarps and seeds. The most abundant chlorogenic acid was 5CQA, which comprised 50-60% of the total of C. arabica and 45-50% of C. canephora seeds. The content of dicaffeoylquinic acid, mainly 3,5d diCQA, was high in C. canephora. A high content of 5FQA was found in seeds of stages III to V, especially in C. canephora. Total chlorogenic acids were accumulated up to 14 mg per fruit in C. arabica and 17 mg in C. canephora, respectively. In contrast, free quinic acid varied from 0.4-2.0 mg (C. arabica) and 0.2-4.0 mg (C. canephora) per fruit during growth. High biosynthetic activity of 5CQA, which was estimated via the incorporation of [U-14C]phenylalanine into chlorogenic acids, was found in young fruits (perisperm and pericarp) in stage I, and in developing seeds (endosperm) in stages II and III. The biosynthetic activity of chlorogenic acids was clearly reduced in ripening and ripe seeds, especially in C. canephora. Transcripts of PAL1, C3′H and CCoAMT, three genes related to the chlorogenic acid biosynthesis, were detected in every stage of growth, although the amounts were significantly less in stage V. Of these genes, CCoAMT, a gene for FQA biosynthesis, was expressed more weakly in stage I. The transcript level of CCoAMT was higher in seeds than in pericarp, but the reverse was found in PAL1. The pattern of expression of genes for the CQA and FQA synthesis is roughly related to the estimated biosynthetic activity, and to the accumulation pattern of chlorogenic acids.

ABSTRACT The postharvest treatment and processing of fresh coffee cherries can impact the quality of the unroasted green coffee beans. In the present case study, freshly harvested Arabica coffee cherries were processed through two different wet and dry methods to monitor differences in the microbial community structure and in substrate and metabolite profiles. The changes were followed throughout the postharvest processing chain, from harvest to drying, by implementing up-to-date techniques, encompassing multiple-step metagenomic DNA extraction, high-throughput sequencing, and multiphasic metabolite target analysis. During wet processing, a cohort of lactic acid bacteria (i.e., Leuconostoc, Lactococcus, and Lactobacillus) was the most commonly identified microbial group, along with enterobacteria and yeasts (Pichia and Starmerella). Several of the metabolites associated with lactic acid bacterial metabolism (e.g., lactic acid, acetic acid, and mannitol) produced in the mucilage were also found in the endosperm. During dry processing, acetic acid bacteria (i.e., Acetobacter and Gluconobacter) were most abundant, along with Pichia and non-Pichia (Candida, Starmerella, and Saccharomycopsis) yeasts. Accumulation of associated metabolites (e.g., gluconic acid and sugar alcohols) took place in the drying outer layers of the coffee cherries. Consequently, both wet and dry processing methods significantly influenced the microbial community structures and hence the composition of the final green coffee beans. This systematic approach to dissecting the coffee ecosystem contributes to a deeper understanding of coffee processing and might constitute a state-of-the-art framework for the further analysis and subsequent control of this complex biotechnological process. IMPORTANCE Coffee production is a long process, starting with the harvest of coffee cherries and the on-farm drying of their beans. In a later stage, the dried green coffee beans are roasted and ground in order to brew a cup of coffee. The on-farm, postharvest processing method applied can impact the quality of the green coffee beans. In the present case study, freshly harvested Arabica coffee cherries were processed through wet and dry processing in four distinct variations. The microorganisms present and the chemical profiles of the coffee beans were analyzed throughout the postharvest processing chain. The up-to-date techniques implemented facilitated the investigation of differences related to the method applied. For instance, different microbial groups were associated with wet and dry processing methods. Additionally, metabolites associated with the respective microorganisms accumulated on the final green coffee beans.

Coffee contains caffeine and chlorogenic acid (CGA) as the main constituent benefiting human health. Extract of green coffee beans (GCB) has some limitations in terms of its unpleasant flavour, aroma, and phytoconstituents bioactivity. This study aimed to encapsulate the crude ethyl acetate (EtOAc) extracts of Gayo Robusta GCB (Coffea canephora) to overcome its limitation. Microencapsulation was carried out by spray drying method using whey protein concentrate (WPC) as a coating material to produce nutraceutical supplement microparticles. The microparticles size, morphology, and physicochemical characteristics were investigated. We found that the yield of microparticles was 39.5%, volume diameter was1.367 µm, and span was 1.162 µm. The morphology of the microparticles was irregular microspheres particle with dense, smoothness, wrinkle, shrivel, compactness, and homogeneous structure shape particles. The physicochemical properties measurentment indicated that it has scavenging radical activity value (RSA) 374.53 µg/mL, total phenol content (TPC) 6.92 g GAE/kg, caffeine content 9.12%, and CGA levels 7.19%. The spray drying microencapsulation by using WPC was able to engulf and package the unpleasant flavour and aroma of the crude extract of Gayo Robusta GCB, produce abundant yield of smaller and narrower particle, and protect and carry considerable amounts of phytoconstituents bioactivity.

Doutoramento em Bioquímica<br>Os polissacarídeos são os componentes maioritários dos grãos de café verde e torrado e da bebida de café. Os mais abundantes são as galactomananas, seguindo-se as arabinogalactanas. Durante o processo de torra, as galactomananas e arabinogalactanas sofrem modificações estruturais, as quais estão longe de estar completamente elucidadas devido à sua diversidade e à complexidade estrutural dos compostos formados. Durante o processo de torra, as galactomananas e arabinogalactanas reagem com proteínas, ácidos clorogénicos e sacarose, originando compostos castanhos de alto peso molecular contendo nitrogénio, designados de melanoidinas. As melanoidinas do café apresentam diversas atividades biológicas e efeitos benéficos para a saúde. No entanto, a sua estrutura exata e os mecanismos envolvidos na sua formação permanecem desconhecidos, bem como a relação estrutura-atividade biológica. A utilização de sistemas modelo e a análise por espectrometria de massa permitem obter uma visão global e, simultaneamente, detalhada das modificações estruturais nos polissacarídeos do café promovidas pela torra, contribuindo para a elucidação das estruturas e mecanismos de formação das melanoidinas. Com base nesta tese, oligossacarídeos estruturalmente relacionados com a cadeia principal das galactomananas, (β1→4)-Dmanotriose (Man3), e as cadeias laterais das arabinogalactanas, (α1→5)-Larabinotriose (Ara3), isoladamente ou em misturas com ácido 5-Ocafeoilquínico (5-CQA), o ácido clorogénico mais abundante nos grãos de café verde, e péptidos compostos por tirosina e leucina, usados como modelos das proteínas, foram sujeitos a tratamento térmico a seco, mimetizando o processo de torra. A oxidação induzida por radicais hidroxilo (HO•) foi também estudada, uma vez que estes radicais parecem estar envolvidos na modificação dos polissacarídeos durante a torra. A identificação das modificações estruturais induzidas por tratamento térmico e oxidativo dos compostos modelo foi feita por estratégias analíticas baseadas principalmente em espectrometria de massa, mas também em cromatografia líquida. A cromatografia de gás foi usada na análise de açúcares neutros e ligações glicosídicas. Para validar as conclusões obtidas com os compostos modelo, foram também analisadas amostras de polissacarídeos do café obtidas a partir de resíduo de café e café instantâneo. Os resultados obtidos a partir dos oligossacarídeos modelo quando submetidos a tratamento térmico (seco), assim como à oxidação induzida por HO• (em solução), indicam a ocorrência de despolimerização, o que está de acordo com estudos anteriores que reportam a despolimerização das galactomananas e arabinogalactanas do café durante a torra. Foram ainda identificados outros compostos resultantes da quebra do anel de açúcares formados durante o tratamento térmico e oxidativo da Ara3. Por outro lado, o tratamento térmico a seco dos oligossacarídeos modelo (individualmente ou quando misturados) promoveu a formação de oligossacarídeos com um maior grau de polimerização, e também polissacarídeos com novos tipos de ligações glicosídicas, evidenciando a ocorrência de polimerização através reações de transglicosilação não enzimática induzidas por tratamento térmico a seco. As reações de transglicosilação induzidas por tratamento térmico a seco podem ocorrer entre resíduos de açúcares provenientes da mesma origem, mas também de origens diferentes com formação de estruturas híbridas, contendo arabinose e manose como observado nos casos dos compostos modelo usados. Os resultados obtidos a partir de amostras do resíduo de café e de café instantâneo sugerem a presença de polissacarídeos híbridos nestas amostras de café processado, corroborando a ocorrência de transglicosilação durante o processo de torra. Além disso, o estudo de misturas contendo diferentes proporções de cada oligossacarídeo modelo, mimetizando regiões do grão de café com composição distinta em polissacarídeos, sujeitos a diferentes períodos de tratamento térmico, permitiu inferir que diferentes estruturas híbridas e não híbridas podem ser formadas a partir das arabinogalactanas e galactomananas, dependendo da sua distribuição nas paredes celulares do grão e das condições de torra. Estes resultados podem explicar a heterogeneidade de estruturas de melanoidinas formadas durante a torra do café. Os resultados obtidos a partir de misturas modelo contendo um oligossacarídeo (Ara3 ou Man3) e 5-CQA sujeitas a tratamento térmico a seco, assim como de amostras provenientes do resíduo de café, mostraram a formação de compostos híbridos compostos por moléculas de CQA ligadas covalentemente a um número variável de resíduos de açúcar. Além disso, os resultados obtidos a partir da mistura contendo Man3 e 5-CQA mostraram que o CQA atua como catalisador das reações de transglicosilação. Por outro lado, nas misturas modelo contendo um péptido, mesmo contendo também 5-CQA e sujeitas ao mesmo tratamento, observou-se uma diminuição na extensão das reações transglicosilação. Este resultado pode explicar a baixa extensão das reações de transglicosilação não enzimáticas durante a torra nas regiões do grão de café mais ricas em proteínas, apesar dos polissacarídeos serem os componentes maioritários dos grãos de café. A diminuição das reações de transglicosilação na presença de péptidos/proteínas pode dever-se ao facto de os resíduos de açúcares redutores reagirem preferencialmente com os grupos amina de péptidos/proteínas por reação de Maillard, diminuindo o número de resíduos de açúcares redutores disponíveis para as reações de transglicosilação. Além dos compostos já descritos, uma diversidade de outros compostos foram formados a partir dos sistemas modelo, nomeadamente derivados de desidratação formados durante o tratamento térmico a seco. Em conclusão, a tipificação das modificações estruturais promovidas pela torra nos polissacarídeos do café abre o caminho para a compreensão dos mecanismos de formação das melanoidinas e da relação estrutura-atividade destes compostos.<br>Polysaccharides are the major components of green and roasted coffee beans, and coffee brew. The most abundant ones are galactomannans, followed by arabinogalactans. During the roasting process, galactomannans and arabinogalactans undergo structural modifications that are far to be completely elucidated due to their diversity and complexity of the compounds formed. During the roasting process, galactomannans and arabinogalactans react with proteins, chlorogenic acids, and sucrose, originating high molecular weight brown compounds containing nitrogen, known as melanoidins. Several biological activities and beneficial health effects have been attributed to coffee melanoidins. However, their exact structures and the mechanisms involved in their formation remain unknown, as well as the structure-biological activity relationship. The use of model systems and mass spectrometry analysis allow to obtain an overall view and, simultaneously, detailed, of the structural modifications in coffee polysaccharides promoted by roasting, contributing to the elucidation of the structures and formation mechanisms of melanoidins. Based on this thesis, oligosaccharides structurally related to the backbone of galactomannans, (β1→4)-D-mannotriose, and the side chains of arabinogalactans, (α1→5)-Larabinotriose, alone or in mixtures with 5-O-caffeoylquinic acid, the most abundant chlorogenic acid in green coffee beans, and dipeptides composed by tyrosine and leucine, used as models of proteins, were submitted to dry thermal treatments, mimicking the coffee roasting process. The oxidation induced by hydroxyl radicals (HO•) was also studied, since these radicals seem to be involved in the modification of the polysaccharides during roasting. The identification of the structural modifications induced by thermal and oxidative treatment of the model compounds was performed mostly by mass spectrometry-based analytical strategies, but also using liquid chromatography. Gas chromatography was used in the analysis of neutral sugars and glycosidic linkages. To validate the conclusions achieved with the model compounds, coffee polysaccharide samples obtained from spent coffee grounds and instant coffee were also analysed. The results obtained from the model oligosaccharides when submitted to thermal treatment (dry) or oxidation induced by HO• (in solution) indicate the occurrence of depolymerization, which is in line with previous studies reporting the depolymerization of coffee galactomannans and arabinogalactans during roasting. Compounds resulting from sugar ring cleavage were also formed during thermal treatment and oxidative treatment of Ara3. On the other hand, the dry thermal treatment of the model oligosaccharides (alone or when mixed) promoted the formation of oligosaccharides with a higher degree of polymerization, and also polysaccharides with new type of glycosidic linkages, evidencing the occurrence of polymerization via non-enzymatic transglycosylation reactions induced by dry thermal treatment. The transglycosylation reactions induced by dry thermal treatment can occur between sugar residues from the same origin, but also of different origins, with formation of hybrid structures, containing arabinose and mannose in the case of the model compounds used. The results obtained from spent coffee grounds and instant coffee samples suggest the presence of hybrid polysaccharides in these processed coffee samples, corroborating the occurrence of transglycosylation during the roasting process. Furthermore, the study of mixtures containing different proportions of each model oligosaccharide, mimicking coffee bean regions with distinct polysaccharide composition, subjected to different periods of thermal treatment, allowed to infer that different hybrid and non-hybrid structures may be formed from arabinogalactans and galactomannans, depending on their distribution in the bean cell walls and on roasting conditions. These results may explain the heterogeneity of melanoidins structures formed during coffee roasting. The results obtained from model mixtures containing an oligosaccharide (Ara3 or Man3) and 5-CQA and subjected to dry thermal treatment, as well as samples derived from spent coffee grounds, showed the formation of hybrid compounds composed by CQA molecules covalently linked to a variable number of sugar residues. Moreover, the results obtained from the mixture containing Man3 and 5-CQA showed that CQA acts as catalyst of transglycosylation reactions. On the other hand, in the model mixtures containing a peptide, even if containing 5-CQA and subjected to the same treatment, it was observed a decrease in the extent of transglycosylation reactions. This outcome can explain the low extent of non-enzymatic transglycosylation reactions during roasting in coffee bean regions enriched in proteins, although polysaccharides are the major components of the coffee beans. The decrease of transglycosylation reactions in the presence of peptides/proteins can be related with the preferential reactivity of reducing residues with the amino groups of peptides/proteins by Maillard reaction, decreasing the number of reducing residues available to be directly involved in the transglycosylation reactions. In addition to the compounds already described, a diversity of other compounds were formed from model systems, namely dehydrated derivatives formed during dry thermal treatment. In conclusion, the identification of the structural modifications in coffee polysaccharides promoted by roasting pave the way to the understanding of the mechanisms of formation of melanoidins and structure-activity relationship of these compounds.