Bitterness Of Coffee Research Articles

Study on Masking the Bitterness of Chinese Medicine Decoction-Mate.

Background Traditional Chinese medicine decoction (TCMD) is an oral liquid made by decocting crude medicinal compounds with water. It has complex compositions and diverse odor and taste, most of which have an unacceptable level of bitterness which seriously affects patients' medication compliance. To solve this problem, a variety of taste-masking pathways and different types of taste-masking excipients were combined, using the application of coffee-mate to mask the bitterness of coffee as an existing example. Three composite taste-masking adjuvants were developed to improve the taste of TCMD, referred to as the Chinese Medicine Decoction-Mate (CMD-M). However, whether CMD-M has a good taste-masking effect and whether it affects the chemical compositions and pharmacological effects of the medicine remain unclear. Method The commonly used pediatric medicine Qingre Huazhi Decoction (QRHZD) and the personalized decoctions used in clinical practices were used as the masking research carriers. The taste-masking effect of CMD-M on QRHZD was evaluated by both healthy volunteers and an electronic tongue, and the personalized decoctions were evaluated by clinical subjects. The changes of chemical components of QRHZD before and after taste-masking were evaluated by HPLC. The changes in anti-inflammatory effects were evaluated by establishing mice as an acute inflammatory model. Results The taste-masking effect evaluation results showed that the bitterness of QRHZD was significantly reduced after adding CMD-M. There was no significant difference in the relative peak areas change rate and total peak areas ratio of common peaks of QRHZD before and after taste-masking (P > 0.05), shown by HPLC analysis. The inhibitory rates of QRHZD on ear swelling in mice before and after taste-masking also showed no significant difference (P > 0.05). Conclusions CMD-M can effectively mask the bitterness of decoctions while bringing no significant difference overall in chemical compositions and pharmacological effects before and after QRHZD masking.

Pyrrolomorpholine Spiroketal Alkaloids Present in Roasted Beans of Yunnan Arabica Coffee

Background: Coffee is one of the most commonly consumed drinks around the world. During the coffee roasting process, sugars and amines undergo a violent Maillard reaction, resulting in a large number of volatile and non-volatile components. These ingredients have a huge impact on the formation of coffee flavor. In addition, many Maillard products in coffee have also been proven to exert antioxidative, anti-inflammatory effects, etc. Objective: The objective of this research is to discover non-volatile Maillard reaction products in roasted coffee beans. Results and Methods: A pair of enantiomers pyrrolomorpholine spiroketal alkaloids 1a and 1b were isolated from roasted beans of Yunnan coffea Arabica. Their planar structures were elucidated by extensive spectroscopic analysis, HRESIMS spectra and X-Ray diffraction. Conclusion: Two pyrrolomorpholine spiroketal alkaloids were isolated from roasted Arabica coffee beans. And their formation pathway via Maillard reaction was deduced. Their influence on the formation of coffee bitterness and biological functions is worthy of being further studied.

Numerous Compounds Orchestrate Coffee's Bitterness.

Coffee is one of the most consumed hot beverages worldwide and is highly regarded because of its stimulating effect despite having a pronounced bitterness. Even though numerous bitter ingredients have been identified, the detailed molecular basis for coffee's bitterness is not well understood except for caffeine, which activates five human bitter taste receptors. We elucidated the contribution of other bitter coffee constituents in addition to caffeine with functional calcium imaging experiments using mammalian cells expressing the cDNAs of human bitter taste receptors, sensory experiments, and in silico modeling approaches. We identified two human bitter taste receptors, TAS2R43 and TAS2R46, that responded to the bitter substance mozambioside with much higher sensitivity than to caffeine. Further, the structurally related bitter substances bengalensol, cafestol, and kahweol also activated the same pair of bitter taste receptors much more potently than the prototypical coffee bitter substance caffeine. However, for kahweol, a potent but weak activator of TAS2R43 and TAS2R46, we observed an inhibitory effect when simultaneously applied together with mozambioside to TAS2R43 expressing cells. Molecular modeling experiments showed overlapping binding sites in the receptor's ligand binding cavity that suggest that the partial agonist kahweol might be useful to reduce the overall bitterness of coffee-containing beverages. Taken together, we found that the bitterness of coffee is determined by a complex interaction of multiple bitter compounds with several human bitter taste receptors.

Quantification of bitterness of coffee in the presence of high-potency sweeteners using taste sensors

Electronic tongues have been identified as useful tools for quantifying the taste of food and beverages. However, the bitterness evaluation of coffee in the presence of high-potency sweeteners has not been performed yet. In this study, we investigated an approach to quantify the bitterness of coffee with different roasting degrees and the sweetness of acesulfame potassium (Ace K) added to the coffee using taste sensors with lipid polymer membranes. A formula for predicting coffee bitterness with the addition of Ace K was proposed using the responses of a bitterness sensor and a sweetness sensor. We found that the predicted coffee bitterness showed a good correlation with human taste.

Review: Peran Enzim dalam Meningkatkan Kualitas Kopi

Indonesia is the third largest coffee producing nation in the world after Brazil and Vietnam. The types and the characteristics of Indonesian coffee are different in each area but the main important factor of consumer acceptance depends on its bitterness level. Chlorogenic acid lactone is a compounds that play an important role as contributor to the coffee bitterness that are formed during the roasting process of coffee bean because of its precursor chlorogenic acid. Chlorogenic acid is commonly found in many plants. One of them can be found in coffee with high concentration. Chlorogenic acid lactone (bitter compound) can be hydrolyzed to chlorogenic acid (non-bitter compound) using hog liver esterase and chlorogenate esterase. This study aimed to analyze the use of these enzymes to decrease the level of bitterness in coffee. The results indicated that HLE and chlorogenate esterase effectively hydrolyzed chlorogenic acid lactones in coffee. Based on the sensory test, coffee extracts treated with enzymes were less bitter than the untreated coffee extracts. If it was associated with Indonesian local coffee then the method can be done with chlorogenate esterase that was in accordance with the legal guarantee of halal product.

Highly Sensitive Multichannel Interdigitated Capacitor Based Bitterness Sensor

In this study, we propose a multichannel interdigitated capacitor (IDC) sensor for detecting the bitterness of coffee. The oper-ating principle of the device is based on the variation in capacitance of a sensing membrane in contact with a bitter solution. Four solvatochromic dyes, namely, Nile red, Reichardt’s dye, auramine-O, and rhodamine-B, were mixed with polyvinylchloride (PVC) and N,N-dimethylacetamide (DMAC), to create four different types of bitter-sensitive solutions. These solutions were then individually inserted into four interdigitated electrodes (IDEs) using a spin coater, to prepare four distinct IDC sensors. The sensors are capable of detecting bitterness-inducing chemical compounds in any solution, at concentrations of approximately 1 μM to 1 M. The sensitivity of the IDC bitterness sensor containing the Reichardt''s dye sensing-membrane was approximately 1.58 nF/decade. The multichannel sensor has a response time of approximately 6 s, and an approximate recovery time of 5 s. The proposed sensor offers a stable sensing response and linear sensing performance over a wide mea-surement range, with a correlation coefficient (R2) of approximately 0.972.

Selective enzymatic hydrolysis of chlorogenic acid lactones in a model system and in a coffee extract. Application to reduction of coffee bitterness

Chlorogenic acid lactones have been identified as key contributors to coffee bitterness. These compounds are formed during roasting by dehydration and cyclization of their precursors, the chlorogenic acids (CGAs). In the present study, we investigated an approach to decompose these lactones in a selective way without affecting the positive coffee attributes developed during roasting. A model system composed of (3-caffeoylquinic acid lactone (3-CQAL), 4- caffeoyl quinic acid lactone (4-CQAL), and 4-feruloylquinic acid lactone (4-FQAL)) was used for the screening of enzymes before treatment of the coffee extracts. Hog liver esterase (HLE) hydrolyzed chlorogenic acid lactones (CQALs, FQALs) selectively, while chlorogenate esterase hydrolyzed all chlorogenic acids (CQAs, FQAs) and their corresponding lactones (CQALs, FQALs) in a non-selective way. Enzymatically treated coffee samples were evaluated for their bitterness by a trained sensory panel and were found significantly less bitter than the untreated samples.

Caffeine metabolism rate influences coffee perception, preferences and intake

Several factors – genetic, demographic and environmental – contribute to individual differences in sensitivity to the pharmacological effects of caffeine. Caffeine metabolism influences coffee consumption, but its effect on bitterness perception in, and preference for, coffee is unknown.This study explores the possible relationship between caffeine metabolism rate and coffee preferences and consumption habits. In addition, the extent to which caffeine metabolism interacted with variations in bitterness perception was investigated. Caffeine metabolism rate was assayed by competitive immuno-enzymatic assay in one-hundred thirty-five coffee consumers who provided saliva samples after 12h caffeine abstinence and at 30 and 90min after ingestion of caffeine (100mg). A caffeine metabolism index (CmI) was computed as the ratio between the amount of residual caffeine in saliva 60min after the adsorption peak and the amount of caffeine at the adsorption peak corrected with the baseline. Ninety-one subjects were selected to investigate the relationships between inter-individual variation in caffeine metabolism, bitterness perception and coffee preference. Subjects rated liking for, and sourness, bitterness and astringency of, six unsweetened and freely sweetened coffee samples varying in roasting degree, caffeine content and bitterness. They also rated the bitterness of six caffeine and six quinine (equi-intense) solutions. Finally, subjects choose coffee to drink on the basis of a label (strong vs balanced flavor) both after caffeine abstinence and after no restrictions on caffeine intake. The CmI was strongly associated with the frequency of daily coffee consumption. Subjects with lower CmI gave higher bitterness ratings than other subjects for both coffee and caffeine solutions, but not for quinine solutions. They also added more sugar to the coffee samples. Following caffeine abstinence, all subjects chose the “strong flavor” coffee, while without caffeine restrictions, subjects with lower CmI preferentially tended to choose the “balanced flavor” coffee. These results provide the first link between caffeine metabolism and bitterness perception, and to the use of sugar to modify coffee bitterness.

First report on mangiferin (C-glucosyl-xanthone) isolated from leaves of a wild coffee plant, Coffea pseudozanguebariae (Rubiaceae)

Bean biochemical composition has been extensively analyzed in Coffea species because of its impact on coffee beverage quality. C. pseudozanguebariae appeared as an interesting wild species because of its low caffeine and chlorogenic acid content, compounds involved in coffee bitterness. Extending the study to its leaves revealed the presence of two unknown phenolic compounds. Isolation, then identification by MS and NMR analysis proved that these compounds are two C-glucosyl-xanthones: mangiferin and isomangiferin. HPLC analyses indicated very high mangiferin content in young leaves. This class of compounds is described for the first time not only in coffee plants but also in the Rubiaceae family. The interest of mangiferin identification in the Coffea genus is discussed.

Structure Determination of 3-O-Caffeoyl-epi-γ-quinide, an Orphan Bitter Lactone in Roasted Coffee

Recent investigations on the bitterness of coffee as well as 5- O-caffeoyl quinic acid roasting mixtures indicated the existence of another, yet unknown, bitter lactone besides the previously identified bitter compounds 5- O-caffeoyl- muco-gamma-quinide, 3- O-caffeoyl-gamma-quinide, 4- O-caffeoyl- muco-gamma-quinide, 5- O-caffeoyl- epi-delta-quinide, and 4- O-caffeoyl-gamma-quinide. In the present study, this orphan bitter lactone was isolated from the reaction products generated by dry heating of 5- O-caffeoylquinic acid model, and its structure was determined as the previously unreported 3- O-caffeoyl- epi-gamma-quinide by means of liquid chromatography-mass spectrometry (LC-MS) and one-/two-dimensional NMR experiments. The occurrence of this bitter lactone, exhibiting a low bitter recognition threshold of 58 micromol/L, in coffee beverages could be confirmed by LC-MS/MS (negative electrospray ionization) operating in the multiple reaction monitoring mode.

Genetic mapping of a caffeoyl-coenzyme A 3-O-methyltransferase gene in coffee trees. Impact on chlorogenic acid content.

Chlorogenic acids (CGA) are involved in the bitterness of coffee due to their decomposition in phenolic compounds during roasting. CGA mainly include caffeoyl-quinic acids (CQA), dicaffeoyl-quinic acids (diCQA) and feruloyl-quinic acids (FQA), while CQA and diCQA constitute CGA sensu stricto (CGA s.s.). In the two cultivated species Coffea canephora and Coffea arabica, CGA s.s. represents 88% and 95% of total CGA, respectively. Among all enzymes involved in CGA biosynthesis, caffeoyl-coenzyme A 3-O-methyltransferase (CCoAOMT) is not directly involved in the CGA s.s. pathway, but rather in an upstream branch leading to FQA through feruloyl-CoA. We describe how a partial cDNA corresponding to a CCoAOMT encoding gene was obtained and sequenced. Specific primers were designed and used for studying polymorphism and locating the corresponding gene on a genetic map obtained from an interspecific backcross between Coffea liberica var. Dewevrei and Coffea pseudozanguebariae. Offspring of this backcross were also evaluated for the chlorogenic acid content in their green beans. A 10% decrease was observed in backcross progenies that possess one C. pseudozanguebariae allele of the CCoAOMT gene. This suggests that CGA s.s. accumulation is dependent on the CCoAMT allele present and consequently on the activity of the encoded isoform, whereby CGA accumulation increases as the isoform activity decreases. Possible implications in coffee breeding are discussed.