Sensory-guided Fractionation Research Articles

Characterization of key bitter compounds in Idesia polycarpa var. vestita Diels fruit by sensory-guided fractionation

Idesia polycarpa var. vestita Diels (I. vestita) has become a promising oil crop due to its easily digestible and highly nutritious fruit oil. However, the intense bitter taste of its fruit greatly limits its development and promotion in the food industry. Herein, five key bitter compounds from I. vestita fruit were isolated by sensory-guided fractionation and characterized using ultra-high performance liquid chromatography-quadrupole time of flight-mass spectrometer and nuclear magnetic resonance. The bitter taste of the identified compounds was subsequently validated by threshold tests and computational molecular docking. The bitterness threshold in water of idesin was the lowest (12.051 mg/L), and all bitter substances spontaneously bound to the bitter receptors hTAS2R16 and hTAS2R14, with a stronger affinity for the latter (approximately −6.5 – −9.0 kcal/mol). This is the first systematic study of bitter compounds in I. vestita fruit, providing a scientific basis for revealing the mechanism of bitterness formation and bitterness control.

Characterization of the impact of chlorogenic acids on tactile perception in coffee through an inverse effect on mouthcoating sensation

Coffee “body” is acknowledged by coffee industry professionals to be an attribute which contributes meaningfully to overall coffee quality and is defined as the collective tactile sensation imparted by the beverage. Currently, there is limited knowledge of the chemical compounds that contribute to tactile attributes in coffee. In the present work, coffee body was determined to be comprised of 4 sub-attributes including mouthcoating, astringency, chalkiness, and thickness and the specific constituents contributing to the tactile sensation of mouthcoating were further pursued using sensory-guided fractionation via preparative-scale liquid chromatography. Signal detection-based sensory methodologies were employed to characterize the sensory effects elicited by selected compounds in water and coffee matrices. Two chlorogenic acids, 3-O-caffeoylquinic acid (3-CQA) and 4-O-caffeoylquinic acid (4-CQA), were observed to impart subtle but significantly perceptible mouthcoating effects in water and/or coffee. Counterintuitively, sensory perception was inversely related to compound concentration. Complex receptor-ligand interactions or salivary lubrication dynamics are discussed as two potential mechanisms to explain this inverse relationship. Taken together, the outcomes of the present study (1) provide new targets for coffee tactile sensation optimization and modulation, (2) identify a novel dimension of sensory impact for two compounds of the chlorogenic acid family, and (3) present a need for deeper investigation into 3-CQA and 4-CQA mechanisms of sensation.

Discovery and Identification of Tastants and Taste-Modulating N-Acyl Amino Acid Derivatives in Traditional Korean Fermented Dish Kimchi Using a Sensomics Approach.

Sensory-guided fractionation by means of ultrafiltration and gel permeation chromatography followed by high-performance liquid chromatography, synthesis, liquid chromatography-tandem mass spectrometry (LC-MS/MS) quantitation, and taste re-engineering experiments revealed taste-active and taste-enhancing compounds contributing to the umami, mouthful and complex taste profile of the fermented Korean dish, kimchi. Besides basic taste-active compounds, in particular, various N-acylated amino acids deriving from succinic acid and lactic acid imparted taste-modulating properties in food matrices. Taste threshold concentrations were determined to evaluate intrinsic and modulating effects. Quantitation of N-acylated amino acids in kimchi following synthesis revealed the presence of numerous derivatives showing taste-active properties. Sensory evaluation including recombination and partial addition experiments highlighted that both the N-lactoyl- and the N-succinoyl amino acid derivatives contribute to increasing the fullness, volume, and complexity of food matrices, whereas the latter directly contributes to the overall taste of kimchi in natural concentrations.

Evaluation of bitter compounds in Zanthoxylum schinifolium Sieb. et Zucc. by instrumental and sensory analyses

As a common food seasoning in China, Zanthoxylum schinifolium Sieb. et Zucc. is desired by consumers for its special aroma; however, its bitter taste has a negative economic impact on the food industry. In this study, untargeted metabolomics was used to perform full-coverage detection of metabolites in Z. schinifolium Sieb. et Zucc. A total of 53 potential bitter metabolites were screened. Additionally, key bitter compounds were concentrated using sensory-guided fractionation technique and subsequently characterized by UPLC-Q-TOF-MS, and a total of 13 bitter compounds were obtained. Then, dose over threshold values (DOT) of these 13 compounds were calculated, showing that 11 compounds significantly contribute to the bitterness of Z. schinifolium Sieb. et Zucc., with quercetin, isorhamnetin and kaempferol have particularly low thresholds and high contents. This study is the first to comprehensively define the bitter substances in Z. schinifolium Sieb. et Zucc., providing a reliable theoretical basis for future research on bitterness mechanisms.

Exploring the Mystery of the Sweetness of Baijiu by Sensory Evaluation, Compositional Analysis and Multivariate Data Analysis.

Sweetness is an important Baijiu quality marker, but there is limited research on it. In this study, the main contributors to Baijiu sweetness were identified by “sensomics” combined with “flavoromics”. A total of 43 volatile compounds (mostly esters) were found that appeared to contribute to Baijiu sweetness, through sensory-guided fractionation and compositional analysis. Correlation analysis between the volatile composition and perceived sweetness of 18 Baijiu samples with different sweet intensities identified 14 potential contributors. Additional testing verified that combining the 14 compounds reproduced Baijiu sweetness exactly, and omission testing identified ethyl hexanoate, hexyl hexanoate and ethyl 3-methylbutanoate as the major contributors to Baijiu sweetness. These findings not only broadened our understanding of Baijiu sweetness, but also highlighted the major contribution of volatile compounds to sweetness perception, knowledge which may facilitate future flavor modification of a wide variety of foods and beverages.

Comprehensive identification of non-volatile bitter-tasting compounds in Zanthoxylum bungeanum Maxim. by untargeted metabolomics combined with sensory-guided fractionation technique

Zanthoxylum Bungeanum Maxim. is an important seasoning in Chinese cooking, but its bitter taste limits its use by some consumers. In this study, metabolomic analysis based on ultra-high-performance liquid chromatograph–tandem mass spectrometry (UPLC–MS) was used to screen out a vast number of potential non-volatile bitter compounds in Z. bungeanum. Results showed that there were 37 potential bitter compounds in Z. bungeanum, and possible mechanisms underlying its bitter taste were provided. Further, instrumental analyses combined with sensory evaluation were used to identify the key bitter compounds in Gou jiao, a wild variant of Z. Bungeanum with a strong bitter taste. Totally 15 key bitter compounds were identified, most of which have a low bitterness recognition threshold. This study is the first comprehensive identification of non-volatile bitter compounds in Z. bungeanum and provides a basis for future investigations into mitigating bitterness and uncovering how the interaction between different bitter compounds affects taste.

The umami intensity enhancement of peanut protein isolate hydrolysate and its derived factions and peptides by Maillard reaction and the analysis of peptide (EP) Maillard products

This study aimed to examine the feasibility of improving umami taste of peanut protein isolate hydrolysate (PPIH) and its fractions (obtained via ethanol precipitation and gel filtration chromatography) and peptide constituents, through their reactions with glucose at 98 °C for 70 min (Maillard reaction). To get insights into the characteristics of the peptide contributors with high umami intensity and/or umami-enhancing activity, Maillard reaction-guided and sensory-guided fractionation and characterization using ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) and eXpose algorithm calculation method were subsequently involved. Three umami and umami-enhancing peptides, three umami-enhancing peptides with other tastes, three bitter peptides and one astringent peptide were found. For the first time, peptide TP was reported to suppress umami intensity of monosodium glutamate (MSG) aqueous solution. Combined treatments of enzymatic hydrolysis and Maillard reaction on PPI facilitated umami enhancement. Maillard products of identified peptides had higher umami intensities and/or greater umami-enhancing abilities. Pyroglutamylproline (pyroEP) and glucosylated EP were discovered as the major compounds of EP Maillard product.

The behavior of umami components in thermally treated yeast extract

Umami proteolytics are natural food flavor alternatives to glutamate. In this study, key umami taste fractions were separated and purified from thermally treated yeast extract (YE) to yield fifteen umami peptides. Systematic approaches using sensory-guided fractionation on taste-active umami proteolytics separation and detection were utilized. A reaction temperature of 110 °C was optimum for umami peptide generation. Under this reaction temperature, the sensory score and E-tongue results of umami taste were the highest. The sensory evaluation-based taste dilution analysis and taste threshold determination supported the hypothesis that umami peptides have their physiological effect by binding to G-protein coupled receptors. The structural differences of umami peptides contribute to their taste profile and allow categorization into two group Types. Fifteen umami peptides were then categorized into Type I and Type II regarding the contractual-based taste mechanism: Type I peptides imparted complex tastes. The tastes of Type I peptides could split into two stages: bitterness and umami in pure water, whereas, Type II peptides presented strong umami taste at a high concentration in pure water, and the relationship between umami capacity and peptides concentration was linear. Finally, the guidance of the umami peptide usage in the flavor industry has been established according to broths dissolution test.

Identification of bitter compounds in extruded corn puffed products

Differences in the taste profile of corn puffed products formulated with refined versus whole grain mix flour were characterized. The perceived bitter intensity was reported to be the main taste difference between the samples. Based on multidimensional sensory-guided fractionation techniques and subsequent identification by MS and NMR analysis, the primary bitter compounds identified in the whole grain sample were l-tryptophan, chaenorpine, N1,N5-Di-[E]-p-coumaroyl-spermidine, and terrestribisamide. All compounds were reported to contribute to bitterness perception at the concentrations reported in the saliva after mastication of the extruded products; chaenorphine had the highest contribution to the perceived bitterness. All bitter compounds were endogenous products of the corn.

Analysis of Umami Taste Compounds in a Fermented Corn Sauce by Means of Sensory-Guided Fractionation.

Corn sauce, an ingredient obtained from the fermentation of enzymatically hydrolyzed corn starch and used in culinary applications to provide savory taste, was investigated in this study. The links between its sensory properties and taste compounds were assessed using a combination of analytical and sensory approaches. The analyses revealed that glutamic acid, sodium chloride, and acetic acid were the most abundant compounds, but they could not explain entirely the savory taste. The addition of other compounds, found at subthreshold concentrations (alanine, glutamyl peptides, and one Amadori compound), contributed partly to close the sensory gap between the re-engineered sample and the original product. Further chemical breakdown, by a sensory-guided fractionation approach, led to the isolation of two fractions with taste-modulating effects. Analyses by mass spectrometry and nuclear magnetic resonance showed that the fractions contained glutamyl peptides, pyroglutamic acid, glutamic acid, valine, N-formyl-glutamic acid, and N-acetyl-glutamine.

Sensomics-Based Molecularization of the Taste of Pot-au-Feu, a Traditional Meat/Vegetable Broth.

Targeted quantification of 49 basic taste-active molecules, followed by the calculation of dose-over-threshold (DoT) factors, and taste re-engineering experiments revealed minerals, nucleotides/nucleosides, amino acids, organic acids, and carbohydrates as the key compounds of Pot-au-Feu, a traditional broth preparation from beef cuts and vegetables. Moreover, the dipeptide carnosine was identified to be the key inducer for the white-meaty and thick-sour orosensation of the broth, next to anserine and 1-deoxy-d-fructosyl-N-β-alanyl-l-histidine, the latter of which has been identified for the first time by means of a sensory-guided fractionation. Sensory studies revealed the threshold concentration of carnosine in model broth to decrease by a factor of 5 upon nonenzymatic glycosylation to reach 4.4 mmol/L for its Amadori product 1-deoxy-d-fructosyl-N-β-alanyl-l-histidine.

Isolation and characterization of key contributors to the "kokumi" taste in soybean seeds.

The water extract of soybean seeds (Glycine max (L.) Merr.) is nearly tasteless, but "kokumi" taste sensation was confirmed upon addition of a basic umami solution containing glutamic acid, inosine monophosphate, and sodium chloride. To identify the key contributors to the "kokumi" taste sensation in soybean seeds, sensory-guided fractionation, taste sensory analyses, and LC-MS/MS analyses were utilized. γ-glutamyl-tyrosine and γ-glutamyl-phenylalanine were identified as contributors to "kokumi taste"; specifically, these γ-glutamyl peptides imparted the "kokumi" taste sensation at a low taste threshold in a basic umami solution. Raffinose and stachyose, which are sufficiently present in soybean seeds, exhibited a synergistic effect in regard to the enhanced "kokumi" taste sensation of γ-glutamyl peptides. This is the first report that the combined use of γ-glutamyl peptides and oligosaccharides can increase the "kokumi" intensity, which suggests that soybean extracts or soymilk can be used to enhance the "kokumi" taste sensation in food products.

Structure-Pungency Relationships and TRP Channel Activation of Drimane Sesquiterpenes in Tasmanian Pepper (Tasmannia lanceolata).

Sensory-guided fractionation of extracts of Tasmanian pepper berries revealed 20 drimane sesquiterpens, among which polygodial, warburganal, and 1β-acetoxy-9-deoxy-isomuzigadial exhibited the lowest pungency threshold concentrations on the tongue surface (0.6-2.8 nmol/cm2) and elicited a dose-dependent calcium influx into mTRPA1 expressing CHO cells with the lowest EC50 values (4.5 ± 1.0 to 16.7 ± 7.5 μmol/L) and a good correlation to oral pungency thresholds (R2 = 0.986, linear regression). Calcium imaging assays demonstrated these chemosensates to induce a calcium influx into cultured trigeminal neurons prepared from wildtype (TRPA1+/+) mice, whereas no calcium influx was observed in neurons from TRPA1 knockout mice (TRPA1-/-), thus confirming the α,β-unsaturated 1,4-dialdehyde structure to be the required structural motif for a low oral puncency thresholds and activation of the Transient Receptor Potential Channel A1 (TRPA1). Time-resolved NMR experiments confirmed the pungency mediating mechanism for electrophilic drimane sesquiterpene dialdehydes to be different from that found for other electrophilic pungent agents like isothiocyanates, which have been shown to undergo a covalent binding with cysteine residues in TRPA1. Instead, the high-impact chemosensates polygodial, warburganal, and 1β-acetoxy-9-deoxy-isomuzigadial showed immediate reactivity with the ε-amino group of lysine side chains to give pyrrole-type conjugates, thus showing evidence for TRPA1 activation by covalent lysine modification.

Identification of bitter compounds from dried fruit of Ziziphus jujuba cv. Junzao

ABSTRACTBitterness in dried jujube fruit can adversely influence its palatability and consumer acceptability. In the present investigation, sensory-guided fractionation with techniques of liquid–liquid extraction, macroporous resin separation, and LC-MS/QTof was applied to identify the bitter compounds in dried jujube fruit (Z. jujuba cv. junzao). The results showed that bitter substances can be successfully extracted from dried jujube fruit using ethanol followed by n-butanol solution. The extract could then be further separated into five fractions by utilizing the macroporous resin separation technique. From this, three bitter fractions were obtained where 35 compounds, including 7 nitrogen compounds, 14 flavonoids, 12 saponins, and 2 fatty acid oxides，were tentatively identified. Based on the structures of these compounds, bitterness generation is likely to result from endogenous phytochemicals of jujube fruit and Maillard reactions during drying processing and also storage.

New Sweet-Tasting Oleanane-Type Triterpenoid Saponins from "Tugancao" (Derris eriocarpa How).

With the aim to investigate the sweet-tasting compounds in Derris eriocarpa How (a substitute for licorice in "Zhuang" and "Dai" ethnopharmacy in Guangxi and Yunnan provinces of China) as well as to ascertain why the stem of D. eriocarpa can be used to substitute for licorice in the sweetness taste aspect, taste sensory-guided fractionation was conducted to isolate sweet constituents from the extract of D. eriocarpa. Four sweet-tasting triterpenoid saponins were obtained, including millettiasaponin A (1) and three new saponins named derrisaponins A-C (2-4). The sweetness potency was evaluated by a human sensory panel test. The sweetness intensities of compounds 1-4 were determined to be approximately 150, 80, 2, and 0.5 times relative to sucrose at the concentration of 1%, respectively, of which compounds 1 and 2, with a free carboxyl group at the C-30 position, showed more potent sweetness intensity. In addition, compounds 1 and 2 showed no acute toxic activity at doses of 250 and 400 mg/kg of body weight, respectively, assessed through caudal vein injection to ICR mice. The contents of the sweetest compounds in stems were analyzed quantitatively as 352.80 mg/kg for compound 1 and 1887.60 mg/kg for compound 2 performed by ultra-performance liquid chromatography-tandem mass spectrometry.

New Sweet-Tasting C21-Pregnane Glycosides from Pericarps of Myriopteron extensum.

Ten novel C21 pregnane glycosides, extensumside C-L (1-10), were isolated as highly sweet-tasting substances from the edible pericarps of Myriopteron extensum (Wight) K. Schum by sensory-guided fractionation and purification. Their structures were determined through 1D and 2D NMR, such as HSQC, HMBC, 1H-1H COSY, HSQC-TOCSY, and ROESY, as well as other spectroscopic analysis combined with chemical evidence. These compounds shared the same aglycone, 3β,16α-dihydroxy-pregn-5-en-20-one, and contained the deoxysugar chain and the glucose chain which were linked to C-3 and C-16 of the aglycone, respectively. The sweetness potency was evaluated by a human sensory panel test and preliminary structure-taste relationship was discussed. The sweetness intensities of these compounds are between 50 and 400 times greater than that of sucrose. Furthermore, quantitation analyses of compounds 1, 3, 4, and 6 in different parts of M. extensum indicated that the concentrations of these sweet components in the pericarps are obviously higher than those in stems and roots.

Fragrant Sesquiterpene Ketones as Trace Constituents in Frankincense Volatile Oil of Boswellia sacra

In a previous study, two highly potent yet unidentified odorants were detected that were present at trace levels in the volatile fraction of Boswellia sacra gum resin. These two compounds were isolated semipreparatively from the volatile oil by a sensory-guided fractionation process involving microscale bulb-to-bulb distillation, countercurrent chromatography, and preparative gas chromatography. In this manner, the two oxygenated sesquiterpenes could be identified as rotundone (1) and mustakone (2). Compound 2 is described for the first time as a potent odorant with a very low odor threshold.

Sequence, taste and umami-enhancing effect of the peptides separated from soy sauce

Five tasty peptides were separated from soy sauce, by sensory-guided fractionation, using macroporous resin, medium-pressure liquid chromatography and reverse phase-high performance liquid chromatography, and identified by ultra-performance liquid chromatography tandem mass-spectrometry as ALPEEV, LPEEV, AQALQAQA, EQQQQ and EAGIQ (which originated from glycinin A1bB2-445, glycinin A1bB2-445, cobyric acid synthase, leucine-tRNA ligase and glycoprotein glucosyltransferase, respectively). LPEEV, AQALQAQA and EQQQQ tasted umami with threshold values of 0.43, 1.25 and 0.76mmol/l, respectively. ALPEEV and EAGIQ had minimal umami taste, but ALPEEV, EAGIQ and LPEEV showed umami-enhancement with a threshold estimated at 1.52, 1.94 and 3.41mmol/l, respectively. In addition, the synthetic peptides showed much better sensory taste than mixtures of their constitutive amino acids. It indicated that peptides might play an important role in the umami taste of soy sauce.

Sensomics-Assisted Elucidation of the Tastant Code of Cooked Crustaceans and Taste Reconstruction Experiments.

Sensory-guided fractionation by means of ultrafiltration and cation-exchange chromatography, followed by MS/MS quantitation, and taste re-engineering experiments revealed the key taste molecules coining the characteristic taste profile of the cooked meat of king prawns. Furthermore, quantitative analysis demonstrated that the taste differences between crustaceans are due to quantitative differences in the combinatorial code of tastants, rather than to qualitative differences in the tastant composition. Besides the amino acids glycine, L-proline, and L-alanine, the characteristic seafood-like sweet profile was found to be due to the sweet modulatory action of quaternary ammonium compounds, among which betaine, homarine, stachydrin, and trimethylamine-N-oxide were found as the key contributors on the basis of dose-activity considerations. Knowledge of this combinatorial tastant code provides the foundation for the development of more sophisticated crustacean flavors that are lacking any heavy metal ions and allergenic proteins present when using crustacean extracts for food flavoring.

Mozambioside Is an Arabica-Specific Bitter-Tasting Furokaurane Glucoside in Coffee Beans.

Sensory-guided fractionation of a roasted coffee beverage revealed a highly polar, bitter-tasting subfraction, from which the furokaurane glucoside mozambioside was isolated and identified in its chemical structure by means of HDMS and NMR spectra. Sensory evaluation revealed a bitter taste recognition threshold of 60 (± 10) μmol/L. UPLC-HDMS quantitation of raw coffee beans showed that Arabica coffees contained 396-1188 nmol/g mozambioside, whereas only traces (<5 nmol/g) were detected in Robusta coffees, thus suggesting that mozambioside can be used as an analytical marker for Arabica coffee. Roasted Arabica contained a substantially reduced concentration (232 ± 37 nmol/g), indicating partial degradation of mozambioside during coffee roasting. Mozambioside was nearly quantitatively extracted into the aqueous brew during coffee-making (86-98%).