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Plant phenolics are powerful antioxidants and free radical scavengers that can contribute to the healthy functional properties of plant-based food and beverages. Thus, dietary behaviours rich in plant-based food and beverages are encouraged. However, it is well-known that the bitter taste and other low-appealing sensory properties that characterize vegetables and some other plant-based foods act as an innate barrier for their acceptance. The aim of this study was to investigate the influence of psychological traits and PROP status (the responsiveness to bitter taste of 6-n- propylthiouracil) on the choice of and familiarity with phenol-rich vegetables and beverages varying in recalled level of bitterness and astringency. Study 1 aimed at assessing the variations of the sensory properties of vegetable and coffee/tea items with two check-all-that-apply (CATA) questionnaires (n = 201 and n = 188 individuals, respectively). Study 2 aimed at investigating how sensitivity to punishment, to reward, and to disgust, food neophobia, private body consciousness, alexithymia, and PROP responsiveness affect choice and familiarity with phenol-rich foods (n = 1200 individuals). A Choice Index was calculated for vegetables (CV) and coffee/tea (CC) as a mean of the choices of the more bitter/astringent option of the pairs and four Familiarity Indices were computed for vegetables (FV) and coffee/tea (FC), higher (+) or lower (-) in bitterness and astringency. Subjects higher in food neophobia, sensitivity to punishment or sensitivity to disgust reported significantly lower choice indices than individuals lower in these traits, meaning that they systematically opted for the least bitter/astringent option within the pairs. Familiarity with vegetables was lower in individuals high in sensitivity to punishment, in food neophobia and in alexithymia, irrespective of their sensory properties. The Familiarity Index with coffee/tea characterized by higher bitterness and astringency was lower in individuals high in food neophobia, sensitivity to disgust, and alexithymia. No significant effect of PROP was found on any indices. The proposed approach based on product grouping according to differences in bitterness and astringency allowed the investigation of the role of individual differences in chemosensory perception and of psychological traits as modulators of phenol-rich foods preference and consumption.

Due to the increase of the use of yeast derivatives (YDs) in winemaking to improve the technological and sensory properties in wines, in this work we evaluated the effect of the post-fermentation application of different yeast derivative products on the physical and chemical properties and astringency of red wines during two consecutive harvests. A commercial and two experimental new yeast derivatives were applied at a medium‒high dosage (30 g/hL). The addition of different yeast derivatives in red wine increased the concentration of different polysaccharide fractions and, therefore, the total polysaccharide content, producing a decrease in the duration of the wine astringency perception over time. The use of yeast derivatives could produce an adsorption/clarification and/or protective effect on the phenolic compounds. However, it did not produce an important modification of the colour parameters. An intensification or a lower decrease of the most volatile compound groups was produced, but it depended on the YDs and yeast strain used in fermentation and post-fermentation processes.

Astringency is often difficult to evaluate accurately in wine because of its complexity. This accuracy can improve through training sessions, but it can be time-consuming and expensive. A way to reduce these costs can be the use of wine experts, who are known to be reliable evaluators. Therefore, the aim of this work was to compare the sensory results and the panel performance obtained using trained panelists versus wine experts (winemakers). Judges evaluated twelve red wines for in-mouth basic perception (sweet, sour, bitter, astringent, and burning sensation) following the same tasting protocol and with the samples being presented in two different tasting modalities. Panels’ performance and relationship between the chemical composition and the sensory perception were investigated. Both panels showed similar consistency and repeatability, and they were able to accurately measure the astringency of the wines. However, the significant correlations between sensory scores and chemical composition varied with the panel and the tasting modality. From our results, we could see that winemakers tended to discriminate better between the samples when the differences were very small.

Wine astringency was evaluated based on the interaction of two complex matrices (red wine and saliva) by combining localized surface plasmon resonance (LSPR) and molecular imprinted polymers (MIP) at gold nanodisks as an alternative to sensorial analysis. The main objective of the work was to simulate wine astringency inside the mouth by mimicking this biological system. The LSPR/MIP sensor provided a linear response for astringency expressed in pentagalloyl glucose (PGG) units in concentrations ranging from 1 to 140 μmol/L. The sensor was also applied to wine samples correlating well with sensorial analysis obtained by a trained panel. The correlation of astringency and wine composition was also evaluated showing that anthocyanins may have an important role, not only for pigmentation but also in astringency. [ABSTRACT FROM AUTHOR]

Astringency, a sensory characteristic of food and beverages rich in polyphenols, mainly results from the formation of complexes between polyphenols and salivary proteins, causing a reduction of the lubricating properties of saliva. To develop an in vitro assay to estimate the astringency of oolong tea infusion, artificial oil bodies were constituted with sesame oil sheltered by a modified caleosin fused with histatin 3, one of the human salivary small peptides. Aggregation of artificial oil bodies was induced when they were mixed with oolong tea infusion or its major polyphenolic compound, (-)-epigallocatechin gallate (EGCG) of 100µM as observed in light microscopy. The aggregated artificial oil bodies gradually floated on top of the solution and formed a visible milky layer whose thickness was in proportion to the concentrations of tea infusion. This assay system was applied to test four different oolong tea infusions with sensory astringency corresponding to their EGCG contents. The result showed that relative astringency of the four tea infusions was correlated to the thickness of floated artificial oil bodies, and could be estimated according to the standard curve generated by simultaneously observing a serial dilution of the tea infusion with the highest astringency. [ABSTRACT FROM AUTHOR]

The effect of the addition of different commercial enological tannins (CETs) on the characteristics of Carménère red wine was evaluated. Initially, chemical characterization of eleven CETs was performed using spectrophotometric and HPLC-DAD techniques. Then, the effects of six CETs on the properties of a Carménère wine during bottle storage (90 days) were evaluated for up to 90 days. Four CETs from wood exhibited highly variable phenolic compositions and the highest values of hydrolyzable tannins and phenolic acids, whereas the CETs from grapes exhibited the highest values of the mono-, oligo- and polymer fractions of flavan-3-ol. The wines enriched with grape CETs presented the highest values of (+)-catechin, (−)-epicatechin, and monomers and polymers of flavan-3-ols, whereas some wines enriched with wood CETs exhibited the highest values of total phenols, total tannins, dihydroflavonols, proanthocyanidin gallates, syringic acid and flavan-3-ol oligomers. Analysis of temporal dominance of sensations revealed no significant differences in the astringency or bitterness perceptions by a trained panel. Altogether, CETs are highly diverse products that can differentially impact the physicochemical and sensorial characteristics of wines to which they are added. Characterization of CETs before their application in winemaking is highly recommended. [ABSTRACT FROM AUTHOR]

Previous studies have investigated mechanisms of the perception of the five basic tastes at the peripheral and neural levels. However, little is known regarding the specific mechanisms and brain activity associated with the perception of astringency. In the present study, we aimed to clarify these mechanisms using functional magnetic resonance imaging (fMRI) in conjunction with taste stimuli, and to investigate the association between subjective appraisal of taste and brain activity. Brain activation to astringency was observed in the insula, superior orbitofrontal cortex, cingulate cortex, and frontal inferior triangularis. In addition, the right ventral anterior insula, which is part of the primary gustatory cortex, showed the strongest blood oxygen level-dependent (BOLD) response to astringent stimuli. Brain activation to bitter and sweet taste was observed in the insula. Each of the three tastes activated a different region of the insula. Also, a subregion in the right anterior insula responded to both astringent and bitter stimuli. Moreover, we observed relationships between the BOLD responsivity during astringent, sweet, and bitter stimuli and the participant’s drinking habits regarding representative beverages of each taste. These results indicate a potential correlation between lifestyle and brain activity with regard to taste perception. [ABSTRACT FROM AUTHOR]

Texture contributes to food acceptance, but oral texture perception is incompletely understood. Presently, we quantified individual sensitivities to lingual tactile roughness and assessed the impact of age, salivary flow (SF), and fungiform papillae density (FPD) on threshold and suprathreshold perception. Additionally, we tested the hypothesis that individuals highly sensitive to tactile roughness exhibit sensitivity to astringent stimuli. Detection thresholds (DTs) were determined using the staircase method for surface roughness from stainless steel coupons (Ra; 0.177-0.465 µm) and astringency elicited by epigallocatechin gallate (EGCG; 0-1.64 mM) and tannic acid (TA; 0-0.71 mM) from 30 individuals. Suprathreshold sensitivity was assessed from intensity ratings of electroforming comparator surfaces with roughnesses ranging from 0.51 to 22.8 µm and astringent stimuli ranging from 0 to 5.2 mM (EGCG) and from 0 to 1.9 mM (TA). SF, FPD, and astringent food pleasantness scores were collected. Variability in threshold roughness sensitivity enabled dividing subjects into high (RHi; n = 16) and low (RLo; n = 14) sensitivity groups; however, no significant differences in age, FPD, or SF were observed across these cohorts. Interestingly, compared with RLo, the RHi group exhibited greater sensitivity to EGCG but not TA astringency and indicated greater pleasantness from astringent foods (e.g., unripe bananas and dark chocolate). When participants were allocated into high (SalivaHi; n = 15) or low SF (SalivaLo; n = 15) groups, TA-evoked astringency thresholds were significantly lower in SalivaHi whom also indicated greater pleasantness from astringent red wines. For suprathreshold assessments of surface roughness or astringency, no significant associations were identified with age, FPD, or SF. Suprathreshold roughness sensitivity was, however, associated with suprathreshold sensitivity to EGCG but not TA astringency. [ABSTRACT FROM AUTHOR]

Higher fungiform papillae density (FPD) has been associated with lower taste sensitivity thresholds and greater perceived taste intensity along with consumption of fewer fruit and vegetables (FV). Children exposed to greater variety of FV tend to habitually consume more FV, however, it is unknown whether exposure effects are attenuated by individual differences in FPD or whether these effects vary according to sensory properties of FV. This study examined the links between children's FPD, current variety of FV consumed, and past experiences with variety of fruit and vegetables. FPD counts were obtained from 61 children between 5 and 9 years old, in schools from affluent areas of Birmingham (UK). Parents completed food frequency questionnaires indicating the variety of FV consumed by children in the last 7 days. Parents also indicated the number of different FV types the children had tasted in their lifetime. FV were subdivided to reflect differences in their sensory properties. The results showed that children with higher FPD who in their lifetime had tasted a greater variety of FV ate a larger variety of FV compared to children with higher FPD, but with lower past exposure. When examining effects within specific subcategories of fruits and vegetables, this pattern held for non-astringent fruit and showed a trend for non-bitter vegetables. Children with lower FPD consumed similar variety of FV irrespective of past experiences with variety of FV. The results suggest that when strong or irritant sensory food properties are not a barrier to intake, higher FPD in the presence of supportive home food environment may be beneficial for FV intake. Individual phenotypic differences may affect responsiveness to environmental factors in children's intake of FV. [ABSTRACT FROM AUTHOR]

Background: The current astringency evaluation for herbs has become dissatisfied with the requirement of pharmaceutical process. It needed a new method to accurately assess astringency. Methods: First, quinine, sucrose, citric acid, sodium chloride, monosodium glutamate, and tannic acid (TA) were analyzed by electronic tongue (e-tongue) to determine the approximate region of astringency in partial least square (PLS) map. Second, different concentrations of TA were detected to define the standard curve of astringency. Meanwhile, coordinate-concentration relationship could be obtained by fitting the PLS abscissa of standard curve and corresponding concentration. Third, Chebulae Fructus (CF), Yuganzi throat tablets (YGZTT), and Sanlejiang oral liquid (SLJOL) were tested to define the region in PLS map. Finally, the astringent intensities of samples were calculated combining with the standard coordinate-concentration relationship and expressed by concentrations of TA. Then, Euclidean distance (Ed) analysis and human sensory test were processed to verify the results. Results: The fitting equation between concentration and abscissa of TA was Y = 0.00498 × e(-X/0.51035) + 0.10905 (r = 0.999). The astringency of 1, 0.1 mg/mL CF was predicted at 0.28, 0.12 mg/mL TA; 2, 0.2 mg/mL YGZTTs was predicted at 0.18, 0.11 mg/mL TA; 0.002, 0.0002 mg/mL SLJOL was predicted at 0.15, 0.10 mg/mL TA. The validation results showed that the predicted astringency of e-tongue was basically consistent to human sensory and was more accuracy than Edanalysis. Conclusion: The study indicated the established method was objective and feasible. It provided a new quantitative method for astringency of herbs. [ABSTRACT FROM AUTHOR]

Background and Aim In a previous study, based on statistical considerations, absorbance values at 230 nm provided a good prediction of wine astringency. The present paper seeks spectroscopic arguments to support such a prediction. Methods and Results Ultraviolet spectra were acquired for several families of phenolic substances, and for the main wine compounds. Wine absorbance at 230 nm is mainly because of tannins which are the major compounds responsible for astringency in wines. Conclusion A good relationship was observed between astringency threshold and absorbance at 230 nm for most of the compounds analysed, confirming the previous results. Moreover, absorbance at 230 nm appeared to balance better the contributions of the different phenolic substances than absorbance at 280 nm. Significance of the Study The spectroscopic observations are in agreement with the statistical considerations. Both studies confirm the value of the absorbance at 230 nm for characterisation of red wine phenolic substances and astringency evaluation. [ABSTRACT FROM AUTHOR]

Background and Aims There is a growing interest in finding alternative wine fining agents to replace potentially allergenic animal-derived and plant-derived proteins. In this context, the potential use of grape-derived fining agents would be beneficial as they would not introduce additional, potentially allergenic products to the finished wine. In this project, grape seed flour, a by-product of the grape oil seed industry, has been used to prepare a grape seed extract (GSE) for testing as a novel wine fining agent. Methods and Results The fining performance of GSE was compared with that of patatin, pea proteins, polyvinylpolypyrrolidone and potassium caseinate in a white and in a rosé wine, and of ovalbumin and gelatin in a red wine. Reduction of turbidity, effect on wine colour, the concentration of phenolic substances, browning potential and wine sensory attributes were determined. Grape seed extract was effective in decreasing white wine turbidity when compared to potassium caseinate. In red wine, GSE removed some anthocyanin and proanthocyanins, while wine colour was only slightly affected. The greatest GSE effect was observed on the sensory properties of the treated wines, as it strongly reduced the vegetal notes in the rosé wine and improved the overall taste of the red wine as a result of the reduction in both acidity and astringency. Conclusions Grape seed extract can be considered a valid allergen-free alternative to the most common wine fining agents. Significance of the Study Grape seed extract is the first effective fining agent endogenous to grapes, thus not attracting the legal restrictions concerning the presence of foreign substances. [ABSTRACT FROM AUTHOR]

Oral tribology is emerging as a new paradigm to quantify friction and lubrication of food-saliva mixtures in the oral mucosa. Recently, oral tribology has captured research attention in quantifying wine astringency, a characteristic ‘dryness feeling’, which strongly impacts consumer preference. Hence, this paper aims to provide a concise review of oral tribology in the context of wine astringency. Firstly, the important roles of ‘biolubricant’ saliva, salivary proteins and current tribo-pairs used in oral tribology measurements are reviewed. Then, we have discussed the key mechanisms of wine astringency involving polyphenol-salivary protein interactions (hydrogen bonding, hydrophobic interactions), rupture of the lubricating salivary film and oral sensation of discrete particles. Studies employing Stribeck curve analysis and microstructural characterisation to understand polyphenol-salivary protein interactions are reviewed. Finally, we highlighted the need for bio-relevant tribo-pairs, simulated oral conditions and tribology-sensory correlation, before such quantification can be used to characterise wine astringency at a commercial level. [ABSTRACT FROM PUBLISHER]

Individual differences in astringency perception are poorly understood. Astringency from tannins stimulates the release of specific classes of salivary proteins. These proteins form complexes with tannins, altering their perceived astringency and reducing their bioavailability. We studied the bitter compound, 6-n-propylthioural (PROP), as a phenotypic marker for variation in astringency perception and salivary protein responses. Seventy-nine subjects classified by PROP taster status rated cranberry juice cocktail (CJC; with added sugar) supplemented with 0, 1.5 or 2.0 g/L tannic acid (TA). Saliva for protein analyses was collected at rest, or after stimulation with TA or cranberry juice (CJ; without added sugar). CJC with 1.5 g/L tannic acid was found to be less astringent, and was liked more by PROP non-taster males than PROP taster males, consistent with the expectation that non-tasters are less sensitive to astringency. Levels of acidic Proline Rich Proteins (aPRPs) and basic Proline Rich Proteins (bPRPs) decreased after TA, while levels of aPRPs, bPRPs and Cystatins unexpectedly rose after CJ. Increases in bPRPs and Cystatins were only observed in PROP tasters. The PROP phenotype plays a gender-specific, but somewhat limited role in the perceived astringency of tannic-acid supplemented, cranberry juice cocktail. The PROP phenotype (regardless of gender) may also be involved in the release of salivary proteins previously implicated in oral health. [ABSTRACT FROM AUTHOR]

To improve the sensory quality of Moroccan red press wines, press wines were separately submitted to micro-oxygenation and three fining agents (gelatin, Polyvinylpolypyrrolidone (PVPP) based formulation and pea protein) treatments at the winery Château Roslane, Morocco. The results showed that each treatment has a distinct behavior in relation with interactions and precipitation monomeric flavan-3-ol and fractions apparent and total condensed tannins. The fining agent corresponding to the vegetable protein has a greater affinity with the fraction of oligomeric condensed tannins with apparent aDP: 3.2. However, gelatin and PVPP based fining agent have an affinity with the catechin and epicatechin as well as with the fraction of polymeric tannins (apparent aDP: 6.6). For the structural parameters of proanthocyanidins, no significant differences were found out in global aDP and percentage of prodelphinidin between the different treatments. The global percentage of galloylation appeared slightly affected, while the global percentage of oxidized proanthocyanidins increased (9%) significantly (P < 0,05) for micro-oxygenation treatment, unlike the fining agent has basic vegetable protein has decreased 36% the percentage of oxidation. For the Saliva Precipitation Index (SPI) and sensory analysis, the greatest reduction of SPI, bitterness and astringency was observed for both basic PVPP and vegetable protein fining agents. [ABSTRACT FROM AUTHOR]

Microencapsulation protects sensitive nutrients, masks flavors, or enhances delivery. Ratios of maltodextrin and γ-cyclodextrin (20:0, 19:1, and 17:3% w/w) were dissolved in water and mixed with pomegranate juice for spray drying with inlet temperatures of 120, 140, and 160°C. The effects on physical properties (water activity, % water content, color, pH, soluble solids (Brix), and methyl cellulose precipitable tannin assay ( MCPTA) were examined. Based on the principle component analysis, formulation influenced color parameters and pH accounted for 46.8% of the variation in the data. Temperature influenced Chroma and water-holding capacity with 31.8% of the variation. The pH of the reconstituted spray-dried powder significantly influenced color. Blending of γ-cyclodextrins to maltodextrins slightly increased the water-holding capacity, increased pH, slightly affected color, and preserved the color over time, slightly better. Increased inlet temperature affected color, decreased water-holding capacity, and decreased astringency index. Small additions of γ-cyclodextrin affect spray-dried powders. [ABSTRACT FROM AUTHOR]

The internal quality of intact persimmon cv. ‘Rojo Brillante’ was assessed trough visible and near infrared hyperspectral imaging. Fruits at three stages of commercial maturity were exposed to different treatments with CO 2 to obtain fruit with different ripeness and level of astringency (soluble tannin content). Spectral and spatial information were used for building classification models to predict ripeness and astringency trough multivariate analysis techniques like linear and quadratic discriminant analysis (LDA and QDA) and support vector machine (SVM). Additionally, flesh firmness was predicted by partial least square regression (PLSR). The full spectrum was used to determine the internal properties and later principal component analysis (PCA) was used to select optimal wavelengths (580, 680 and 1050 nm). The correct classification was above 92% for the three classifiers in the case of ripeness and 95% for QDA in the case of astringency. A value of R 2 = 0.80 and a ratio of prediction deviation (RPD) of 1.86 were obtained with the selected wavelengths for the prediction of firmness which demonstrated the potential of hyperspectral imaging as a non-destructive tool in the assessment of the firmness, ripeness state and astringency level of ‘Rojo Brillante’ persimmon. [ABSTRACT FROM AUTHOR]

The absence of reference materials with defined mouthfeel properties makes it difficult to progress in finding the chemical compound or group of compounds responsible for such properties in complex foods or beverages such as wine. The present work aimed at developing a chemo-sensory strategy providing different odorless fractions with consistent mouthfeel properties. Three wines with different mouthfeel properties were separated in six different odorless fractions per wine by semipreparative liquid chromatography and Solid-Phase Extraction (SPE). Fractions were sensory analyzed by sorting task, repertory grid, triangulation and Rate-All-That-Apply (RATA) with wine experts. In parallel, fractions were chemically characterized by spectrophotometrical strategies, UPLC-MS and MALDI-TOF-MS. A list of 23 terms related to in-mouth properties (18 to mouthfeel) was generated and successfully employed in the description of wines and fractions by RATA analysis. Fractions containing oligomers of flavanols (from tetramers up to decamers) were mainly coarse , grainy , dry on the tongue and dry on the palate . More surprising was the sensory properties of a fraction containing anthocyanin-derivative pigments, which was especially dry , bitter and persistent as was the original wine. This fraction did not contain either oligomers or polymers of flavanols or flavanol-anthocyanin pigments, but a series of trimers of anthocyanins tentatively identified by MALDI-TOF MS. Further separation strategies are being developed to isolate anthocyanin-derived compounds to further confirm their sensory impact in wines. [ABSTRACT FROM AUTHOR]

Commercial inactive dry-yeast based (IDYB) products have been shown to impact positively in different ways on the winemaking process, including sensory enhancement. Despite their relevance little information about physicochemical characteristics of individual IDYB products is available. This study aimed to physicochemically characterize a group of ten commercial IDYB products. Organic, protein and carbohydrate contents by spectrophotometric methods, protein diffusion on cellulose membranes and electrophoretic protein profiles were assessed. Interaction of a IDYB product (CP10) with either salivary protein or a proanthocyanidin-rich extract (binary mixtures) or with both of them (ternary mixtures) was also assessed. Marked physicochemical differences were observed among all ten products. CP10 was found to interact with seed extract and salivary protein. Also, as part of CP10-SE complexes, CP10 interacted with the salivary protein to form ternary complexes. Due to their huge diversity, physicochemical characterization of IDYB products before use in winemaking is recommended. [ABSTRACT FROM AUTHOR]

Cashew apple is a tropical fruit which is an important byproduct of the cashew nut processing industry. It is rich in vitamins, polyphenols, sugars, minerals, amino acids and dietary fibre and can be considered as a functional food. Despite being highly nutritious, utilization of cashew apple has been very limited due to certain disadvantages, such as high perishability and its astringent taste. Various methods have been developed to improve the shelf life and sensory properties of whole cashew apple and its juice. A wide variety of methods ranging from chemical preservatives to high pressure processing have been evaluated for the improvement of shelf life. Physical, bio-chemical, chemical and hybrid methods have also been used to improve organoleptic properties of the juice. However, extensive studies considering the effects of each process on the shelf life and sensory characteristics are still needed. It is also crucial to create awareness and confidence among farmers about cashew apple processing for better economic returns. This paper presents a comprehensive review of various aspects on processing, preservation and value addition to the cashew apple. [ABSTRACT FROM AUTHOR]

BACKGROUND Nowadays supplementing red wines with commercial inactive dry yeasts is a widespread practice in winemaking because it leads to better balanced wines through increased mouthfeel and smooth astringency. The aim of this article is to study, in a red wine and in a model wine solution, how supplementation with three commercial inactive dry yeasts affects chemical composition and astringency. This will give us a better understanding of the action mechanism involved. RESULTS The results suggest that this action mechanism is related to two different phenomena. The first is that inactive yeasts release polysaccharides and oligosaccharides which can increase mouthfeel and inhibit interactions between salivary protein and tannins. The second is that they have a direct effect on the precipitation or absorption of proanthocyanidins, especially the larger polymers, which have been described as the most astringent. CONCLUSION It can be concluded that supplementation with inactive yeasts is indeed a useful tool for smoothing the astringency of red wines. © 2016 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The presence of phenolic compounds can make a great contribution to the perception of astringency in red wines based on their interactions with proteins. Human salivary protein and bovine serum albumin were used in this study to investigate the relationship between astringency and polyphenol composition. The interactions between polyphenols and proteins were analysed by means of electrophoresis and fluorescence spectra, and they were further confirmed by sensory analysis. The results indicate that a positive correlation existed among the percentage of polymeric proanthocyanidins and the total phenols. Additionally, astringent wine was generally identified as having a high percentage of polymeric fragments. In comparison with other fractions, polymeric fractions exhibited the highest affinity for protein, and thus the highest astringency. [ABSTRACT FROM AUTHOR]

In this study, we prepared chitin nanofibers (CNFs) of varying diameter and added sodium chloride (NaCl) to CNF solutions. We performed ultrasonication on the CNFs for 30, 45, and 60 min, following which, the CNFs (i.e., CNF30, CNF45, CNF60) displayed a diameter of 9.3, 5.6, and 5.1 nm, respectively; the diameter decreased with the ultrasonication time. The zeta potential of CNFs with various concentrations and diameters ranged from 21.8 to 37.3 mV. The kinematic viscosities of the CNFs were affected with the CNF concentrations and addition of NaCl. When 0.15 and 0.30 g/L CNF solutions were added 3.0 g/L NaCl, they tasted saltier than the 3.0 g/L NaCl solution, but less astringent compared with the CNF solutions without NaCl. The saltiness enhancement of CNF60 was superior to that of the CNF30 and CNF45 due to CNF60 was smaller diameter and less intertwined. The NH 3 + of CNF bound Cl − by electrostatic interactions that causing the ratio of free Na + in the diffuse layer increased and then improving the saltiness and decreasing the astringency of the solutions. Therefore, application of CNFs in food is promising. [ABSTRACT FROM AUTHOR]

This study was conducted to identify key components that attenuate oral fat sensations in oolong tea. Oolong tea is often consumed with fatty food because of its "refreshing" effects during the course of a meal. We hypothesized that oolong tea gives a cleanness sensation via psychological and physical effects. We showed through a sensory study that oolong tea consumption significantly reduces oral fat sensations as compared to water. Interfacial tension was measured to evaluate the emulsifying properties of teas and its components. Oolong tea and tea-leaf saponins were significantly lower when compared with other teas and major tea components. Furthermore, the emulsion made from tea-leaf saponins and corn oil was stable after 24 h. Moreover, polyphenol enhanced oolong tea showed significantly decreased oral fattiness when compared with oolong tea. Thus, tea-leaf saponins appear to be key components in reducing oral fat sensation. [ABSTRACT FROM AUTHOR]

The fermentation of herbaceous peony black tea by enzyme is beneficial to improve the flavor quality. This work aimed to investigate the influence of withering and fermentation on the taste and aroma of herbaceous peony black tea by combining physical and chemical analysis, sensory evaluation, LC-QQQ and GC-QTOF. Physicochemical analysis and sensory evaluation determined that a withering degree of 30, fermentation time of 4 h and fermentation temperature of 28 °C improved the quality of herbaceous peony black tea. Moreover, LC-QQQ combined with sensory evaluation results showed that polyphenols (gallic acid and methyl gallate, catechin, (-)-epicatechin gallate, and naringenin) and monoterpenes (paeoniflorin and albiflorin) were significantly correlated with the astringency of herbaceous peony black tea (P < 0.05) and that fermentation could effectively reduce the astringency of herbaceous peony black tea. GC-QTOF combined with OPLS-DA (VIP > 1) identified 28 volatile components as key herbaceous peony black tea compounds. Compared with unfermented tea, the volatile components and contents were significantly increased by fermentation, and phenylethyl alcohol, 5-methylfurfural, cuminaldehyde, 1-(furan-2-yl) ethanone and o-cymene were formed. This study provides a theoretical basis and technical guidance for the comprehensive utilization and green development of herbaceous peony petal tea. [Display omitted] • Withering and fermentation can improve the quality of herbaceous peony black tea. • Polyphenols and monoterpenes are the main astringent components. • 28 volatile components are the key compounds of herbaceous peony black tea. • Fermentation can significantly improve tea aroma and reduce astringency. [ABSTRACT FROM AUTHOR]

• A modified carbonic maceration technique (MCM) was applied to make wines at industrial scale. • MCM used destemmed but uncrushed grapes for maceration and fermentation in contact with skins. • MCM wines had lower C 6 alcohols, but higher acetates. • MCM significantly increased the fruity aroma of wines. • MCM increased anthocyanin concentration, resulting in greater color intensity. The objective of this study was to investigate the effect of modified carbonic maceration technique (MCM) on the chemical and sensory characteristics of 'Cabernet Sauvignon' wines at an industrial production scale. Wines made from MCM and cold maceration technique (COM, control) were analyzed chemically and sensorially. Wines made by MCM demonstrated higher L* and a* values but lower b* values, and higher anthocyanin concentrations, which indicated that MCM wines had a greater color intensity, more reddish and bluish hues compared to COM wines. MCM wines contained more flavonols but lower flavan-3-ols. MCM treatment reduced the concentration of C 6 alcohols and some higher alcohols, and increased the concentration of esters, especially acetates. Moreover, sensory evaluation showed the MCM treatment increased the overall aroma intensity, due to the increase of black fruit and fresh fruit notes and the decrease of green note. In addition, MCM wines had lower astringency and persistence. [ABSTRACT FROM AUTHOR]

Formulating whey protein beverages at acidic pH provides better clarity but the beverages typically develop an unpleasant and astringent flavor. Our aim was to evaluate the application of infrared spectroscopy and chemometrics in predicting astringency of acidic whey protein beverages. Whey protein isolate (WPI), whey protein concentrate (WPC), and whey protein hydrolysate (WPH) from different manufacturers were used to formulate beverages at pH ranging from 2.2 to 3.9. Trained panelists using the spectrum method of descriptive analysis tested the beverages providing astringency scores. A portable Fourier transform infrared spectroscopy attenuated total reflectance spectrometer was used for spectra collection that was analyzed by multivariate regression analysis (partial least squares regression) to build calibration models with the sensory astringency scores. Beverage astringency scores fluctuated from 1.9 to 5.2 units and were explained by pH, protein type (WPC, WPI, or WPH), source (manufacturer), and their interactions, revealing the complexity of astringency development in acidic whey protein beverages. The WPC and WPH beverages showed an increase in astringency as the pH of the solution was lowered, but no relationship was found for WPI beverages. The partial least squares regression analysis showed strong relationship between the reference astringency scores and the infrared predicted values (correlation coefficient >0.94), giving standard error of cross-validation ranging from 0.08 to 0.12 units, depending on whey protein type. Major absorption bands explaining astringency scores were associated with carboxylic groups and amide regions of proteins. The portable infrared technique allowed rapid prediction of astringency of acidic whey protein beverages, providing the industry a novel tool for monitoring sensory characteristics of whey-containing beverages. [ABSTRACT FROM AUTHOR]

The absorber is known to be vertical axisymmetric for a single-point wave energy converter (WEC). The shape of the wetted surface usually has a great influence on the absorber's hydrodynamic characteristics which are closely linked with the wave power conversion ability. For complex wetted surface, the hydrodynamic coefficients have been predicted traditionally by hydrodynamic software based on the BEM. However, for a systematic study of various parameters and geometries, they are too multifarious to generate so many models and data grids. This paper examines a semi-analytical method of decomposing the complex axisymmetric boundary into several ring-shaped and stepped surfaces based on the boundary discretization method (BDM) which overcomes the previous difficulties. In such case, by using the linear wave theory based on eigenfunction expansion matching method, the expressions of velocity potential in each domain, the added mass, radiation damping and wave excitation forces of the oscillating absorbers are obtained. The good astringency of the hydrodynamic coefficients and wave forces are obtained for various geometries when the discrete number reaches a certain value. The captured wave power for a same given draught and displacement for various geometries are calculated and compared. Numerical results show that the geometrical shape has great effect on the wave conversion performance of the absorber. For absorbers with the same outer radius and draught or displacement, the cylindrical type shows fantastic wave energy conversion ability at some given frequencies, while in the random sea wave, the parabolic and conical ones have better stabilization and applicability in wave power conversion. [ABSTRACT FROM AUTHOR]

Wine tasting results in interactions of tannin-ethanol solutions with proteins and lipids of the oral cavity. Among the various feelings perceived during tasting, astringency and bitterness most probably result in binding events with saliva proteins, lipids and receptors. In this work, we monitored the conjugated effect of the grape polyphenol catechin and ethanol on lipid membranes mimicking the different degrees of keratinization of oral cavity surfaces by varying the amount of cholesterol present in membranes. Both catechin and ethanol fluidify the membranes as evidenced by solid-state 2 H NMR of perdeuterated lipids. The effect is however depending on the cholesterol proportion and may be very important and cumulative in the absence of cholesterol or presence of 18 mol % cholesterol. For 40 mol % cholesterol, mimicking highly keratinized membranes, both ethanol and catechin can no longer affect membrane dynamics. These observations can be accounted for by phase diagrams of lipid-cholesterol mixtures and the role played by membrane defects for insertion of tannins and ethanol when several phases coexist. These findings suggest that the behavior of oral membranes in contact with wine should be different depending of their cholesterol content. Astringency and bitterness could be then affected; the former because of a potential competition between the tannin-lipid and the tannin-saliva protein interaction, and the latter because of a possible fluidity modification of membranes containing taste receptors. The lipids that have been up to now weakly considered in oenology may be become a new actor in the issue of wine tasting. [ABSTRACT FROM AUTHOR]

Ellagitannins and aromatic compounds evolution in Cabernet Sauvignon wines macerated in oak barrels for a year was studied. Identical barrels with different toastings (medium toasting, medium toasting with watering, Noisette) were used in French, Italian and USA cellars. Ellagitannins increased by 84–96% with aging time, as did woody volatiles, by 86–91% in French wines and 23–35% in Italian wines, while fruity aroma compounds declined by 50–57% in the French and Italian wines over a 12-months period. Nevertheless, other behaviors and different kinetics rates for these compounds were observed depending on barrel toasting, wine matrix and their interactions. Perceived overall woody intensity was closely related to trans -whiskey lactone, guaiacol and vanillin, whereas astringency and bitterness were significantly linked to ellagitannins ( p < 0.05). This is the first study that evaluates the toasting effect on wines from different countries matured in the same oak barrels. [ABSTRACT FROM AUTHOR]

Avaliaram-se os efeitos dos tratamentos com CO2 e 1-MCP (1-metilciclopropeno) sobre a adstringência (índice de tanino), firmeza da polpa e distúrbios da epiderme em caqui 'Rama Forte'. Frutos foram tratados com 1-MCP por 24 h, logo após a colheita e/ou com alto CO2 (70%) por 24 ou 48 h, um dia após a colheita ou após o armazenamento refrigerado (AR). Os caquis foram armazenados sob atmosfera modificada a 0 ºC, por 45 dias, e a seguir mantidos a 23 ºC, por 9 dias. Frutos-controle (não tratados com 1-MCP nem com CO2) amoleceram em três dias e perderam aproximadamente 50% da adstringência em 6 dias após o AR. A exposição ao CO2 acelerou a redução da adstringência. Esse efeito do CO2 foi menor em frutos tratados com 1-MCP, especialmente quando o CO2 foi aplicado após o AR, por apenas 24 h. O tratamento com 1-MCP inibiu o amolecimento e a redução da adstringência, especialmente nos frutos não tratados com CO2. O amolecimento de frutos tratados com 1-MCP foi maior quando a exposição ao CO2 ocorreu antes do AR. A combinação dos tratamentos com 1-MCP e alto CO2 reduziu a incidência de podridões e manchas translúcidas, mas não alterou o desenvolvimento de pintas pretas ('estrias'). Os resultados indicam que é possível induzir perda da adstringência sem excessiva perda da firmeza da polpa de caquis 'Rama Forte' após o AR pela associação dos tratamentos com 1-MCP logo após a colheita e alto CO2 após o AR.This study evaluated the effects of CO2 and 1-MCP (1-methylcyclopropene) treatments on astringency (tannin index), flesh firmness and skin disorders on 'Rama Forte' persimmon. Fruit were treated with 1-MCP for 24 h right after harvest and/or with high CO2 (70% CO2 balanced with air) for 24 or 48 h, one day after harvest or after cold storage (CS). Fruit were stored in modified atmosphere for 45 days at 0ºC and then held at 23ºC for 9 days. Control fruit (untreated with neither 1-MCP nor CO2) softened in 3 days and lost about 50% of astringency in 6 days after CS. The high CO2 exposure enhanced the reduction of astringency. This CO2 effect was lesser on 1-MCP treated fruit, especially when high CO2 was applied after CS, for only 24 h. 1-MCP treatment inhibited fruit softening and the reduction of astringency, especially on fruit not treated with CO2. The softening of 1-MCP treated fruit was greater when the CO2 treatment was applied before CS. The combination of high CO2 and 1-MCP treatments reduced incidence of rots and translucent stains, but did not affect the development of dark 'groove like' skin disorders. The results indicate that it is possible to induce astringency loss without substantial loss of firmness of 'Rama Forte' persimmon by the combination of treatments with 1-MCP right after harvest and high CO2 after cold storage.

Astringency is an important characteristic of red wine quality. The sensation is generally thought to be produced by the interaction of wine tannins with salivary proteins and the subsequent aggregation and precipitation of protein-tannin complexes. The importance of wine astringency for marketability has led to a wealth of research on the causes of astringency and how tannins impact the quality of the sensation, particularly with respect to tannin structure. Ultimately, the understanding of how tannin structure impacts astringency will allow the controlled manipulation of tannins via such methods as micro-oxygenation or fining to improve the quality of wines.