A look upon the adsorption of different astringent agents to oral models: Understanding the contribution of alternative mechanisms in astringency.

Salivary proteins precipitation by interaction with polyphenols is the major mechanism for astringency. However, alternative mechanisms seem involved in the perception of different subqualities of astringency. In this study, adsorption of four astringent agents to in vitro oral models and their sensory properties were assessed. Overall, green tea infusion and tannic acid have shown a higher adsorption potential for models with oral cells and absence of saliva. Alum and grape seed extract presented higher adsorption in models with presence of oral cells and saliva. Multiple factor analysis suggested that adsorption may represent important mechanisms to elicit the astringency of alum. Models including saliva, were closely associated with overall astringency and aggressive subquality. Models with cells and absent saliva were closely associated with greenness, suggesting a taste receptor mechanism involvement in the perception. For the first time a correlation between an oral-cell based assay and astringency sensory perception was shown.

Unveiling the Immunomodulatory Potential of Phenolic Compounds in Food Allergies.

Food allergies are becoming ever more prevalent around the world. This pathology is characterized by the breakdown of oral tolerance to ingested food allergens, resulting in allergic reactions in subsequent exposures. Due to the possible severity of the symptoms associated with this pathology, new approaches to prevent it and reduce associated symptoms are of utmost importance. In this framework, dietary phenolic compounds appear as a tool with a not fully explored potential. Some phenolic compounds have been pointed to with the ability to modulate food allergies and possibly reduce their symptoms. These compounds can modulate food allergies through many different mechanisms, such as altering the bioaccessibility and bioavailability of potentially immunogenic peptides, by modulating the human immune system and by modulating the composition of the human microbiome that resides in the oral cavity and the gastrointestinal tract. This review deepens the state-of-the-art of the modulation of these mechanisms by phenolic compounds. While this review shows clear evidence that dietary supplementation with foods rich in phenolic compounds might constitute a new approach to the management of food allergies, it also highlights the need for further research to delve into the mechanisms of action of these compounds and decipher systematic structure/activity relationships.

Characterization of the Effect of a Novel Production Technique for 'Not from Concentrate' Pear and Apple Juices on the Composition of Phenolic Compounds.

The consumption of 'not-from-concentrate' (NFC) fruit juices can be a convenient and enjoyable way to incorporate the nutritional benefits and flavors of fruits into one's diet. This study will focus on the effect of production of juices from apple and pear fruits, by using centrifugal decanter and tangential filtration, on the profile of polyphenols as a valuable source of bioactive compounds. Likewise, by-products from the juice industry were characterized in order to understand the high-value-added potential based on their composition of polyphenols. Briefly, apple and apple juice showed great contents of chlorogenic acid (0.990 ± 0.021 mg/g of DW), the dihydrochalcone phloridzin (1.041 ± 0.062 mg/g of DW), procyanidins (0.733 ± 0.121 mg/g of DW) and quercetin derivatives (1.501 ± 0.192 mg/g of DW). Likewise, the most abundant compounds in pear and pear juices were chlorogenic acid (0.917 ± 0.021 mg/g of DW), caffeoylquinic acid (0.180 ± 0.029 mg/g of DW), procyanidins (0.255 ± 0.016 mg/g of DW) and quercetin derivatives (0.181 ± 0.004 mg/g of DW). Both temperature and tangential speed affect the amount of phenolic compounds in fruit juices, highlighting the need to control the technological process to obtain a more nutritious/healthier beverage. Overall, NFC juices arise as a better option when compared with concentrated juices. Furthermore, the higher yield of phenolic compounds found in fruit pomace clearly open new ways for upcycling this fruit by-product as a high-value-added ingredient.

Lycopene from Red Guava (Psidium guajava L.): From Hepatoprotective Effect to Its Use as Promising Self-Emulsifying Drug Delivery System for Anti-Inflammatory and Antioxidant Applications.

Lycopene is a carotenoid with potential use in the treatment of chronic illnesses. Here, different formulations of lycopene were studied: lycopene-rich extract from red guava (LEG), purified lycopene from red guava (LPG) and a self-emulsifying drug delivery system loaded with LPG (nanoLPG). The effects of administering orally various doses of LEG to hypercholesterolemic hamsters were evaluated regarding the liver function of the animals. The cytotoxicity of LPG in Vero cells was analyzed by a crystal violet assay and by fluorescence microscopy. In addition, nanoLPG was employed in stability tests. LPG and nanoLPG were tested for their cytotoxic effect on human keratinocytes and antioxidant capacity on cells in an endothelial dysfunction model in an isolated rat aorta. Finally, the effect of different nanoLPG concentrations on the expression of immune-related genes (IL-10, TNF-α, COX-2 and IFN-γ) from peripheral blood mononuclear cells (PBMC) using real-time PCR was also analyzed. Results suggest that LEG, despite not being able to improve blood markers indicative of liver function in hypercholesterolemic hamsters, reduced hepatic degenerative changes. Additionally, LPG did not show cytotoxicity in Vero cells. In relation to nanoLPG, the effects produced by heat stress evaluated by Dynamics Light Scattering (DLS) and visually were loss of color, texture change and phase separation after 15 days without interfering with the droplet size, so the formulation proved to be efficient in stabilizing the encapsulated lycopene. Although LPG and nanoLPG showed moderate toxicity to keratinocytes, which may be related to cell lineage characteristics, both revealed potent antioxidant activity. LPG and nanoLPG showed vasoprotective effects in aortic preparations. The gene expression assay indicates that, although no significant differences were observed in the expression of IL-10 and TNF-α, the PBMCs treated with nanoLPG showed a reduction in transcriptional levels of IFN-γ and an increased expression of COX-2. Thus, the work adds evidence to the safety of the use of lycopene by humans and shows that tested formulations, mainly nanoLPG due to its stability, stand out as promising and biosafe products for the treatment of diseases that have oxidative stress and inflammation in their etiopathology.

Interactions between Beer Compounds and Human Salivary Proteins: Insights toward Astringency and Bitterness Perception.

Beer is one of the most consumed beverages worldwide with unique organoleptic properties. Bitterness and astringency are well-known key features and, when perceived with high intensity, could lead to beer rejection. Most studies on beer astringency and bitterness use sensory assays and fail to study the molecular events that occur inside the oral cavity responsible for those perceptions. This work focused on deepening this knowledge based on the interaction of salivary proteins (SP) and beer phenolic compounds (PCs) and their effect toward these two sensory attributes. The astringency and bitterness of four different beers were assessed by a sensory panel and were coupled to the study of the SP changes and PC profile characterization of beers. The human SP content was measured before (basal) and after each beer intake using HPLC analysis. The beers' PC content and profile were determined using Folin-Ciocalteu and LC-MS spectrometry, respectively. The results revealed a positive correlation between PCs and astringency and bitterness and a negative correlation between SP changes and these taste modalities. Overall, the results revealed that beers with higher PC content (AAL and IPA) are more astringent and bitter than beers with a lower PC content (HL and SBO). The correlation results suggested that an increase in whole SP content, under stimulation, should decrease astringency and bitterness perception. No correlation was found between the changes in specific families of SP and astringency and bitterness perception.

Study of Serial Exposures of an Astringent Green Tea Flavonoid Extract with Oral Cell-Based Models.

It is well known that repeated exposure to phenolic compounds (PCs) raises astringency perception. However, the link between this increase and the oral cavity's interactions with salivary proteins (SPs) and other oral constituents is unknown. To delve deeper into this connection, a flavonoid-rich green tea extract was tested in a series of exposures to two oral cell-based models using a tongue cell line (HSC3) and a buccal mucosa cell line (TR146). Serial exposures show cumulative PC binding to all oral models at all concentrations of the green tea extract; however, the contribution for the first and second exposures varies. The tongue mucosal pellicle (HSC3-Mu-SP) may contribute more to first-stage astringency (retaining 0.15 ± 0.01 mg mL-1 PCs at the first exposure), whereas the buccal mucosal pellicle (TR146-Mu-SP) retained significantly less (0.08 ± 0.02 mg mL-1). Additionally, increased salivary volume (SV+), which simulates the stimulation of salivary flow brought by a food stimulus, significantly enhances PC binding, particularly for TR146 cells: TR46-Mu-SP_SV+ bound significantly higher total PC concentration (0.17 ± 0.02 mg mL-1) than the model without increased salivary volume TR146-Mu-SP_SV- (0.09 ± 0.03 mg mL-1). This could be associated with a higher contribution of these oral cells for astringency perception during repeated exposures. Furthermore, PCs adsorbed in the first exposure to cell monolayer models (+TR146 and +HSC3) change the profile of PCs bound to these models in the second exposure. Regarding the structure binding activity, PCs with a total higher number of hydroxyl groups were more bound by the models containing SP. Regarding the SP, basic proline-rich proteins (bPRPs) may be involved in the increased perception of astringency upon repeated exposures. The extent of bPRP precipitation by PCs in mucosal pellicle models for both cell lines (HSC3 and TR146) in the second exposure (76 ± 13 and 83 ± 6%, respectively) was significantly higher than in the first one (25 ± 14 and 5 ± 6%, respectively).

Mechanics and Energetic Analysis of Rowing with Big Blades with Randall Foils.

Empirical observations support that the addition of a plastic strip - also known as Randall foils - on the top edge of a rowing blade improves rowing efficiency during the cycle propulsive phase. The aim of the current study was to analyze the effect of using big blades with and without Randall foils on rowing performance. Twenty experienced rowers performed two 90 s tethered rowing bouts (with and without Randall foils) to assess their impact on force production and physiologic variables. All tests were randomized and a repeated measure design was used to compare experimental conditions. Higher values of peak and mean peak forces (479.4±134.7 vs. 423.2±153.0, d=0.83 and 376.5±101.4 vs. 337.1±113.3 N, d=0.68), peak oxygen uptake (47.9±7.5 vs. 45.3±7.3 mL∙kg-1∙min-1, d=0.19), peak blood lactate concentration (7.9±1.6 vs. 6.9±1.7 mmol∙L-1, d=0.16), blood lactate increasing speed (0.08±0.01 vs. 0.07±0.06 [(mmol·L-1)·s-1], d=0.27) and lactic anaerobic energy (27.4±7.9 vs. 23.4±8.1 kJ, d=0.23) were found for big blades with vs. without Randall foils, p<0.05. The current data suggest that the Randall foils can positively affect rowing performance.

Antitumoral potential of Chartergellus-CP1 peptide from Chartergellus communis wasp venom in two different breast cancer cell lines (HR+ and triple-negative).

Breast cancer represents the most incident cancer in women. Surgery, chemotherapy, radiation therapy, and hormone therapy remain the main treatment for this type of cancer. However, increasing resistance to anti-cancer drugs through poor response for some types of breast cancer to treatments highlights the need to develop new therapeutic agents to fight the disease. In this study, we evaluated the anti-tumor potential of the Chartergellus-CP1 peptide isolated from the wasp venom of Chartergellus communis in human breast cancer cell lines MCF-7 (HR+) and MDA-MB-231 (triple-negative). Cells viability, morphology, cell cycle dynamics, reactive oxygen species (ROS) production, and apoptosis were assessed for both cell lines after exposure to Chartergellus-CP1 during 24 and 48 h. The results showed that Chartergellus-CP1 led to a significant increase of cells in the S phase in addition to a high generation of ROS (being more evident in the MCF-7 cell line) associated with apoptotic cell death. This work demonstrates, for the first time, the cytotoxic effects of Chatergellus-CP1 on human breast cancer cell lines including cell cycle profile, oxidative stress generation, and cell death mechanisms.

Wine astringent compounds monitored by an electrochemical biosensor.

An innovative approach for monitoring astringent polyphenols in beverages (wines) is described, consisting of an electrochemical biosensor constructed by adsorbing salivary α-amylase or proline-rich protein (PRP) onto amined gold screen-printed electrodes. Interaction with polyphenols was tested using pentagalloyl glucose (PGG) as a standard, an important representative element for astringency. The analytical properties of the resulting biosensors were evaluated by electrochemical impedance spectroscopy at different pHs. The PRP-biosensor was able to bind to PGG with higher sensitivity, displaying lower limit of the linear range of 0.6 µM. Wine samples were tested to prove the concept and the concentrations obtained ranged from 0.17 to 4.7 µM, as expressed in PGG units. The effects of side-compounds on PRP and on α-amylase binding to PGG were tested (gallic acid, catechin, ethanol, glucose, fructose and glycerol) and considered negligible. Overall, concentrations > 1.0 µM in PGG units are signaling electrochemical impedance, providing a quantitative monitoring of astringent compounds.

Intra- and inter-cycle velocity variations in sprint front crawl swimming.

Intra- and inter-cycle velocity variations are of utmost importance for achieving enhanced swimming performances. However, intra-cycle events can impact and interfere with the subsequent cycles, making relevant to study several consecutive cycles allowing a better understanding of this possibility. We have assessed front crawl intra- and inter-cyclic velocity variations and overall biomechanical variables in sprint front crawl swimming. Twenty-seven elite swimmers performed 25 m all-out front crawl, were videotaped using moving cameras placed at the sagittal plane and were grouped according to their sprint mean velocity. Coefficient of variation, root mean square error and mean velocity differences between two consecutive paired cycles allowed assessing intra- and inter-cycle velocity variations. Visual inspection was performed to analyse possible variability causes and independent-measures t-test allowed comparing groups. Sprint front crawl was characterised by intra- (11.12 ± 2.98) and inter-cycle velocity variation (2.27 ± 0.80 of inter-cycle velocity coefficient of variation and 0.031 ± 0.014 of root mean square error), with no differences between fastest and slowest swimmers. Front crawl intra-cycle velocity variation was not related to mean velocity and cycle sequence but considered swimmers' personal strategy. Despite some abnormal oscillations within cycles, inter-cycle velocity variation was not caused by intra-cycle velocity variation, mean velocity or cycle sequence.

SCS 4th Annual Conference: Strength and Conditioning for Human Performance, Porto, Portugal, 2021.

On behalf of the Strength & Conditioning Society (SCS) and the Faculty of Sport of the University of Porto, we are pleased to present the abstracts of the SCS 4th Annual Conference: Strength and Conditioning for Human Performance, which took place in, Porto, Portugal, on 12-13 November 2021. The event was a success with invited sessions from renowned international and national speakers on a myriad of topics related to strength and conditioning and its application to health and sports performance, such as agility training and testing, high-intensity interval training in chronic conditions, hamstring strain injuries in soccer, and the utilization of surface electromyography (EMG) decomposition for assessing human performance, among others. During the Conference there were also different practical workshops on (1) velocity-based training; (2) performance testing and athlete monitoring using force platforms; (3) 3D kinematics tracking and flow force assessment in aquatic sports; (4) the application of inertial sensors for physical performance testing; (5) muscle fiber recruitment, force production, and energy expenditure in progressive bicycle testing; (6) EMG decomposition, motor-units recruitment, and muscle contraction modes; and (7) recovery strategies in team-sport athletes. Researchers and academics were able to present their latest findings by submitting the abstracts that compose this Conference Report.

New insights into the oral interactions of different families of phenolic compounds: Deepening the astringency mouthfeels.

Astringency is a tactile sensation of puckering, tightening and dryness in the oral cavity, commonly induced by polyphenols. In this study, the interaction of two phenolic compound mixtures, one rich in gallotannins and the other in flavonols, with two oral models (tongue (HSC3) or buccal mucosa (TR146) was evaluated. Results provided evidence that gallotannins and flavonols seem to bind in a different way to the different oral constituents and models used. Gallotannins seems to bind more to the tongue than to the buccal mucosa cell line, but this difference is overcome by the presence of salivary proteins. Conversely, for the flavonol mixture, the presence of salivary proteins seems to restrain the interaction with oral cell lines. Structure-binding activity relationships were evidenced within each mixture: for gallotannins, interactions seem to increase along with the galloylation degree while for flavonol it was observed that increasing numbers of glucose residues decreased the binding activity.

Interaction between salivary proteins and cork phenolic compounds able to migrate to wine model solutions.

This work reports the study of the interaction of human salivary proteins (SP) with phenolic compounds that migrate from cork stoppers to wine. This study yields valuable data to understand the influence that these compounds may have on the sensory perception of wine from an astringency perspective. For that, three cork fractions containing the phenolic compounds that migrate in greater amounts from cork to model wine solutions were selected. Fraction M1 contains gallic acid, protocatechuic acid, vanillin and protocatechuic aldehyde; fraction M2 comprises essentially gallic acid and ellagic acid, as well as castalagin and dehydrocastalagin; and fraction M3 contains the two isomeric ellagitannins castalagin and vescalagin. The reactivity of each fraction towards SP was M3 > M2 > M1. Within M3 fraction, castalagin showed a higher ability to precipitate SP (mainly aPRPs, statherin and P-B peptide) comparatively to vescalagin. In M1 fraction, caffeic and sinapic acids were the compounds with the highest interaction with SP, mainly cystatins. In addition, there also seems to be a matrix effect (presence of other compounds) that could be affecting these interactions.

Understanding the molecular interactions between a yeast protein extract and phenolic compounds.

Phenolic compounds are partially removed during fining, which may influence the organoleptic properties of beverages. Among phenolic compounds, tannins have been widely associated to the taste of beverages (namely astringency and bitterness). Furthermore, phenolic acids and anthocyanins may also influence bitterness and the latter are also responsible for beverages' color. Thus, it is necessary to perform molecular studies to better understand the effect of fining agents in the overall phenolic composition of beverages and the resulting organoleptic changes. The molecular interactions between these three classes of phenolic compounds and a yeast protein extract (YPE), designed as a new fining agent, was studied. The binding affinities were assessed by fluorescence quenching at two temperatures (21 °C and 37 °C) and in two reaction media (water and wine model solution). The size of aggregates formed was characterized by Dynamic Light Scattering and the selectivity of protein interaction was analyzed by electrophoresis. Overall, pentagalloylglucoside (tannin) showed the highest binding affinity for YPE, followed by malvidin 3-glucoside (anthocyanin), p-coumaric acid (phenolic acid) and gallic acid (phenolic acid). The studied temperatures and solvents affected the interaction affinities as well as the aggregates' size. Binding selectivity of proteins from YPE was not found. These results open new perspectives to control the fining process by using the YPE as a fining agent taking into account the further effect in the organoleptic properties of beverages.

Young Swimmers' Middle-Distance Performance Variation within a Training Season.

The current study aimed to longitudinally evaluate anthropometric, physiological, and biomechanical variables related to middle-distance performance during a 45-week swimming training season. Thirty-four swimmers (age: 12.07 ± 1.14 years) performed a maximum of 400 m front crawl at the beginning (T1) and finish of the first macrocycle (T2, 15 weeks) and the finish of the second (T3, 18 weeks) and third macrocycles (T4, 12 weeks). Time-related variables, stroke rate (SR), stroke length (SL), and stroke index (SI) were recorded during the test, and blood lactate ([La]) and glucose ([Glu]) concentrations were measured post-exercise. The time of the 400 m effort decreased after each macrocycle (T2 vs. T1, 7.8 ± 5.6%; T3 vs. T2, 3.7 ± 3.1%; T4 vs. T3, 3.8 ± 3.4%; p < 0.01). Four hundred meter speed changes between T1 and T2 were positively related to variations in [La], [Glu], SL, and SI (r = 0.36-0.60, p < 0.05). Changes between T2 and T3 were related to SI only (r = 0.5, p < 0.05), and modifications between T3 and T4 were associated with SL and SI variations (r = 0.34 and 0.65, p < 0.05). These results indicate that a well-structured year plan including three macrocycles leads to a significant age-group swimming performance improvement, mostly connected with an increase in technical proficiency.

Do swimmers conform to criterion speed during pace-controlled swimming in a 25-m pool using a visual light pacer?

The purpose of this study was to investigate whether swimmers follow the instructed speed (vtarget) accurately with the aid of a commercial visual light pacer during front crawl and backstroke swimming in a 25 m pool. Ten male swimmers performed 50 m front crawl and backstroke at different speeds (controlled by a visual light pacer) in a 25 m pool. The mean speed during the 50 m swimming (vS) was quantified from the time measured by a stopwatch. The mean speed of the centre of mass during a stroke cycle in the middle of the pool (vCOM) was calculated from three-dimensional coordinates obtained from Direct Linear Transformation of two-dimensional digitised coordinates of 19 segment endpoints for each of six cameras. Swimmers achieved accurate vS in front crawl and backstroke (ICC = 0.972 and 0.978, respectively). However, vCOM for the single mid-pool sample had lower correlations with vtarget (ICC = 0.781 and 0.681, respectively). In backstroke, vCOM was slower by 4.1-5.1% than vtarget. However, this was not the case in front crawl (1.0-2.7%). With the use of a visual light pacer, swimmers can achieve accurate mean speed overall but are less able to achieve the target speed stroke by stroke.

Interactions between polyphenol oxidation products and salivary proteins: Specific affinity of CQA dehydrodimers with cystatins and P-B peptide.

Throughout the apple juice and cider making process, polyphenols undergo enzymatic oxidation which generates a great variety of polyphenol oxidation products. Since 5'-O-Caffeoylquinic acid (CQA) is one of the major phenolic compounds and the preferential substrate for polyphenoloxidase in apple juice, its oxidation leads to the formation of newly formed molecules by which dehydrodimers (MW 706 Da) are included. Interactions of salivary proteins (SP) with native polyphenols is a well-known phenomenon, but their interactions with polyphenol oxidation products has not been studied yet. In this work, we decided to decipher the interactions between CQA dehydrodimers and SP (gPRPs, aPRPs, statherins/P-B peptide, and cystatins) using HPLC-UV and fluorescence. These results showed that contrary to what was expected, CQA dehydrodimers presented a low interaction with PRPs, but revealed a specific interaction with statherins/P-B peptide and cystatins. This work settles for the first time the interactions between SP and polyphenol oxidation products.

Polyphenolic Characterization of Nebbiolo Red Wines and Their Interaction with Salivary Proteins.

The present study correlates the polyphenolic composition of two different Nebbiolo red wines from the 2015 vintage (M and P), with the salivary proteins' precipitation process. The work centered on the polyphenolic characterization of Nebbiolo wines and their interaction with different families of salivary proteins. Overall, both wines were found to be very reactive with human saliva which was supposed to contribute to their astringent character. The comparison of both wines showed that the M wine presented higher values of total phenolics, total proanthocyanidins, and tannin specific activity. Moreover, this wine showed a higher interaction with salivary proteins. Altogether, the chemical characterization and reactivity toward human saliva could contribute to the wine astringency.

Interaction of a Procyanidin Mixture with Human Saliva and the Variations of Salivary Protein Profiles over a 1-Year Period.

Procyanidins are widely associated with astringency perception and promptly interact/precipitate salivary proteins (SPs). In this work, the SP profile of 17 volunteers was monitored for 1 year, focusing on the SP families most related to astringency [aPRPs (acidic proline-rich proteins), bPRPs (basic proline-rich proteins), gPRPs (glycosylated proline-rich proteins), cystatins, P-B peptide, and statherin]. Although the total SP content remained constant, bPRPs showed high variability. Saliva from 5 volunteers was selected, each individual's saliva presenting a prominence in one of the referred SP families; each was used to interact with grape seed procyanidin oligomeric fraction. Independent of the prominences, a total depletion in statherin and P-B peptide was observed. These subjects performed a sensory assay and the limit of detection for astringency was determined. Overall, the specificity of SP toward procyanidins seemed to be more important in the interactions than the total SP content. The highest reactivity toward SPs was observed for epicatechin gallate, procyanidin dimers B7, B2g, and trimer C1.

Bioactive Peptides and Dietary Polyphenols: Two Sides of the Same Coin.

The call for health-promoting nutraceuticals and functional foods containing bioactive compounds is growing. Among the great diversity of functional phytochemicals, polyphenols and, more recently, bioactive peptides have stood out as functional compounds. The amount of an ingested nutrient able to reach the bloodstream and exert the biological activity is a critical factor, and is affected by several factors, such as food components and food processing. This can lead to unclaimed interactions and/or reactions between bioactive compounds, which is particularly important for these bioactive compounds, since some polyphenols are widely known for their ability to interact and/or precipitate proteins/peptides. This review focuses on this important topic, addressing how these interactions could affect molecules digestion, absorption, metabolism and (biological)function. At the end, it is evidenced that further research is needed to understand the true effect of polyphenol-bioactive peptide interactions on overall health outcomes.