Monomeric Flavanols Research Articles

Associations Between Flavonoid Intake and Subclinical Atherosclerosis: The MESA.

Flavonoids may play a role in mitigating atherosclerotic cardiovascular diseases, with evidence suggesting effects may differ between vascular beds. Studies examining associations with subclinical markers of atherosclerosis between subpopulations with different underlying risks of atherosclerosis are lacking. Among 5599 participants from the MESA (Multi-Ethnic Study of Atherosclerosis), associations between dietary flavonoid intakes (estimated from a food frequency questionnaire) and subclinical measures of atherosclerosis (ankle-brachial index, carotid plaques and intima-media thickness, and coronary artery calcification) were examined using repeated measures models. Exposures and outcomes were measured at exam 1 (2000-2002) and exam 5 (2010-2011). Stratified analyses and interaction terms were used to explore effect modification by time, sex, race/ethnicity, and smoking status. In the analytic population, at baseline, ≈46% were males with a median age of 62 (interquartile range, 53-70) years and total flavonoid intakes of 182 (interquartile range, 98-308) mg/d. After multivariable adjustments, participants with the highest (quartile 4) versus lowest (quartile 1) total flavonoid intakes had 26% lower odds of having an ankle-brachial index <1 (odds ratio, 0.74 [95% CI, 0.60-0.92]) and 18% lower odds of having a carotid plaque (odds ratio, 0.82 [95% CI, 0.69-0.99]), averaged over exams 1 and 5. Moderate (quartile 3) to high (quartile 4) intakes of flavonols, flavanol monomers, and anthocyanins were associated with 19% to 34% lower odds of having an ankle-brachial index <1 and 18% to 20% lower odds of having carotid plaque. Participants with the highest intakes of anthocyanins (quartile 4) at baseline had a marginally slower rate of carotid plaque progression than those with moderate intakes (quartiles 2 and 3). There were no significant associations with intima-media thickness or coronary artery calcification. Observed associations did not differ by sex, race/ethnicity, or smoking status. In this multi-ethnic population, higher dietary flavonoid intakes were associated with lower odds of peripheral and carotid artery atherosclerosis. Increasing intakes of healthy, flavonoid-rich foods may protect against atherosclerosis in the peripheral and carotid arteries.

Flavonoid intakes, chronic obstructive pulmonary disease, adult asthma, and lung function: a cohort study in the UK Biobank

BackgroundGiven their antioxidative stress, anti-allergic, anti-inflammatory, and immune-modulating effects, flavonoids are hypothesized to play a role in preventing chronic obstructive pulmonary disease (COPD) and asthma. ObjectivesThis cohort study aimed to examine associations between flavonoid intake and COPD, asthma, and lung function. MethodsAmong 119,466 participants of the UK Biobank, median [interquartile range] age of 60 [53, 65] y, we estimated intakes of flavonoids, flavonoid-rich foods, and a flavodiet score from 24-h diet assessments. Prospective associations with both incident COPD and asthma and cross-sectional associations with measures of lung function [%predicted forced expiratory volume in 1s (FEV1); and FEV1/forced vital capacity (FVC)] were examined using multivariable-adjusted Cox proportional hazards and linear regression models, respectively. We investigated mediation by inflammation––represented by the INFLA score––and stratified analyses by smoking status. ResultsCompared with low intakes, moderate intakes of total flavonoids, flavonols, theaflavins + thearubigins, and flavanones, and moderate-to-high intakes of flavanol monomers, proanthocyanidins, anthocyanins, flavones, and the flavodiet score were associated with up to an 18% lower risk of incident COPD {e.g., [hazard ratio (95% confidence interval) for total flavonoids: 0.83 (0.75, 0.92)]} but not incident asthma. Furthermore, compared with low intakes, higher intakes of all flavonoid subclasses (except theaflavins + thearubigins), and the flavodiet score were associated with better percent predicted FEV1 baseline. Associations were most apparent in ever (current or former) smokers. Flavonoid intakes were inversely associated with the INFLA score, which appeared to mediate 11%–14% of the association between intakes of proanthocyanidins and flavones and incident COPD. ConclusionsModerate-to-high flavonoid intakes were associated with a lower risk of COPD and better lung function, particularly among ever smokers. Promoting intakes of healthy flavonoid-rich foods, namely, tea, apples, and berries, may improve respiratory health and lower COPD risk, particularly in individuals with a smoking history.

Chemical Characterization of Sauvignon Blanc Wines from Three Cold-Climate-Growing Areas of Chile.

The influence of the geographical location on the chemical composition of commercial Sauvignon Blanc wines was investigated. The assay was carried out on Sauvignon Blanc wines from three cold-climate valleys in Central Chile, Casablanca, Leyda, and San Antonio. The analyses revealed clear variations in some chemical parameters, especially in titratable acidity, which was higher in the geographical areas closest to the Pacific Ocean, such as the Leyda and San Antonio valleys. Regarding the composition of low-molecular-weight phenolic compounds, 17 compounds were found, and the results show that the Casablanca valley exhibits a greater abundance of monomeric flavanols, such as (+)-catechin, whereas the Leyda valley shows a higher abundance in flavonols and phenolic acids esterified with tartaric acid. Concerning the aromatic compound profile, the wines from the Casablanca valley showed a greater abundance of esters, C13 norisoprenoids, and some terpenes. The PLS-DA analysis revealed some differences, especially between wines from Casablanca and Leyda, demonstrating that the difference in the chemical composition of the wines was influenced by the geographical area.

Hydration and Fortification of Common Bean (Phaseolus vulgaris L.) with Grape Skin Phenolics-Effects of Ultrasound Application and Heating.

Ultrasound (US)-assisted soaking combined with fortification with red grape skin (GS) phenolics was applied on two Phaseolus varieties, namely White Kidney Bean (WKB) and Cranberry Bean (CB), before heat treatment. The aims were to investigate: (a) the effect of US application on the kinetic of hydration; (b) the extent of absorption of different phenolic classes of GS into the beans and the resulting effect on antioxidant activity; (c) the effects of heat treatment on the phenolic fraction and antioxidant activity of GS extract- and water-soaked beans. US fastened the soaking step of both WKB and CB beans, which showed the sigmoidal and the downward concave shape hydration curves, respectively. Anthocyanins, flavonols, flavanol and phenolic acids levels increased with GS soaking, but US application was effective only for increasing the level of flavonols, while it favored the loss of endogenous phenolic acids and it did not affect the uptake of anthocyanins and flavanols. Heat treatment decreased the levels of most of phenolic compounds, but increased the levels of monomeric flavanols. Overall, the antioxidant activity was 40% higher in WKB and 53% higher in CB upon GS-fortification than in the control beans, despite the effects of heating. This fortification strategy could be applied for value addition of varieties low in phenolics or as a pre-treatment before intensive processing.

An Overview of Pharmacological Activities and Beneficial Effects of 3‐Hydroxyflavone

AbstractFlavonoids are a diverse group of naturally occurring plant compounds that are primarily composed of phenols in their free form or glycosides. Flavonoid medicines are primarily composed of 2‐phenyl‐g‐benzopyrone. This family consists of monomeric flavanols, flavanones, anthocyanidins, flavones, isoflavonoids, and flavonols. The study's main objective is to review the newly discovered natural flavones and flavanols, as well as the biological and pharmacological actions of these essential flavonoids. As per the available data, 3‐hydroxy flavone plays a vital role in the prevention of a range of diseases. Research studies have confirmed that 3‐hydroxyflavone has a broad range of pharmacological properties like therapeutic effects against pain, inflammation, oxidative stress; hepatotoxicity, hypertension, ulcerogenesis, allergy, platelet dysfunction, microbes, fungi, viruses, rhinovirus, malaria, and carcinogens. 3‐Hydroxy flavone has limited utility because of their poor solubility and bioavailability. This has led to the search for new drug delivery methods, such as nanoparticles. To get over these problems, it would be preferable to administer 3‐hydroxyflavone via the biocompatible nanoparticles. It is expected that nanoparticles will improve the solubility of 3‐hydroxyflavone, enhance its therapeutic properties and facilitate its transport to the brain.

Upcycling flavanol-rich Chardonnay and Pinot noir grape thinned clusters as potentially functional food ingredients in cocoa-based products.

In California, over 3.4 million tons of wine grapes were crushed in 2020 while every year roughly 20% of the grape mass goes unused. Grape cluster thinning at veraison, a common agricultural practice to ensure color homogeneity in wine grapes, adds to the production costs and generates substantial on-farm loss during grapevine cultivation in which the health-promoting values of thinned clusters (unripe grapes) are usually overlooked. In particular, the health-promoting properties of flavanol monomers, specifically (+)-catechin and (-)-epicatechin, and their oligomeric procyanidins, have been extensively studied in cocoa and chocolate but not so much in grape thinned clusters in recent epidemiology studies. As part of the important agricultural by-products upcycling effort, the current study compared thinned clusters from Chardonnay and Pinot noir, two premium wine grape varieties cultivated in California, to a traditionally Dutch (alkalized) cocoa powder that has been widely used in food applications. Thinned cluster fractions from Chardonnay and Pinot noir grapes grown in the North Coast of California showed much higher concentrations of flavanol monomers and procyanidins, with 208.8-763.5 times more (+)-catechin, 3.4-19.4 times more (-)-epicatechin, and 3.8-12.3 times more procyanidins (by degree of polymerization DP 1-7) than those in the traditionally Dutch cocoa powder. These flavanol-rich thinned clusters that are also considered as plant-based natural products suggested great potential to be functional ingredients in cocoa-based products-which have been ubiquitously perceived as flavanol-rich products by consumers-to enhance their overall dietary flavanol content.

Patterns of polyphenol intake and risk of depressive symptomatology in a population-based cohort of older adults

Current evidence suggests that some isolated polyphenols (PP) may exert promising effects for the risk of depression in young adults, however studies among older adults remain limited. The aim of the current study was to examine the prospective association between patterns of PP intake and the risk of depressive symptomatology (DS) in older adults. The study sample was based on the Three-City (3C) Bordeaux cohort of adults aged 65 years and over and without DS at the time of recruitment. The intakes of PP, summarised into 21PP classes, were determined using a 24-h recall combined with the Phenol-Explorer database. In addition, the patterns of PP intake were identified by a Principal Component Analysis (PCA). DS was evaluated using the Center for Epidemiologic Studies Depression Scale (CES-D) over a period of 15 years with a reassessment every 2-3 years. The incident DS was reported for CES-D score ≥16 and/or the use of antidepressant treatment. The association between the patterns of PP intake at baseline and the risk of DS was computed using multivariate random-effect logistic regression models. Among the 1074 participants (mean age 75.7y, SD 4.8y), 423 (39.4%) developed a DS during the follow-up. Distinct patterns of PP intake were identified, explaining up to 50% of the variance. The two first patterns, mainly driven by stilbenes and dihydroflavonols and by hydroxyicnnamic acid and alkylmethoxyphenols respectively, were not associated with the odds of DS. Furthermore, a higher score on the third pattern, mainly driven by monomeric flavanols and theaflavins, was associated with a significant 27% lower risk of DS over time (Odd Ratio=0.73, 95% Confidence Interval [0.55; 0.97]). This prospective study suggested that a pattern high in monomeric flavanols and theaflavins intakes, mainly provided by tea, was associated with a reduced risk of DS in older adults. These results provide promising evidence on combined PP intakes that would require further confirmation in other samples.

Influence of Grape Cell Wall Polysaccharides on the Extraction of Polyphenols during Fermentation in Microvinifications.

Grape cell wall polysaccharides influence the extraction of phenolic compounds during winemaking and consequently polyphenol concentrations in the final wine. During ripening, both compound groups undergo pronounced structural and compositional changes, resulting in a dynamic change of extractability. Grape cell wall polysaccharides from different ripe grapes were added to fermentations of Cabernet Sauvignon and Pinot noir grapes. Polyphenol-polysaccharide interactions affected the concentrations of tannins and monomeric flavanols in the wines depending on the maturity of the added polysaccharides. With higher polysaccharide maturity, the effects became more pronounced. Polysaccharides protected monomeric flavanols and tannin in Pinot noir, thereby increasing the concentrations, but they precipitated or masked these compounds in Cabernet Sauvignon. The added polysaccharides affected the concentrations in anthocyanins and polymeric pigments much less compared to the ripening status of the grapes. It was concluded that structural changes of polysaccharides during ripening affect the extraction of tannins and monomeric flavanols the most.

Chemometric Classification of Colombian Cacao Crops: Effects of Different Genotypes and Origins in Different Years of Harvest on Levels of Flavonoid and Methylxanthine Metabolites in Raw Cacao Beans.

The aim of this study was to evaluate the levels of chemical markers in raw cacao beans in two clones (introduced and regional) in Colombia over several years. Multivariate statistical methods were used to analyze the flavanol monomers (epicatechin and catechin), flavanol oligomers (procyanidins) and methylxanthine alkaloids (caffeine and theobromine) of cocoa samples. The results identified genotype as the main factor contributing to cacao chemistry, although significant differences were not observed between universal and regional clones in PCA. The univariate analysis allowed us to establish that EET-96 had the highest contents of both flavanol monomers (13.12 ± 2.30 mg/g) and procyanidins (7.56 ± 4.59 mg/g). In addition, the geographic origin, the harvest conditions of each region and the year of harvest may contribute to major discrepancies between results. Turbo cocoa samples are notable for their higher flavanol monomer content, Chigorodó cocoa samples for the presence of both types of polyphenol (monomer and procyanidin contents) and the Northeast cocoa samples for the higher methylxanthine content. We hope that knowledge of the heterogeneity of the metabolites of interest in each clone will contribute to the generation of added value in the cocoa production chain and its sustainability.

Higher Habitual Flavonoid Intakes Are Associated with a Lower Incidence of Diabetes.

ABSTRACTBackgroundHigher flavonoid intakes are hypothesized to confer protection against type 2 diabetes mellitus.ObjectivesWe aimed to 1) investigate associations between flavonoid intakes and diabetes, 2) examine the mediating impact of body fat, and 3) identify subpopulations that may receive the greatest benefit from higher flavonoid intakes in participants of the Danish Diet, Cancer, and Health Study followed up for 23 y.MethodsCross-sectional associations between baseline flavonoid intake, estimated using FFQs and the Phenol Explorer database, and body fat, estimated by bioelectrical impedance, were assessed using multivariable-adjusted linear regression models. Nonlinear associations between flavonoid intake and incident diabetes were examined using restricted cubic splines with multivariable-adjusted Cox proportional hazards models.ResultsAmong 54,787 participants (median age: 56 y; IQR: 52–60 y; 47.3% men), 6700 individuals were diagnosed with diabetes. Participants in the highest total flavonoid intake quintile (median, 1202 mg/d) had a 1.52 kg lower body fat (95% CI: –1.74, –1.30 kg) and a 19% lower risk of diabetes (HR: 0.81; 95% CI: 0.75, 0.87) after multivariable adjustments and compared with participants in the lowest intake quintile (median: 174 mg/d). Body fat mediated 57% (95% CI: 42, 83%) of the association between flavonoid intake and incident diabetes. Of the flavonoid subclasses, moderate to high intakes of flavonols, flavanol monomers, flavanol oligo + polymers, and anthocyanins were significantly associated with a lower risk of diabetes. Although associations were not modified by sex, smoking status, BMI, or physical activity (Pinteraction > 0.05 for all), findings on an absolute scale suggest that those at a higher risk (those with obesity) may benefit the most from a higher flavonoid intake.ConclusionsThe findings reported in this study suggest that a diet abundant in flavonoid-rich foods may help ameliorate diabetes risk, in part through a reduction in body fat.

Biosynthetic Pathway of Proanthocyanidins in Major Cash Crops.

Proanthocyanidins (PAs) are a group of oligomers or polymers composed of monomeric flavanols. They offer many benefits for human fitness, such as antioxidant, anticancer, and anti-inflammatory activities. To date, three types of PA have been observed in nature: procyanidins, propelargonidins, and prodelphinidins. These are synthesized as some of the end-products of the flavonoid pathway by different consecutive enzymatic activities, from the same precursor—naringenin. Although the general biosynthetic pathways of PAs have been reported in a few model plant species, little is known about the species-specific pathways in major crops containing different types of PA. In the present study, we identified the species-specific pathways in 10 major crops, based on the presence/absence of flavanol-based intermediates in the metabolic pathway, and found 202 orthologous genes in the reference genomic database of each species, which may encode for key enzymes involved in the biosynthetic pathways of PAs. Parallel enzymatic reactions in the pathway are responsible for the ratio between PAs and anthocyanins, as well as among the three types of PAs. Our study suggests a promising strategy for molecular breeding, to regulate the content of PAs and anthocyanins and improve the nutritional quality of food sources globally.

Aqueous Extract of Cocoa Phenolic Compounds Protects Differentiated Neuroblastoma SH-SY5Y Cells from Oxidative Stress

Cocoa is a rich source of polyphenols, especially flavanols and procyanidin oligomers, with antioxidant properties, providing protection against oxidation and nitration. Cocoa phenolic compounds are usually extracted with methanol/ethanol solvents in order to obtain most of their bioactive compounds; however, aqueous extraction seems more representative of the physiological conditions. In this study, an aqueous extract of cocoa powder has been prepared and chemically characterized, and its potential protective effect against chemically-induced oxidative stress has been tested in differentiated human neuroblastoma SH-SY5Y cells. Neuronal-like cultured cells were pretreated with realistic concentrations of cocoa extract and its major monomeric flavanol component, epicatechin, and then submitted to oxidative stress induced by a potent pro-oxidant. After one hour, production of reactive oxygen species was evaluated by two different methods, flow cytometry and in situ fluorescence by a microplate reader. Simultaneously, reduced glutathione and antioxidant defense enzymes glutathione peroxidase and glutathione reductase were determined and the results used for a comparative analysis of both ROS (reactive oxygen species) methods and to test the chemo-protective effect of the bioactive products on neuronal-like cells. The results of this approach, never tested before, validate both analysis of ROS and indicate that concentrations of an aqueous extract of cocoa phenolics and epicatechin within a physiological range confer a significant protection against oxidative insult to neuronal-like cells in culture.

Effect of Barrel-to-Barrel Variation on Color and Phenolic Composition of a Red Wine.

Tangible variation of sensory characteristics is often observed in wine aged in similar barrels. Barrel-to-barrel variation in barrel-aged wines was investigated in respect of the most important phenolic compounds of oenological interest. A red wine was aged in 49 medium-toasted oak (Quercus petraea) barrels, from four cooperages, for 12 months. The resulting wines were evaluated for chromatic characteristics, anthocyanin-related parameters, total phenols, flavonoids and non-flavonoids phenols, flavanol monomers, and oligomeric and polymeric proanthocyanidins. PCA and ANOVA were applied to investigate the relationships between barrels and to assess cooperage and individual barrel effect. Three cooperages influenced the wine similarly during aging. Anthocyanin-related parameters showed the highest variation, 25–37%, other phenolics varied 3–8.5%, and with two exceptions, chromatic characteristics changed 1.7–3%. The relationship between the number of barrels and the expected variation for each analytical parameter was calculated, as reference for future measurements involving barrel lots, either in wine production or experimental design.

Abstract MP66: Higher Habitual Flavonoid Intakes Are Associated With A Lower Incidence Of Diabetes

Introduction: The promotion of evidence-based diets is an important s trategy to mitigate the global health and economic burden of diabetes. Higher flavonoid intakes are associated with a lower risk of obesity and diabetes. Less clear are associations of the flavonoid subclasses with diabetes, the mediating impact of body fat, and the identification of subpopulations that may receive the greatest benefit. Hypothesis: Higher flavonoid intakes will be associated with lower body fat at baseline and a lower risk of diabetes during follow-up. Methods: Incident diabetes was assessed in 54,787 participants of the Danish Diet, Cancer, and Health Study followed-up for 23 years. Dietary intake and objective measures of body fat were assessed at baseline; habitual flavonoid intake was calculated using the Phenol-Explorer database and body fat was objectively assessed using bioelectrical impedance. Incidence of diabetes was obtained using Danish National Patient and Prescription Registries. Cross-sectional associations between flavonoid intakes and body fat were assessed using multivariable-adjusted linear regression models. Non-linear associations between flavonoid intake and incident diabetes were examined using restricted cubic splines based on multivariable-adjusted Cox proportional hazards models. Results: Among 54,787 participants without diabetes at baseline (median [IQR] age of 56 [52 - 60] years; (47.3%) men), 6,700 individuals were diagnosed with diabetes. Participants in the highest total flavonoid intake quintile (median, 1,202 mg/d) had a 1.52 kg lower body fat (95% CI: -1.74, -1.30) and a 19% lower risk of diabetes [HR (95% CI): 0.81 (0.75, 0.87)] after multivariable adjustments and compared to participants in the lowest intake quintile (median, 174 mg/d). Body fat mediated 51.6% of the association between flavonoid intake and incident diabetes. Neither smoking status, BMI, nor sex appeared to modify the association between total flavonoid intake and incident diabetes. However, the difference (flavonoid intake quintile 5 - quintile 1) in the 20-year estimated absolute risk of diabetes was greatest for current smokers (males: 2.19%, females: 1.65%) and those with a BMI ≥30 kg/m 2 (males: 5.56%, females: 4.59%), likely owing to the higher prevalence of diabetes in these “at risk” subgroups. Moderate to high intakes of flavonols, flavanol monomers, flavanol oligo+polymers, and anthocyanins, and the individual compounds within these subclasses, were associated with a lower risk of diabetes. Conclusion: In this Danish prospective cohort study, we observed that higher flavonoid intakes were cross-sectionally associated with lower body fat, and longitudinally associated with a lower risk of diabetes. Our results suggest that promoting a diet abundant in flavonoid-rich foods may help to ameliorate diabetes risk, in part through a reduction in body fat.

Effects of (-)-epicatechin on mitochondria.

Mitochondrial dysfunction is observed in a broad range of human diseases, including rare genetic disorders and complex acquired pathologies. For this reason, there is increasing interest in identifying safe and effective strategies to mitigate mitochondrial impairments. Natural compounds are widely used for multiple indications, and their broad healing properties suggest that several may improve mitochondrial function. This review focuses on (-)-epicatechin, a monomeric flavanol, and its effects on mitochondria. The review summarizes the available data on the effects of acute and chronic (-)-epicatechin supplementation on mitochondrial function, outlines the potential mechanisms involved in mitochondrial biogenesis induced by (-)-epicatechin supplementation and discusses some future therapeutic applications.

Emulsion gels as delivery systems for phenolic compounds: Nutritional, technological and structural properties

Polyphenols have interesting antioxidant properties and could help prevent certain diseases. Emulsion gels (EGs) have characteristics that make them a promising alternative system for supplying several bioactive compounds simultaneously, among them polyphenols. We produced four EGs containing olive oil, soy protein and a cold gelling agent based on alginate. One basic formulation (ES) contained only these ingredients and was used as a reference, while the other three also contained different solid polyphenol extracts from grape seed (G), grape seed and olive (O) or grape total (T), called ESG, ESO and EST, respectively. The corresponding EGs were prepared by mixing soy protein, alginate, water and one of these types of polyphenol extract (G, O or T), using a homogenizer. Then, the olive oil was gradually added to the mixture and finally, each mixture was placed in a metal container under pressure and chilled for 24 h until they formed an EG. The composition (including concentrations of phenolic metabolites), and technological and structural properties of these EGs were evaluated. Hydroxytyrosol was identified in all the EGs, but ESO showed the highest (P < 0.05) content. The EGs with added polyphenols showed contents of gallic acid, flavanol monomers and derivatives, with ESG showing the highest (P < 0.05) content. All the EGs showed optimal thermal stability, while colour and texture parameters were significantly influenced by the type of polyphenol extract added. No significant differences in the frequency or half-bandwidth of the 2923 and 2853 cm−1 infrared bands were observed.

Assessment of the formation of A-type proanthocyanidin by model reaction to blueberry extract and epicatechin

Blueberries are lacking in A-type proanthocyanidins, which assist in the prevention of urinary tract infections. Additive reactions to anthocyanins and a flavanol monomer promoted the formation of A-type proanthocyanidins. The four major anthocyanins of blueberry extracts are malvidin 3-O-glucoside, cyanidin 3-O-glucoside, delphinidin 3-O-glucoside and petunidin 3-O-glucoside. The model reaction of their two deglycosylation products, cyanidin and delphinidin with epicatechin, was investigated with different pH levels and under different thermal treatment conditions. At a pH 2.0–4.0, a nucleophilic addition occurred between the epicatechins and the anthocyanidins under flavylium form. Among the products, two colorless dimer adducts, A-type cyanidin-epicatechin (PAC-A2) and A-type delphinidin-epicatechin were obtained under optimal conditions (pH 2.0, at 90 °C, for 80 min, anerobic) and proved to be linked through a bicyclic bond (C4–C8, C2–O–C7) as detected in the A-type proanthocyanidins. This indicates that blueberry extract, originally rich in B-type proanthocyanidins, can produce A-type proanthocyanidins after processing.

Effect on Merlot red wine of fining agents mixture: application of the simplex centroid design

Abstract In the elaboration of young red wine, it is necessary to obtain a clear product with stable color. The clarity and stability can be obtained using fining agents. The objective of this study was to evaluate the combined effect of fining with pea protein isolate (PPI), bentonite, and polyvinylpyrrolidone (PVPP) on a red wine, using the experimental design of mixtures. Merlot wine was used to evaluate the changes on monomeric flavan-3-ol, turbidity and anthocyanin levels promoted by the fining compounds. For all the parameters, the adjusted models showed influence of the combination of the three fining agents. Together, bentonite and PVPP have synergistic effect on the reduction in monomeric flavanol levels. Such synergistic effect was also observed with PPI and PVPP combination for the reduction in turbidity. However, for this same characteristic (turbidity), the combination of PPI and bentonite has antagonistic effect. To achieve broader wine fining objectives, the simultaneous optimization of the three response variables demonstrated the importance of the presence of the three refining agents in the following proportions: 25% PPI, 43% PVPP and 32% Bentonite. The isolated use of these additives would not result in the same effect on the three studied variables.

Encapsulation of grape seed phenolics from winemaking byproducts in hydrogel microbeads – Impact of food matrix and processing on the inhibitory activity towards α-glucosidase

Hydrogel-based encapsulation systems were developed for grape seed phenolics recovered from winemaking byproducts. Proanthocyanidins, monomeric flavanols, flavonols and anthocyanins were extracted from grape seeds with 60% ethanol. Encapsulation of solubilized grape seed phenolics in microbeads with alginate-Ca++ or alginate-chitosan-Ca++ achieved efficiency of 78 and 92%, respectively, higher than those of pure catechin and proanthocyanidins.Encapsulated phenolics showed inhibitory activity towards the brush border enzyme α-glucosidase, which was chosen as a model bioactivity assay. Grape seed phenolics were retained in the hydrogel structure after mixing of the microbeads with bovine milk or rice drink, pasteurization of these beverages to achieve 7 decimal reductions of Mycobacterium avium subsp. paratubercolosis (equivalent to 72 °C for 91 s) as well as after intense heat treatment of the rice beverage to achieve 7 decimal reductions of Bacillus cereus (95 °C for 20 min).

Kinetic investigations of sulfite addition to flavanols

Flavanols are an important class of natural products occurring in almost all plants, fruits and vegetables; they have a great influence on wine ageing potential, astringency, colour stability and biological activities. In wine, flavanols react with sulfur dioxide (hbox {SO}_2), the most widely used preservative in oenology, leading to sulfonated products. Here we report a kinetic investigation, through LC-MS quantitative measurements carried out at different pH (3 and 4) and temperature values (23, 30, 40, 50 and 60, ^circ hbox {C}), of the reaction products obtained by hbox {SO}_2 addition to both monomeric (epicatechin and catechin) and dimeric flavanols (procyanidin B2 and procyanidin B3). The results proved that: (a) the major sulfonation route that leads quickly and in good yields to monomeric 4beta-sulfonated derivatives passes through the acid-catalysed depolymerisation of proanthocyanidins; (b) monomeric flavanols lead to the same 4beta-sulfonated products, although in a considerably slower manner, and also to other sulfonated regioisomers; (c) the kinetic data in our hands, in particular the temperature dependence of the observed rates, suggest the involvement of two completely different reaction mechanisms for the hbox {SO}_2 addition to dimeric and monomeric flavanol substrates; (d) direct sulfonation of epicatechin is slightly faster than that of catechin.