Moringa oleifera leaf supplementation as a glycemic control strategy in subjects with prediabetes

This article belongs to the Section Phytochemicals and Human Health.Moringa oleifera (MO) is a multipurpose plant with a high polyphenol content, which is being increasingly consumed to lessen the risk of chronic metabolic diseases such as Type 2 diabetes; however, scientific evidence from clinical trials is scarce. A double-blind, randomized, placebo-controlled, parallel group intervention study with MO leaves as a food supplement was conducted in subjects with prediabetes. They consumed six daily capsules of MO dry leaf powder (2400 mg/day) (MO, n = 31) or placebo (PLC, n = 34) over 12 weeks. Glycemia, appetite-controlling hormones and gut microbiota composition were studied. ANCOVA with the fixed factor “treatment” and the basal value as covariate was used to compare the change score between the groups. The results showed significant differences between groups in the rate of change of fasting blood glucose (FBG) and glycated hemoglobin (HbA1c), which showed opposite directions during the intervention, decreasing in MO and increasing in PLC. No different change scores were found between the groups in microbiota, hepatic and renal function markers or the appetite-controlling hormones measured. In conclusion, MO supplementation resulted in favorable changes in glycaemia markers compared to placebo in the subjects with prediabetes studied, suggesting that MO might act as a natural antihyperglycemic agent.This article is part of the R + D + i Project AGL2017-86044-C2-1-R, funded by CIN/AEI/10.13039/501100011033/ and “ERDF A way of making Europe”.Peer reviewe

Quantitative analysis of Bordeaux red wine precipitates by solid-state NMR: Role of tartrates and polyphenols

Stability of wines is of great importance in oenology matters. Quantitative estimation of dark red precipitates formed in Merlot and Cabernet Sauvignon wine from Bordeaux region for vintages 2012 and 2013 was performed during the oak barrel ageing process. Precipitates were obtained by placing wine at -4 degrees C or 4 degrees C for 2-6 days and monitored by periodic sampling during a one-year period. Spectroscopic identification of the main families of components present in the precipitate powder was performed with C-13 solid-state CPMAS NMR and 1D and 2D solution NMR of partially water re-solubilized precipitates. The study revealed that the amount of precipitate obtained is dependent on vintage, temperature and grape variety. Major components identified include potassium bitartrate, polyphenols, polysaccharides, organic acids and free amino acids. No evidence was found for the presence of proteins. The influence of main compounds found in the precipitates is discussed in relation to wine stability. (c) 2016 Published by Elsevier Ltd

Transfer of Tannin Characteristics from Grape Skins or Seeds to Wine-Like Solutions and their Impact on Potential Astringency

A simulated maceration was carried out with skins or seeds of Aglianico, Merlot and Cabernet Sauvignon grape cultivars in order to study the entity of the transfer of tannins from grape to wine. The structural characteristics of skins and seeds extracts (native tannins) and corresponding wine-like solutions (macerated tannins) were analysed by phloroglucinolysis. Their potential astringency was evaluated according to the reactivity towards salivary proteins by the Saliva Precipitation Index (SPI). From grape to wine-like solution, the transfer of structural characteristics varied differently for skins and seeds. A significant influence of extraction method and grape variety was also stated, principally as regard the percentage of prodelphinidins (%P) for skins, and of galloylation (%G) for seeds. For some parameters that were able to differentiate grapes through the maceration process, a cultivar effect emerged. Reactivity of tannins also differed, but not for seeds. For Aglianico native and macerated tannins, the highest in SPIs, seeds monomers and oligomers were quantified by HPLC/MS. Principal Component Analysis (PCA) allowed to reveal the structural characteristics mainly associated with the reactivity of tannins towards salivary proteins. The proanthocyanidins content and the %G increased potential astringency, while it was reduced by the %P

Effect of polyvinylpolypyrrolidone treatment on rosés wines during fermentation: Impact on color, polyphenols and thiol aromas

Fining treatment with polyvinylpolypyrrolidone (PVPP) is often used during winemaking of rose wines. It can modulate the intensity and hue of their pink color and prevent some organoleptic degradations. In this paper, the effect of PVPP treatments on rose wine during fermentation was investigated by measuring color, polyphenol content and thiol aromas. As expected, colorimetry results showed a decrease in color, indicating some adsorption of anthocyanins and other pigments. This was confirmed by UPLC-ESI-MS/MS analyses. Specific adsorption of certain families of polyphenols was evidenced. Flavonols, flavanols and anthocyanins, especially coumaroylated anthocyanins were preferentially adsorbed by PVPP. The thiol content (3-sulfanylhexyl acetate (3SHA) and 3-sulfanylhexan-1-ol (3SH)) was usually higher after PVPP treatments, in a dose dependent manner. A possible explanation is that the partial adsorption of some polyphenols at an early stage of fermentation would later limit the amount of quinone compounds able to trap thiol aromas

Influence of phenolic compounds on the sensorial perception and volatility of red wine esters in model solution: an insight at the molecular level

International audienceImpact of (+)-catechin and gallic acid on sensory perception and volatility of isoamyl acetate, ethyl isobutyrate, ethyl butyrate and ethyl octanoate was investigated in model solutions, by means of triangle tests, detection threshold determination and HS-GC-MS analyses. Catechin significantly altered the sensory perception of most esters (ethyl isobutyrate, ethyl butyrate and ethyl octanoate) while gallic acid displayed no impact. Ethyl butyrate and ethyl octanoate odour thresholds doubled or tripled in the presence of catechin, underlining a retention impact of phenolic compounds in liquid matrix. The headspace analyses displayed a decrease only in ethyl octanoate volatility in presence of catechin, whereas no significant difference in other esters concentrations was observed. This study indicated that phenolic compounds have a variable impact on aroma compounds' volatility and their sensory perception. The polarity of phenolic and volatile compounds as well as their spatial conformation also appeared to influence the interaction strength

Rosé Wine Fining Using Polyvinylpolypyrrolidone: Colorimetry, Targeted Polyphenomics, and Molecular Dynamics Simulations

Polyvinylpolypyrrolidone (PVPP) is a fining agent polymer used in winemaking to adjust rose wine color and to prevent organoleptic degradations by reducing polyphenol content. The impact of this polymer on color parameters and polyphenols of rose wines was investigated, and the binding specificity of polyphenols toward PVPP was determined. Color measured by colorimetry decreased after treatment, thus confirming the adsorption of anthocyanins and other pigments. Phenolic composition was determined before and after fining by targeted polyphenomics (Ultra Performance Liquid Chromatography (UPLC)-Electrospray Ionization(ESI)-Mass Spectrometry (MS/MS)). MS analysis showed adsorption differences among polyphenol families. Flavonols (42%) and flavanols (64%) were the most affected. Anthocyanins were not strongly adsorbed on average (12%), but a specific adsorption of coumaroylated anthocyanins was observed (37%). Intermolecular interactions were also studied using molecular dynamics simulations. Relative adsorptions of flavanols were correlated with the calculated interaction energies. The specific affinity of coumaroylated anthocyanins toward PVPP was also well explained by the molecular modeling

J Microbiol Methods

The existing methods for testing proteolytic activity are time consuming, quite difficult to perform, and do not allow real-time monitoring. Proteases have attracted considerable interest in winemaking and some yeast species naturally present in grape must, such as Metschnikowia pulcherrima, are capable of expressing this activity. In this study, a new test is proposed for measuring proteolytic activity directly in fermenting grape must, using azocasein, a chromogenic substrate. Several yeast strains were tested and differences in proteolytic activity were observed. Moreover, analysis of grape must proteins in wines revealed that protease secreted by Metschnikowia strains may be active against wine proteins