Dataset Information

Improving the Phloroglucinolysis Protocol and Characterization of Sagrantino Wines Proanthocyanidins.

ABSTRACT: Proanthocyanidins are key metabolites that explain wine sensorial character (bitterness and astringency) and red wine color changes during aging. Therefore, a fast and accurate method to evaluate the degree of polymerization and the structural composition of the polymeric proanthocyanidins is a crucial analytical tool. Phloroglucinolysis is the most used method for this analysis but, unfortunately, the phloroglucinol adducts of the monomeric flavan-3-ols are not commercially available, making the results less accurate. The aim of this work was the isolation by semi-preparative high performance liquid chromatography (HPLC) of these non-commercial compounds and their use for the development of an accurate UHPLC-MS/MS protocol. The purity of each adduct was established via quantitative ¹H-nuclear magnetic resonance (NMR) measurements with 3-trimethylsilyl-propionic-d4 acid sodium salt as the calibration standard. The developed method was applied to evaluate the proanthocyanidins profile of Sagrantino di Montefalco wines in comparison to other well-known tannic wines. Commercial, 6-8 years old Sagrantino wines were demonstrated to be very rich in epicatechin type B procyanidins, to have low galloylation %, and to have a high mean degree of polymerization of the proanthocyanidins with respect to the other analyzed wines.

SUBMITTER: Arapitsas P

PROVIDER: S-EPMC7922431 | biostudies-literature | 2021 Feb

REPOSITORIES: biostudies-literature

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Improving the Phloroglucinolysis Protocol and Characterization of Sagrantino Wines Proanthocyanidins.

Arapitsas Panagiotis P Perenzoni Daniele D Guella Graziano G Mattivi Fulvio F

Molecules (Basel, Switzerland) 20210219 4

Proanthocyanidins are key metabolites that explain wine sensorial character (bitterness and astringency) and red wine color changes during aging. Therefore, a fast and accurate method to evaluate the degree of polymerization and the structural composition of the polymeric proanthocyanidins is a crucial analytical tool. Phloroglucinolysis is the most used method for this analysis but, unfortunately, the phloroglucinol adducts of the monomeric flavan-3-ols are not commercially available, making th ...[more]

PMID: 33669538

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Project description:Introduction:In the last years, the utilization of phytomedicines has increased given their good therapeutic activity and fewer side effects compared to allopathic medicines. However, concerns associated with the biocompatibility and toxicity of natural compounds, limit the phytochemical therapeutic action, opening the opportunity to develop new systems that will be able to effectively deliver these substances. This study has developed a nanocomposite of chitosan (CS) functionalized with graphene oxide (GO) for the delivery of proanthocyanidins (PAs), obtained from a grape seed extract (Ext.). Methods:The GO-CS nanocomposite was covalently bonded and was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), atomic force microscopy (AFM) and by dynamic light scattering (DLS). The loading and release of Ext. from the GO-CS nanocomposite were performed in simulated physiological, and the cytotoxicity of the raw materials (GO and Ext.) and nanocomposites (GO-CS and GO-CS-Ext.) was determined using a human kidney cell line (HEK 293). Results:The chemical characterization indicated that the covalent union was successfully achieved between the GO and CS, with 44 wt. % CS in the nanocomposite. The GO-CS nanocomposite was thermostable and presented an average diameter of 480 nm (by DLS). The Ext. loading capacity was approximately 20 wt. %, and under simulated physiological conditions, 28.4 wt.% Ext. (g) was released per g of the nanocomposite. GO-CS-Ext. was noncytotoxic, presenting a 97% survival rate compared with 11% for the raw extract and 48% for the GO-CS nanocomposite at a concentration of 500 µg mL-1 after 24 hrs. Conclusion:Due to ?-? stacking and hydrophilic interactions, GO-CS was reasonably efficient in binding Ext., with high loading capacity and Ext. release from the nanocomposite. The GO-CS nanocomposite also increased the biocompatibility of PAs-rich Ext., representing a new platform for the sustained release of phytodrugs.

Project description:The presence and load of species of LAB at the end of the malolactic fermentation (MLF) were investigated in 16 wineries from the different Chilean valleys (Limarí, Casablanca, Maipo, Rapel, and Maule Valleys) during 2012 and 2013, using PCR-RFLP and qPCR. Oenococcus oeni was observed in 80% of the samples collected. Dominance of O. oeni was reflected in the bacterial load (O. oeni/total bacteria) measured by qPCR, corresponding to >85% in most of the samples. A total of 178 LAB isolates were identified after sequencing molecular markers, 95 of them corresponded to O. oeni. Further genetic analyses were performed using MLST (7 genes) including 10 commercial strains; the results indicated that commercial strains were grouped together, while autochthonous strains distributed among different genetic clusters. To pre-select some autochthonous O. oeni, these isolates were also characterized based on technological tests such as ethanol tolerance (12 and 15%), SO2 resistance (0 and 80 mg l-1), and pH (3.1 and 3.6) and malic acid transformation (1.5 and 4 g l-1). For comparison purposes, commercial strain VP41 was also tested. Based on their technological performance, only 3 isolates were selected for further examination (genome analysis) and they were able to reduce malic acid concentration, to grow at low pH 3.1, 15% ethanol and 80 mg l-1 SO2. The genome analyses of three selected isolates were examined and compared to PSU-1 and VP41 strains to study their potential contribution to the organoleptic properties of the final product. The presence and homology of genes potentially related to aromatic profile were compared among those strains. The results indicated high conservation of malolactic enzyme (>99%) and the absence of some genes related to odor such as phenolic acid decarboxylase, in autochthonous strains. Genomic analysis also revealed that these strains shared 470 genes with VP41 and PSU-1 and that autochthonous strains harbor an interesting number of unique genes (>21). Altogether these results reveal the presence of local strains distinguishable from commercial strains at the genetic/genomic level and also having genomic traits that enforce their potential use as starter cultures.

Dataset Information

Improving the Phloroglucinolysis Protocol and Characterization of Sagrantino Wines Proanthocyanidins.

Publications

Improving the Phloroglucinolysis Protocol and Characterization of Sagrantino Wines Proanthocyanidins.

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