Cocoa and Grape Seed Byproducts as a Source of Antioxidant and Anti-Inflammatory Proanthocyanidins

Phenolic compounds, which are secondary plant metabolites, are considered an integral part of the human diet. Physiological properties of dietary polyphenols have come to the attention in recent years. Especially, proanthocyanidins (ranging from dimers to decamers) have demonstrated potential interactions with biological systems, such as antiviral, antibacterial, molluscicidal, enzyme-inhibiting, antioxidant, and radical-scavenging properties. Agroindustry produces a considerable amount of phenolic-rich sources, and the ability of polyphenolic structures to interacts with other molecules in living organisms confers their beneficial properties. Cocoa wastes and grape seeds and skin byproducts are a source of several phenolic compounds, particularly mono-, oligo-, and polymeric proanthocyanidins. The aim of this work is to compare the phenolic composition of Theobroma cacao and Vitis vinifera grape seed extracts by high pressure liquid chromatography coupled to a quadrupole time-of-flight mass spectrometer and equipped with an electrospray ionization interface (HPLC-ESI-QTOF-MS) and its phenolic quantitation in order to evaluate the proanthocyanidin profile. The antioxidant capacity was measured by different methods, including electron transfer and hydrogen atom transfer-based mechanisms, and total phenolic and flavan-3-ol contents were carried out by Folin–Ciocalteu and Vanillin assays. In addition, to assess the anti-inflammatory capacity, the expression of MCP-1 in human umbilical vein endothelial cells was measured.This work was supported by the project AGL2011-29857-C03-02 and BFU2014-52433-C3-2-R (Spanish Ministry of Science and Innovation), as well as P10-FQM-6563 and P11-CTS-7625 (Andalusian Regional Government Council of Innovation and Science). The author Isabel Borrás Linares acknowledges financial support from the Spanish Ministry of Economy and Competitiveness (MINECO) and the European Social Fund (FSE) for the contract PTQ-13-06429. Authors are also grateful to the Universitat Rovira I Virgili for the Martí I Franquès Grant 2016PMF-POST-02 awarded to Salvador Fernández-Arroyo

Chemistry of Secondary Polyphenols Produced during Processing of Tea and Selected Foods

This review will discuss recent progress in the chemistry of secondary polyphenols produced during food processing. The production mechanism of the secondary polyphenols in black tea, whisky, cinnamon, and persimmon fruits will be introduced. In the process of black tea production, tea leaf catechins are enzymatically oxidized to yield a complex mixture of oxidation products, including theaflavins and thearubigins. Despite the importance of the beverage, most of the chemical constituents have not yet been confirmed due to the complexity of the mixture. However, the reaction mechanisms at the initial stages of catechin oxidation are explained by simple quinone–phenol coupling reactions. In vitro model experiments indicated the presence of interesting regio- and stereoselective reactions. Recent results on the reaction mechanisms will be introduced. During the aging of whisky in oak wood barrels, ellagitannins originating from oak wood are oxidized and react with ethanol to give characteristic secondary ellagitannins. The major part of the cinnamon procyanidins is polymerized by copolymerization with cinnamaldehyde. In addition, anthocyanidin structural units are generated in the polymer molecules by oxidation which accounts for the reddish coloration of the cinnamon extract. This reaction is related to the insolubilization of proanthocyanidins in persimmon fruits by condensation with acetaldehyde. In addition to oxidation, the reaction of polyphenols with aldehydes may be important in food processing

Use of new methodologies to study phenolic compounds implicated in beer staling

The goal of our thesis was to better understand the fate of polyphenols through beer storage. First, new methodologies were needed to assess what happens to polyphenols in the bottled beer. They were optimized on fresh beer samples. NP-HPLC-ESI(-)-MS/MS with addition of ammonium salt revealed efficient to quantify monomers to trimers in a Sephadex LH20 acetone/water (70/30, v/v) beer extract: up to 3 ppm P1-P3 were measured in PVPP-treated beers vs. 10 ppm in silica gel-filtered beers. Thiolysis of such extracts indicated that most beer dimers are procyanidins whilst most trimers are prodelphinidins. Detailed structures of each oligomer were determined by reversed phase. As expected according to thioacidolysis data, most beer proanthocyanidins carry a catechin as terminal unit. The analysis of higher oligomers extracted by dialysis and thiolyzed lead us to conclude that natural beer oligomers exhibit a relatively low DP whilst transformed oligomers probably account for most of the heavy flavanoid content. The optimized methods were then applied on aged beers. Three lager beers differently stabilized before bottling in glass or PET bottles were monitored over a one-year period of storage at 20°C. In parallel, beer color was measured. Structural rearrangements of polyphenols revealed to be the main source of color changes. The evolution of color was the same in the silica gel-filtered beer as in identically bottled PVPP-treated samples, despite the high flavanoid dimers content of the former. This suggests that only monomers must be considered. Model media were also investigated by the same method. (+)-Catechin emerged as the precursor of less polar products characterized by a yellow-brown color. Similar structures were found in aged beers spiked with (+)-catechin. None of the usual global assays revealed efficient to predict the extent of beer polyphenol degradation.Doctorat en sciences agronomiques et ingénierie biologique (AGRO 3)--UCL, 200

Structure, Organoleptic Properties, Quantification Methods, and Stability of Phenolic Compounds in Beer-A Review

Beer composition changes through storage, altering the quality of the product. In the past decade, many papers have been devoted to the compounds responsible for aged-beer off-flavors, mainly trans-2-nonenal, methional, and dimethyltrisulfide. Due to their huge antioxidant activity, polyphenols have often been described as key compounds for limiting beer staling. Yet phenolic structures also evolve through storage. Low-molecular-weight phenols like 4-vinylsyringol can impart off-flavors in aged beer, whilst flavonoids strongly influence astringency, haze, and color. The instability of stilbenes, prenylchalcones, and derived flavanones could also modify their health potential through storage. After reviewing the structures and properties of all phenolic compounds found in beer, this paper will try to assess the impact of their degradation through aging. Extraction procedures for their quantification and treatments for their removal are also described

Involvement of flavanoids in beer color instability during storage.

Besides Maillard reactions, structural rearrangements of flavan-3-ol monomers cause color changes in beer during storage. Acetone/water-soluble fractions (70/30, v/v) of three lager beers of the same batch, differently stabilized before bottling in glass or poly(ethylene terephthalate) (PET) bottles, were monitored by normal-phase HPLC-ESI(-)-MS/MS over a 1-year period of storage at 20 degrees C. In parallel, beer color was monitored by the European Brewery Convention assay. The evolution of color was similar in the silica gel-filtered beer to that in identically bottled and stored poly(vinylpolypyrrolidone)-treated samples, despite the high flavanoid dimers content of the former. On the other hand, color evolved more rapidly in the PET bottle, suggesting a key role of oxygen. The kinetics was still increased in model media containing (+)-catechin, while no color was detected when normal-phase HPLC-fractionated dimers or trimers were investigated. (+)-Catechin emerged as the precursor of less polar products, characterized by a yellow-brown color. MS/MS enabled us to identify these products as issued from the oxidation and intramolecular additions of dehydrodicatechin B4. Similar structures were found in aged beers spiked with (+)-catechin. Beer storage in the absence of oxygen and at low temperature is recommended so as to minimize the synthesis of such pigments

Use of RP-HPLC-ESI(-)-MS/MS to differentiate various proanthocyanidin isomers in lager beer extracts

Normal-phase high-performance liquid chromatography electrospray ionization(-) tandem mass spectrometry (NP-HPLC-ESI(-)-MS/MS) and thioacidolysis analyses recently have revealed the presence of (+)-catechin, (-)-epicatechin, procyanidin dimers, and prodelphinidin trimers in acetone/water (70/30, vol/vol) LH-20 extracts of lager beers. In this study, detailed structures were determined by reversed-phase (RP) HPLC-ESI(-)MS/MS. Four dimers were identified: three procyanidins (B1, B3, and 134) and one prodelphinidin (133). Previously detected in hop or malt, three trimers; (the procyanidin C-4 alpha-8-C-4 alpha-8-C and two prodelphinidins, GC-4 alpha-8-C-4 alpha-8-C and GC-4 alpha-8-GC-4 alpha-8-C) were distinguished for the first time in beer. As expected based on previous thioacidolysis data, most beer proanthocyanidins carried a catechin as the terminal unit