Self-aggregation of oxidized procyanidins contributes to the formation of heat-reversible haze in apple-based liqueur wine

Micro‑oxygenation in red wines: Current status and future perspective

Micro‑oxygenation (MOX) is the technology providing a slow and continuous oxidation reaction in the whole winemaking process to improve wine quality. However, traditional methods of oxygen management struggle to achieve a precise control over oxygen at critical process points, failing to meet the personalized and diverse production demands of wine. In this paper, an overview of three application stages of MOX, and the detailed dosage and duration at each stage were summarized. In addition, the application prospect of the new MOX application facility in wine production was proposed. Compared to passive MOX, active MOX could allow a more precise control of oxygen. The innovation of MOX equipment based on active MOX technique will be an inspiring interest in the research of winemaking. The integration and development of precise MOX will achieve the targeted control of wine quality and the creation of distinctive characteristics of wine style.

Interactions between Salivary Proteins and Apple Polyphenols and the Fate of Complexes during Gastric Digestion

Beneficial polyphenols in apples can reach the stomach as complexes formed with salivary proteins. The present study aimed at documenting the interactions between salivary proteins and cider apple polyphenols and the fate of complexes during gastric digestion. A polyphenolic extract was mixed with human saliva, and interactions were characterized by analyzing proteins and polyphenols in the insoluble and soluble fractions of the mixtures, before and after in vitro gastric digestion. Results confirmed that proline-rich proteins can efficiently precipitate polyphenols and suggested that two zinc-binding proteins can also form insoluble complexes with polyphenols. The classes of polyphenols involved in such complexes depended on the polyphenol-to-protein ratio. In vitro gastric digestion led to extensive proteolysis of salivary proteins, and we formulate the hypothesis that the resulting peptides can interact with and precipitate some procyanidins. Saliva may therefore partly modulate the bioaccessibility of at least procyanidins in the gastric compartment.

A Review on Wine Flavour Profiles Altered by Bottle Aging

The wine flavour profile directly determines the overall quality of wine and changes significantly during bottle aging. Understanding the mechanism of flavour evolution during wine bottle aging is important for controlling wine quality through cellar management. This literature review summarises the changes in volatile compounds and non-volatile compounds that occur during wine bottle aging, discusses chemical reaction mechanisms, and outlines the factors that may affect this evolution. This review aims to provide a deeper understanding of bottle aging management and to identify the current literature gaps for future research.

Role of Yeast Mannoproteins in the Interaction between Salivary Proteins and Flavan-3-ols in a Cell-Based Model of the Oral Epithelium

Astringency is a highly complex sensation which involves multiple mechanisms occurring simultaneously, such as the interaction between flavan-3-ols and salivary proteins (SP). Moreover, astringency development can be affected by the presence of polysaccharides such as mannoproteins (MP). The aim of this work was to evaluate the molecular mechanisms whereby MP could modulate the astringency elicited by tannins, using a cell-based model of the oral epithelium (TR146 cells), and the effect of salivary proteins on these interactions. The binding of flavan-3-ols to oral cells was evaluated by DMACA assay, while the content of unbound flavan-3-ols after the interactions was assessed by means of HPLC-DAD-MS. Results obtained confirm the existence of cell-tannin interactions, that can be partially inhibited by the presence of SP and/or MP. The most significant decrease was obtained in the system containing MPF (38.16%). Both mannoproteins assayed seem to have modulating effect on flavan-3-ol-SP interactions, acting by two different mechanisms: MPF would lead to the formation of SP/MPF/flavan-3-ols ternary soluble aggregates, while MPL seems to prevent flavan-3-ol-saliva interaction by a competitive mechanism, i.e., MPL would reduce cell-tannin interactions, similar to SP. This study suggests that mannoproteins with different compositional characteristics could exhibit preferential interaction with distinct flavan-3-ol families.

Co-pigmentation of strawberry anthocyanins with phenolic compounds from rooibos

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Strawberry anthocyanins may be co-pigmented with rooibos phenolics.

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Adding rooibos extract enhanced color and heat stability of strawberry anthocyanins.

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Green and fermented rooibos phenolics acted as potential co-pigments (CP).

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A flavonoid-rich fraction of green rooibos extract provided the most potent CPs.

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Flavonoids luteolin and orientin were effective CPs for pelargonidin 3-glucoside.

Anthocyanin-rich strawberry model solutions were co-pigmented with rooibos phenolics to enhance color and heat stability. The addition of green and fermented rooibos extracts at pigment-to-co-pigment molar ratios of 1:10, 1:50, and 1:100 pelargonidin-3-glucoside equivalents: orientin equivalents induced hyper- and bathochromic shifts at room temperature and during thermal processing at 80 °C for an hour. Co-pigmentation effects on hyperchromic shift were up to 96%, and bathochromic shift reached 19 nm when adding flavonoid-rich fractions of green rooibos phenolics. Following the co-pigmentation tests with rooibos extracts, selected pure phenolic co-pigments were tested for their monomeric contribution to the observed co-pigmentation effects. Orientin was identified as a potent co-pigment for pelargonidin-3-glucoside, showing stronger co-pigmentation effects than that of its aglycon luteolin. Additionally, orientin had the most pronounced bathochromic shift in heat-treated solutions. Rooibos extracts, particularly flavonoid-rich fractions composed of luteolin, apigenin, and quercetin glycosides, are suggested as color enhancers and stabilizers for strawberry products.

Study of the oxidative evolution of tannins during Syrah red wines ageing by tandem mass spectrometry

Red wine is a very complex medium in which condensed tannins undergo many modifications during winemaking and bottle ageing. These reactions have an impact on the organoleptic properties. This work aimed to highlight tannins evolution related to wine evolution by studying three vintages of Syrah wines. An accelerated oxidation was also undertaken in order to evaluate the ability of this oxidation to imitate natural evolution. After chemical depolymerization of the tannins, the monitoring of 6 types of markers at two oxidation levels was investigated. An evolution of the tannin oxidation state during ageing evidenced by the increase of the markers of the second oxidation level was observed. In the 2018 oxidized wine sample, the first oxidation level markers were similar to the 2014 vintage but the second oxidation level markers were higher than other vintages, indicating a more advanced state of tannin oxidation.

Preparative isolation of apple flavan-3-ols monomers and oligomers using pH-zone-refining centrifugal partition chromatography combined with reversed-phase liquid chromatography

Flavan-3-ols (catechin monomers and procyanidins) are the main class of polyphenols in apples and are found in high concentrations in cider apple varieties. They are known to be involved in bitterness and astringency in apple-based beverages, and also contribute to polyphenol nutritional intake.Therefore, highly purified flavan-3-ol fractions isolated from raw materials are needed to study their various properties. For this purpose, a gentle strategy combining pH-zone-refining centrifugal partition chromatography (pH-ZRCPC) and preparative reversed-phase liquid chromatography (Prep-RPLC) was developed to recover one hundred milligrams of a high purity apple flavan-3-ol fraction. First, pH-ZRCPC fractionation in descending mode was optimized to remove hydroxycinnamic acid derivatives using a biphasic mixture composed of ethyl acetate/n-butanol/water (3/2/5, v/v). Trifluoroacetic acid and sodium hydroxide were used as retainer and eluter, in the upper and lower phases, respectively. Secondly, Prep-RPLC separation was carried out in isocratic mode at 20% ACN to remove dihydrochalcones. Finally, from one gram of a crude polyphenol extract, four hundred and nine milligrams of a highly purified fraction of flavan-3-ols with an average degree of polymerization close to 3.1 was obtained with 73% recovery.

Methacrylate-functionalized proanthocyanidins as novel polymerizable collagen cross-linkers - Part 1: Efficacy in dentin collagen bio-stabilization and cross-linking

OBJECTIVE

The aim of the study was to investigate the effects of methacrylate-functionalized proanthocyanidins (MAPAs) on dentin collagen's bio-stabilization against enzymatic degradation and crosslinking capability.

METHODS

Three MAPAs were synthesized via varying methacrylate (MA) to proanthocyanidins (PA) feeding ratios of 1:2, 1:1, and 2:1 to obtain MAPA-1, MAPA-2, and MAPA-3, respectively. The three MAPAs were structurally characterized by proton nuclear magnetic resonance (¹H NMR) and Fourier transform infrared (FTIR) spectroscopic methods. 5-μm-thick dentin films were microtomed from dentin slabs of third molars. Following demineralization, films or slabs were treated with 1% MAPAs or PA in ethanol for 30 s. Collagen bio-stabilization against enzymatic degradation was analyzed by weight loss (WL) and hydroxyproline release (HYP) of films, as well as scanning electron microscopy (SEM) on dentin slabs. Crosslinking capacity and interactions of MAPAs with collagen were investigated by FTIR. Data were analyzed by ANOVA and Tukey's test (α = 0.05%).

RESULTS

MA:PA feeding ratios affected MAPAs' chemical structures which in turn led to different collagen stabilization efficacy against degradation and varied collagen crosslinking capabilities. Higher collagen stabilization efficacy was detected using MAPA-1 (WL 10.52%; HYP 13.53 μg/mg) and MAPA-2 (WL 5.99%; HYP 11.02 μg/mg), which was comparable to that using PA (WL 8.79%; HYP 13.17 μg/mg) (p > 0.05), while a lower collagen stability occurred in MAPA-3 (WL 38.48%; HYP 29.49 μg/mg), indicating excessive MA-functionalization would compromise its stabilization efficacy. In comparison, complete digestion was detected for untreated collagen (WL 100%; HYP 102.76 μg/mg). The above results were consistent with collagen crosslinking efficacy of the three MAPAs revealed by SEM and FTIR.

SIGNIFICANCE

A new class of novel polymerizable collagen cross-linkers MAPAs was synthesized and shown that, when appropriate MA:PA ratios were applied, the resulting MAPAs could render high collagen stability and the ability to copolymerize with resin monomers, overcoming the drawbacks of PA. These new polymerizable crosslinkers, when included in adhesives, could lead to long-lasting dentin bonding.

Effects of Blueberry and Black Carrot Extracts Addition on Antioxidant Properties and Protein-Precipitating Capacity of Ultrasound-Treated Cider

The results presented in this study highlight the level of total phenolic content (TPC), total flavonoid content (TFC) and protein-precipitating capacity (PPC) correlated with the antioxidant capacity of new cider varieties enriched with valuable bio compounds by the addition of blueberry and black carrot extracts. The cider variants were treated with ultrasound (constant frequency of 20 kHz) at 20%, 30% and 40% amplitude (A) for two, five or seven minutes. TPC determination was performed by Folin–Ciocâlteu method and TFC was determined by an aluminum chloride colorimetric method. The antioxidant capacity was determined by ferric-reducing antioxidant power assay (FRAP), ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) assay and DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity. The results showed that the antioxidant performance indicators (FRAP, ABTS and DPPH) were positively correlated with the TPC and TFC of the ultrasound-treated cider variants, suggesting that the content of these bio compounds may be improved by the treatments applied. The highest mean values for TPC and TFC were found in the cider variant enriched with black carrot extract (0.3%, v/v), subsequently ultrasound-treated (A20%, five minutes) Conclusively, the extracts used in this study could improve the antioxidant capacity of the cider, especially in case of variants ultrasound-treated.

Analysis of factors related to browning of Dangshan pear (Pyrus spp.) wine

The effects of different dissolved oxygen concentrations (DOC) on the browning degree, amino acids, total phenols, reducing sugars, polyphenoloxidase (PPO), peroxidase (POD), phenylalanine ammonia-lyase (PAL) of pear wine, and the relationship between various quality indicators and browning degree were investigated. Dynamic model fitting analysis of the changes of physiochemical indicators of pear wine in the storage process were performed. The importance of the physiochemical indicators effect on the browning of pear wine during the storage process was analyzed by OPLS (orthogonal partial least squares discriminant analysis), and the effect of dissolved oxygen on the browning of pear wine was systematically revealed. The results showed that dissolved oxygen, total phenols and amino acids had the greatest influence on the browning degree of pear wine. It provided a theoretical basis for revealing the browning mechanism and inhibiting the browning of pear wine.

Interactions of arabinan-rich pectic polysaccharides with polyphenols

Given the high prevalence of arabinan side chains in pectic polysaccharides, this work aims to unveil the impact of their structural diversity on pectic polysaccharides-polyphenol interactions. To assess the effect of arabinan branching degree, sugar beet arabinans (branched and debranched) were used and compared to the well-known structure of apple arabinan and other pectic polysaccharides. Furthermore, arabinans contribution to pectic polysaccharides/polyphenol interactions was assessed. The interactions were evaluated using chlorogenic acid, phloridzin and procyanidins (degree of polymerization of 9). Linear arabinans had 8-fold and 2-fold higher retention for chlorogenic acid and phloridzin, respectively, than branched arabinans. This trend was also observed for the interaction of arabinans with procyanidins. However, arabinans with covalently linked polyphenols showed lower interactions. The interactions involved between arabinans and polyphenols explained 1-28 % of the interactions of pectic polysaccharides, allowing us to conclude that the whole polysaccharide structure is more relevant for polyphenol interactions than each part.