Polyphenols from Grape Pomace: Functionalization of Chitosan-Coated Hydroxyapatite for Modulated Swelling and Release of Polyphenols

[Image: see text] Chitosan is known for its specific antibacterial mechanism and biodegradability, while polyphenols are known for their antioxidant and anti-inflammatory properties: coupling these properties on a surface for bone contact, such as hydroxyapatite, is of great interest. The system developed here allows the combination of hydroxyapatite, chitosan, and polyphenol properties in the same multifunctional biomaterial in order to modulate the host response after implantation. Crosslinked chitosan is used in this research to create a stable coating on hydroxyapatite, and then it is functionalized for a smart release of the polyphenols. The release is higher in inflammatory conditions and lower in physiological conditions. The properties of the coated and functionalized samples are characterized on the as-prepared samples and after the samples are immersed (for 24 h) in solutions, which simulate the inflammatory and physiological conditions. Characterization is performed in order to confirm the presence of polyphenols grafted within the chitosan coating, the stability of grafting as a function of pH, the morphology of the coating and distribution of polyphenols on the surface, and the redox reactivity and radical scavenging activity of the functionalized coating. All the results are in line with previous results, which show a successful coating with chitosan and functionalization with polyphenols. Moreover, the polyphenols have a different release kinetics that is faster in a simulated inflammatory environment compared to that in the physiological environment. Even after the release tests, a fraction of polyphenols are still bound on the surface, maintaining the antioxidant and radical scavenging activity for a longer time. An electrostatic bond occurs between the negative-charged polar groups of polyphenols (carboxyls and/or phenols) and the positive amide groups of the chitosan coating, and the substitution of the crosslinker by the polyphenols occurs during the functionalization process

Valorization of wine industry by-products: Characterization of phenolic profile and investigation of potential healthy properties

In the last years, the importance of food waste management and recovery is emphasized by the international guidelines to promote a circular economy approach. Wine industry is one of the sectors with the highest waste production, with a potential negative environmental impact. Winemaking by-products are mainly used to produce distillates, fertilizers and livestock feed, but alternative approaches for their management could be the formulation of healthy products. The aim of this study was the application of in vitro methods for a preliminary evaluation of the phenolic pattern and the associated biological properties of winemaking by-products from different red grape varieties. The methods were: 1) Folin-Cocalteau's assay for the assessment of total polyphenol content; 2) the vanillin assay for the quantification of total procyanidin content; 3) the pH differential method for the determination of total anthocyanin content; 4) DPPH and FRAP assays for the measurement of total antioxidant activity; 4) High Performance Thin Layer Chromatography for separation of phenolic substances and assessment of their antioxidant capacity; 5) dipeptidyl peptidase (DPPIV) inhibition assay to evaluate possible effects on glucose homeostasis. The results showed that grape pomace, particularly when including seeds, was a valuable source of polyphenols with significant antioxidant potential and promising activity on DPPIV, supporting its use in formulating healthy foods/food supplements

Polyphenolic Characterization of Grape Skins and Seeds of Four Italian Red Cultivars at Harvest and after Fermentative Maceration

Agro-industry byproducts can still contain large amounts of phenolic compounds, and one of the richest sources are grape skins and seeds as grape pomace, both fermented (red winemaking) and unfermented (white winemaking). The residual polyphenolic content depends on various factors such as grape variety, vintage, and winemaking technique. In this work, four red grape varieties cultivated in northern Italy were studied: Albarossa, Barbera, Nebbiolo, and Uvalino. The work was aimed at studying the polyphenolic composition of skins and seeds from fresh grapes and from the corresponding pomace after fermentative maceration, to assess the actual importance of the varietal differences when processing winemaking byproducts for the extraction of phenolic compounds. The skin and seed extracts were prepared by solvent extraction with a 50% hydroalcoholic solution. The polyphenolic composition of all extracts was determined by spectrophotometry and high-performance liquid chromatography (HPLC); the content and the monomer composition of condensed tannins were determined by phloroglucinolysis; the antioxidant capacity was measured with the ABTS (2,2’-azinobis-(3-ethylbenzothiazoline-6- sulfonate)) method. The antioxidant capacity was higher for the seeds than for the skins, and it was positively correlated with the condensed tannins content. Significant differences in polyphenolic composition of fresh grape skins and seeds were observed between the different cultivars. In particular, Barbera and Albarossa skins were significantly distinguished from Nebbiolo and Uvalino skins for a higher content of anthocyanins and a lower content of vanillin-reactive flavans and condensed tannins; regarding seeds, Barbera and Albarossa had a lower content of vanillin-reactive flavans, proanthocyanidins, and condensed tannins than Nebbiolo and Uvalino. The winemaking process extracted the phenolic compounds to a different extent from skins and seeds, regardless of the cultivar. The differences between cultivars in the polyphenolic profile disappeared after fermentative maceration

Deposition of thin films containing carboxylic acid groups on polyurethane foams by atmospheric pressure non-equilibrium plasma jet

Thin films containing carboxylic acid groups are deposited on open-cell polyurethane (PU) foams by using an atmospheric pressure non-equilibrium plasma jet, in dielectric barrier discharge configuration, fed with helium, acrylic acid and ethylene. The arrangement of the plasma jet, the sample holder, and the substrate is carefully optimized to enable the penetration of the plasma ejected from the remote source throughout the threedimensional (3D) porous structure of the foam, and, therefore, to achieve the uniform coverage of the entire substrate. X-ray photoelectron spectroscopy analyses and scanning electron microscopy observations confirm that both the outer and the inner surfaces of the foam can be functionalized with the plasma-deposited coating, showing moderate changes in surface chemical composition and coating thickness moving from the exterior to the interior of the plasma-treated samples. The ability of the foams to adsorb heavy metals from water is tested through evaluation of cadmium ions (Cd2+) removal. The foams adsorption capacity can increase more than 10 times after plasma deposition and remains unchanged over 8 adsorption-release cycles

Polyphenolic Composition and In Vitro Antioxidant Activity of Red Grape Seeds as Byproducts of Short and Medium-Long Fermentative Macerations

The polyphenolic composition and antioxidant activity of grape seeds, as byproducts of red winemaking, depend on various factors, such as grape cultivar, vintage effect, grape maturity and winemaking methods. In the present work, the influence of the maceration length on the polyphenolic and antioxidant characteristics of the seeds of four Italian red grape cultivars (‘Barbera’, ‘Grignolino’, ‘Nebbiolo’, and ‘Uvalino’), sampled from the fermentation tanks after short (two days) and medium-long (7–21 days) macerations, was studied with spectrophotometric methods, high-performance liquid chromatography (HPLC), and three different antioxidant assays (2,2′-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS), ferric reducing antioxidant power (FRAP) and 2,2 diphenyl-1-picrylhydrazyl (DPPH)). The total polyphenolic content (gallic acid equivalent (GAE)) of the seeds sampled after short macerations ranged between 24.5 and 60.1 mg/g dry weight (DW), and it dropped to 20.0–37.5 mg/g DW after medium-long macerations. The polyphenolic profile of the shortly macerated seeds was related to the varietal characteristics, while, after longer macerations, the influence of the maceration length prevailed on the cultivar effect. The multiple in vitro antioxidant activity tests (ABTS, FRAP and DPPH), although based on different mechanisms capable of highlighting behavioral differences between the different polyphenolic compounds, were highly correlated with each other and with the polyphenolic parameters; the qualitative differences between the matrices in the polyphenolic profile were probably less important than the quantitative differences in the polyphenolic content. The relations with the polyphenolic content were linear, except for the Efficient Concentration (EC20) parameter, whose relation was better described by a hyperbolic equation

Effetto dei poliaspartati sulla stabilità tartarica e sul colore dei vini rossi

La stabilizzazione tartarica dei vini può essere ottenuta asportando una parte del potassio e/o l'acido tartarico presenti o con l'aggiunta di additivi (acido metatartarico, gomme di cellulosa, mannoproteine) in grado di impedire la formazione e/o l'accrescimento dei cristalli di bitartrato di potassio, principale responsabile della comparsa di precipitati in bottiglia. Il presente lavoro ha riguardato lo studio dell'efficacia stabilizzante di nuove molecole: i poliaspartati (PASPs) su vini rossi. Lo studio aveva, inoltre lo scopo di verificare se, dopo l'aggiunta o durante la conservazione in bottiglia, l'apporto di queste molecole determini intorbidamento e/o perdita di colore nei vini rossi. I risultati evidenziano che i PASPs possiedono interessanti proprietà stabilizzanti nei confronti delle precipitazioni tartariche, simili a quelle dell'acido metatartarico. La presenza di PASP nei vini rossi non ha determinato perdite di antociani totali o modificazioni dei parametri cromatici (intensità e tonalità) né subito dopo l'aggiunta, né durante la conservazione. In un solo vino analizzato, subito dopo l'aggiunta di PASP (controllo dopo 48 ore), si è osservato un leggero aumento della torbidità nella tesi trattata. L'effettuazione di una chiarifica con bentonite (40 g/hL) prima dell'aggiunta del PASP ha consentito di evitare l'intorbidamento del vino