Les composés phénoliques des raisins (étude du potentiel qualitatif et des procédés émergeants d'extraction)

Ce travail porte sur l amélioration de l extraction des composés phénoliques à partir des raisins tout au long de la chaîne de la vinification en rouge. La qualité des vins rouges est en grande partie déterminée par les composés phénoliques. Parmi les composés phénoliques, les anthocyanes, qui sont responsables de la couleur, et les tanins, à l origine de la sensation d astringence. Pour augmenter la quantité des composés phénoliques présents dans le vin, un développement des procédés permettant d améliorer la diffusion des composés phénoliques durant la vinification en rouge doit être mis en jeu. Nous avons entamé notre étude par un suivi de la maturité phénolique des raisins rouges appartenant à différentes parcelles de la société château KSARA localisées dans la vallée de la Békaa tout en se servant des méthodes Glories (1&2) et ITV. Quant à l amélioration de l extractibilité des composés phénoliques durant la vinification en rouge, différents prétraitements ont été appliqués dans le but d améliorer la diffusion de ces composés. Parmi ces procédés, les technologies suivantes ont été abordées dans notre étude: les électrotechnologies (CEP), les ultrasons, le chauffage modéré, le traitement enzymatique, la macération préfermentaire à froid et la thermovinification. Ces techniques permettent d endommager ou de fragiliser les membranes et/ou parois cellulaires facilitant ainsi la libération du contenu cellulaire vers le milieu extérieur. Les cinétiques d extraction des composés phénoliques ont pu être modélisées par le modèle empirique de Peleg et le modèle cinétique simplifié afin d estimer les rendements d extraction. De plus, dans ce travail, l accent a été mis sur les propriétés antiradicalaires et antimicrobiennes des composés phénoliques extraits de différentes variétés de raisins fournis par la société Château KSARA. Pour valoriser les co-produits de la vinification, le chauffage ohmique pulsé (COP) a été appliqué sur le marc du raisin dans le but d améliorer l extraction de ses composés phénoliques. L'optimisation du choix de la date des vendanges et l'amélioration des procédés d extractions des composés phénoliques durant la vinification en rouge, pourraient nous conduire à élaborer un vin d'une meilleure qualité. Ce travail étant effectué, il sera intéressant comme projet à venir de valider ces différents pré-traitements à grande échelle pour une perspective d application industrielle.This study focuses on improving the extraction of phenolic compounds from grapes throughout the chain of red winemaking. The quality of wine is mainly determined by the phenolic compounds. From these phenolic compounds, the anthocyanins, which are responsible of the color and tannins, the responsible of the astringency. In order to increase the amount of phenolic compounds present in wine, a development of methods used to improve the extraction of phenolic compounds during the red vinification should be discussed. We began our study by using two methods Glories (1&2) and ITV to monitor the phenolic maturity of red grapes grown in the vineyards in the province of Bekaa-Château KSARA S.A.L. Whereas for the improvement of the extractibility of phenolic compounds during the vinification, different pre-treatments were applied in order to ameliorate the diffusion of these compounds. Among these process, the following technologies were discussed in our study: the electrotechnologies (PEF), the ultrasound, the moderate heat treatment, the enzymatic treatment, the cold maceration and the thermovinification. These techniques are able to weaken the cell walls and facilitate the diffusion of grape s phenolic compounds during vinification. Peleg s equation and the simplified kinetic model were shown to be suitable for describing the extraction kinetics for phenolic compounds and for the estimation of the extraction yield of polyphenols. Furthermore, in this study, the antiradical and antimicrobial activities of phenolic compounds extracted from grapevine varieties of Château KSARA-Bekaa-Lebanon were analyzed. To valorize the by-products of the vinification, the pulsed ohmic heating (POH) was applied on the grape pomace in order to ameliorate the extraction of the phenolic compounds. The optimization of the choice of the harvesting date and the amelioration of the extraction of phenolic compounds during the red vinification, will conduce to elaborate a high quality of wine. After this study, it will be interesting to validate the different pre-treatments at large scale for a perspective of an industrial application.COMPIEGNE-BU (601592101) / SudocSudocFranceF

The effect of aeration conditions, characterized by the volumetric mass transfer coefficient KLa, on the fermentation kinetics of Bacillus thuringiensis kurstaki

The aeration is a key factor for Bacillus thuringiensis growth, sporulation and δ-endotoxins production. The objective of our work was to study the effect of aeration on the fermentation kinetics of Bacillus thuringiensis kurstaki (Btk), cultivated in a cereal milling byproduct (CMB) mono-component medium, in order to improve the δ-endotoxins productivity. Aeration conditions were systematically characterized by the volumetric mass transfer coefficient KLa. In the 6% CMB culture medium, different values of the maximal specific oxygen uptake rate were obtained at different values of KLa. For KLa of 7.2 h−1, the growth was inhibited and the sporulation was defective. There was a linear increase of the average specific growth rate and faster sporulation and liberation of spores and δ-endotoxins crystals when KLa was increased between 13.3 h−1 and 65.5 h−1. Similar kinetic was observed in cultures performed at KLa equal to 65.5 h−1 and 106.2 h−1. The highest toxins productivity of 96.1 mg L−1 h−1 was obtained in the 9% CMB culture medium for KLa of 102 h−1. It was possible to track the evolution of the bacterial cells between vegetative growth, sporulation and liberation of mature spores by following the variation of the CO2 percent in the effluent gas

Systematic and Empirical Study of the Dependence of Polyphenol Recovery from Apricot Pomace on Temperature and Solvent Concentration Levels

This work aims to study the impact of solvent mixture (between 0 and 50% ethanol/water mixture) and temperature (between 25°C and 75°C) levels on the solid-liquid extraction of phenolic compounds (quantity and bioactivity) from apricot pomace. Results show that the mean augmentation of 1% ethanol in the range [0–12%] enhances by three times the extraction of polyphenols compared to the same augmentation in the range [0–50%]. Similarly, the mean augmentation of 1°Celcius in the range [0–25°Celcius] enhances by two times the extraction of polyphenols compared to the same augmentation in the range [0–75°Celcius]. Moreover, 1% of ethanol exhibited a greater impact on the phenolic compound extraction than 1°Celsius. The response surface methodology showed that the optimal extraction condition was reached with 50% ethanol/water at 75°C giving a total phenolic content (TPC) of 9.8 mg GAE/g DM, a flavonoids content (FC) of 8.9 mg CE/g DM, a tannin content (TC) of 4.72 mg/L, and an antiradical activity (AA) of 44%. High-performance liquid chromatography (HPLC) analysis showed that polyphenols were influenced by the selectivity of the solvent as well as the properties of each phenolic compound. Apricot pomace extracts could therefore be used as natural bioactive molecules for many industrial applications

Exhausted Grape Seed Residues as a Valuable Source of Antioxidant Molecules for the Formulation of Biocompatible Cosmetic Scrubs

Grape seed of Obeidi, a white Lebanese autochthonous variety, was previously tested in different studies as a valuable source of bioactive molecules such as polyphenols, oils, and proteins by means of extraction procedures for the development of cosmetic and therapeutic products. However, an un-valorized, exhausted grape seed residue remains as "secondary waste" after the extraction processes. In this study, the exhausted seeds have been further exploited to produce cosmetic scrubs capable of releasing antioxidant molecules during the exfoliation process, in accordance with the principles of the circular economy and going toward a zero-waste process. The deep characterization of the exhausted seeds confirmed the presence of antioxidant phenolic molecules including gallic acid, catechins and protocatechuic acid (0.13, 0.126, and 0.089 mg/g of dry matter DM), and a high phenolic content (11.85 mg gallic acid equivalents (GAE)/g of dry matter (DM)). Moreover, these residues were shown to possess a sandy texture (Hausner ratio (HR): 1.154, Carr index (CI): 0.133, and angle of repose: 31.62 (& DEG;) degrees), similar to commercial natural exfoliants. In this respect, exhausted Obeidi grape seed residues were incorporated at increasing concentrations (0.5, 1, 1.5, and 2% w/w) in a cosmetic scrub, and stored for 5 weeks at 4, 25, and 50 & DEG;C for stability testing. All tested scrub formulations exhibited good spreadability with a spread diameter of 3.6-4.7 cm and excellent physical stability, as no phase separation or color change were observed after four cycles of heat shock at 4 and 50 & DEG;C. Finally, an in vivo skin irritation test showed that the scrub enriched with 1.5% of exhausted Obeidi grape seed residues was the most promising formulation, as it possessed a high amount of phenolic molecules (0.042 & PLUSMN; 0.001 mg GAE/mL of scrub) and good stability and could be safely applied to the skin with no irritation phenomena. Overall results underlined that exhausted grape seed residues can be transformed into promising systems for both physical and chemical exfoliation, thus confirming the importance of the effective exploitation of agro-industrial by-products for the development of high value cosmeceutics towards a more sustainable and zero-waste approach

Optimization of Polyphenols' Recovery from Purple Corn Cobs Assisted by Infrared Technology and Use of Extracted Anthocyanins as a Natural Colorant in Pickled Turnip

An ecofriendly extraction technology using infrared (IR) irradiation Ired-Irrad® was applied to purple corn cobs to enhance polyphenol recovery for the first time. The IR extraction efficiency was compared to that of the water bath (WB) method. Response surface methodology (RSM) using a central composite design was conducted to determine the effect of the experimental conditions (extraction time and treatment temperature) and their interactions on the total polyphenol and anthocyanin yields. Optimal extraction of total phenolic compounds (37 mg GAE/g DM) and total monomeric anthocyanins (14 mg C3G/g DM) were obtained at 63 °C for 77 min using IR as an extraction technique and water as a solvent. HPLC revealed that the recovery of peonidin 3-O-glucoside and cyanidin 3-O-glucoside was enhanced by 26% and 34%, respectively, when using IR. Finally, purple corn cobs' spray-dried extract was proven to be an important natural colorant of pickled turnip. It offers great potential for use as a healthy alternative to the carcinogenic rhodamine B synthetic dye, which was banned

Comparative Study between Ethanolic and β

Peach byproducts are often regarded as food waste despite their high content in health-promoting components. Amongst the latter, polyphenols are bioactive molecules with significant health benefits. The present study investigated an eco-friendly and cost-effective method using a GRAS food additive, β-cyclodextrin (β-CD), for the recovery of polyphenols from peach pomace. β-CD assisted extraction of polyphenols was compared to that of conventional solvent (ethanol) extraction at the same concentrations (10 mg/mL, 20 mg/mL, 30 mg/mL, 40 mg/mL, and 50 mg/mL) in terms of quality (antiradical activity) and quantity. The extract obtained by 50 mg/mL β-CD assisted extraction showed the highest polyphenol (0.72 mg GAE/g DM) and flavonoid (0.35 mg catechin/g of DM) concentrations as maximal antiradical activity (6.82%) and a noted antibacterial activity. Our results showed the competitiveness of β-CD assisted extraction to recover a high quantity and quality of polyphenols from peach pomace suggesting β-CD as a green alternative method for phenolic extraction

The International Natural Product Sciences Taskforce (INPST) and the power of Twitter networking exemplified through #INPST hashtag analysis

Background: The development of digital technologies and the evolution of open innovation approaches have enabled the creation of diverse virtual organizations and enterprises coordinating their activities primarily online. The open innovation platform titled "International Natural Product Sciences Taskforce" (INPST) was established in 2018, to bring together in collaborative environment individuals and organizations interested in natural product scientific research, and to empower their interactions by using digital communication tools. Methods: In this work, we present a general overview of INPST activities and showcase the specific use of Twitter as a powerful networking tool that was used to host a one-week "2021 INPST Twitter Networking Event" (spanning from 31st May 2021 to 6th June 2021) based on the application of the Twitter hashtag #INPST. Results and Conclusion: The use of this hashtag during the networking event period was analyzed with Symplur Signals (https://www.symplur.com/), revealing a total of 6,036 tweets, shared by 686 users, which generated a total of 65,004,773 impressions (views of the respective tweets). This networking event's achieved high visibility and participation rate showcases a convincing example of how this social media platform can be used as a highly effective tool to host virtual Twitter-based international biomedical research events

Thermomechanical process intensification for oil extraction from orange peels.

International audienceThe study investigated the intensification and improvement of oil extraction from orange peel through a thermomechanical process: the Instantaneous Controlled Pressure Drop (briefly D.I.C process). This process involves subjecting orange peel for a short time to steam pressure, followed by an instantaneous decompression to vacuum at 50 mbar. Central composite design was used to study the combined effects of processing steam pressure (1–7 bar; which corresponds to a temperature ranging between 100°C and 162 °C respectively), processing time (0.3 – 3.7 min.) and initial moisture content of orange peel before thermomechanical oil extraction (9.8 – 60.2 % on dry material basis). The quantitative analysis, have been undertaken on oil present in orange peels, after processing. Correlation analysis of the mathematical regression model indicated that quadratic polynomial model could be employed to optimize the extraction of oil from orange peel. From response surface plots, the three variables exhibited a linear effect with the strongest effect for the processing pressure. The optimum reaction conditions selected with response surface analysis were as follows: steam processing pressure: 6.6 bar, processing time: 3.68 min, initial moisture content: 53.6 % d.m basis. Under these conditions, experimental yield of orange peel oil was close to predicted value (99 %) calculated from the polynomial response surface model equation. A kinetic study indicated that extraction performed by D.I.C process is clearly quicker than conventional steam distillation method