Adem Gharsallaoui

Grape pomace represents an underexploited source of pectic polysaccharides whose properties are strongly influenced by extraction conditions. This study investigated the combined effects of acid type (citric acid or HCl), pH (1.5, 2.0 and 3.0), and temperature (55, 65 and 85 °C) on pectic fractions recovered from grape pomace using sequential ultrasound-assisted extraction followed by dynamic maceration. A 2 × 3 × 3 full-factorial design was applied, combining citric acid or hydrochloric acid, three pH values (1.5, 2.0 and 3.0) and three temperatures (55, 65 and 85 °C), resulting in 18 extraction conditions. The recovered fractions were characterized in terms of extraction yield, degree of esterification (DE), methoxyl content (MeO), anhydrouronic acid content (AUA), molecular weight (Mw), apparent viscosity, carbohydrate and protein contents, color, FTIR profile, total phenolic content (TPC) and antioxidant activity. Extraction yield ranged from 1.12 to 7.88%, with the highest recovery obtained using citric acid at pH 3.0 and 55 °C. DE varied markedly from 14.89 to 63.63%, with citric acid consistently yielding low-methoxyl fractions under all conditions, whereas HCl at pH 1.5 yielded high-methoxyl fractions. MeO varied accordingly from 1.66 to 7.65%, while AUA remained within a comparatively narrow range of 63.27–69.24%, close to that measured for commercial citrus pectin (67.21%). Molecular weight ranged from 22.7 to 607 kDa, and increasing extraction temperature generally reduced both Mw and apparent viscosity, indicating greater structural modification under harsher conditions. FTIR spectra confirmed the preservation of the characteristic pectic polysaccharide framework while revealing differences in the carboxyl and fingerprint regions among extraction conditions. The recovered fractions contained 180.22–310.78 mg glucose eq./g total carbohydrate and 8.56–32.83 mg BSA eq./g protein. Phenolic compounds were also retained, with TPC values of 9.50–14.29 mg GAE/g and ABTS IC₅₀ values ranging from 4.26 to 10.38 mg/mL. The factorial analysis demonstrated significant interactions among acid type, pH, and temperature for the main physicochemical and functional responses. Overall, the results demonstrate that these extraction variables can be adjusted to recover grape pomace pectic fractions with distinct esterification, molecular and antioxidant profiles.

This study aimed to develop bioactive pectin-based films incorporating Deverra tortuosa (D. tortuosa) essential oil (EO) nanoemulsions stabilized by sodium caseinate for potential active food packaging applications. EO nanoemulsions were incorporated into a pectin–maltodextrin matrix, and the resulting films were characterized for their thermal, morphological, antioxidant, and antimicrobial properties. Thermal analyses revealed an additional low-temperature mass loss in EO-loaded films, attributed to volatile oil constituents, while differential scanning calorimetry showed an endothermic transition at 171.9 °C associated with matrix reorganization and volatile release. Scanning electron microscopy (SEM) demonstrated increased surface heterogeneity and the formation of microcavities compared with EO-free films (F⁻). The incorporation of EO significantly enhanced antioxidant activity, with half-maximal inhibitory concentration (IC₅₀) values of 9.18 µg mL⁻¹ and 1.95 µg mL⁻¹ in 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays, respectively. In addition, the films exhibited antimicrobial activity against Escherichia coli, Salmonella enterica, and Listeria innocua, with minimum inhibitory concentrations ranging from 1.25 to 2.5 mg mL⁻¹. These results demonstrate that the incorporation of Deverra tortuosa EO nanoemulsions improves the functional properties of pectin-based films and supports their potential use as biodegradable active packaging materials.

Supercritical carbon dioxide extraction (SFE-CO₂) is an efficient and environmentally friendly process for extracting bioactive compounds from plant material. This investigation examined the combined effects of air-drying temperature of the leaves and SFE-CO₂ operating conditions on the extraction yield, volatile compound composition, and antimicrobial activity of Pistacia lentiscus leaf extracts. Extractions were performed at pressures ranging from 100 to 200 bar and temperatures ranging from 35 to 55 °C. Extraction yield increased with extraction pressure and temperature, while fresh leaves yielded the highest extract, highlighting the importance of pretreatment on extractability. Chemical analysis revealed notable variations in monoterpene hydrocarbons, oxygenated monoterpenes, sesquiterpene hydrocarbons, and oxygenated sesquiterpenes depending on drying temperature and extraction parameters, confirming the high sensitivity of the volatile compound composition to processing conditions. Response surface methodology (RSM) was used to optimize process variables in order to enhance antimicrobial activity. The extracts inhibited both bacterial and fungal strains, confirming that the extraction conditions exert a direct influence on biological properties. The quadratic model identified the optimal combinations of drying and supercritical CO₂ extraction parameters, thereby providing a rational strategy to maximize the antimicrobial potency of P. lentiscus extracts. Overall, controlling pretreatment and supercritical extraction conditions allows for targeted modulation of chemical composition and bioactivity, thereby promoting the development of natural antimicrobial agents and valuable functional components.

Excessive application of chemical preservatives has raised increasing concerns regarding food safety and human health, prompting the search for safer natural alternatives. Lavender essential oil (LEO), a plant-derived antimicrobial agent, has been considered a promising substitute for synthetic preservatives, but its high volatility and poor water solubility limit its practical application. In this study, LEO nanoemulsions were fabricated via high-pressure homogenization using sodium caseinate (SC) and tea polyphenols (TPs) as composite emulsifiers. The preparation process was optimized using a three-factor, three-level orthogonal design, and the physicochemical properties, storage stability, and antibacterial activity were systematically investigated. The optimal preparation conditions were determined as an SC/TP mass ratio of 2:1, homogenization pressure of 70 MPa, and 7 homogenization cycles. The optimized nanoemulsion exhibited a droplet size of 130–210 nm, zeta potential of −30.89 mV, and encapsulation efficiency of 98.61%, with typical shear-thinning behavior and excellent storage stability. The percentage of free LEO remained below 7.5% within 15 days, indicating high stability, and the release behavior followed a zero-order kinetic model. The prepared nanoemulsion showed significant antibacterial activity against Staphylococcus aureus and Escherichia coli, with a minimum inhibitory concentration (MIC) of 62.5 μg/mL for both strains. This study confirms that the SC/TP composite interface can effectively stabilize LEO nanoemulsions, providing a theoretical basis for the development of natural and efficient food preservatives.

Interactions between resveratrol and biological or carrier systems play a key role in determining its bioavailability, stability, and delivery performance. These interactions involve proteins, lipids, cyclodextrins, nucleic acids, polysaccharides, and other formulation matrices, and are governed by noncovalent forces such as hydrogen bonding, hydrophobic interactions, π–π stacking, and desolvation effects. This review examines how complementary spectroscopic, calorimetric, structural, and computational techniques are used to characterize resveratrol interactions. Fluorescence, UV–visible spectroscopy, circular dichroism, FTIR, NMR, ITC, DSC, X-ray diffraction, molecular docking, and molecular dynamics simulations are discussed according to their contribution to binding analysis, conformational assessment, thermodynamic interpretation, structural organization, and complex stability. By integrating these approaches, this review provides a technique-oriented framework for understanding resveratrol binding and guiding the development of more stable resveratrol-based carrier systems and bioactive formulations.