Grape stems are an abundant by-product of winemaking and a promising source of phenolic antioxidants representing an underutilized biomass within the circular economy. Seven Vitis vinifera L. cultivars were analysed by HPLC DAD, with Merlot (Me), Cabernet Sauvignon (CS) and Italian Riesling (IR) identified as the richest sources. This comparative screening provided the basis for a multi-index optimization of extraction. A 2³ full factorial design (ethanol 30–60% v/v; 30–80 min; 25–65 °C) was used for optimization. The optimal green conditions—60% ethanol, 80 min, 65 °C—yielded 1.860 mg/g CA, 1.098 mg/g Q-gluc and 0.409 mg/g Q-glc, with the Merlot stems showing the highest extraction efficiency and Merlot consistently outperforming the other varieties. Kinetic modeling using an unsteady state diffusion model showed excellent agreement (R² ≈ 0.99, RMS < 2%), suggesting a leaching-diffusion mechanism. The thermodynamic parameters confirmed an endothermic, spontaneous and irreversible process with ΔH° between 19.5 and 36.6 kJ/mol, ΔS° between 69.1 and 131.6 J/molK and ΔG° between −1.1 and −9.2 kJ/mol, depending on the compound and grape stem variety. This study shows that grape stems can be efficiently utilised as a sustainable source of phenolic antioxidants, with potential applications in the production of functional foods and dietary supplements. This integration highlights the novelty of the study and supports the valorization of grape stems in the framework of sustainability and the circular economy.

The oxidative degradation of anthocyanins in red wine was investigated under controlled conditions using hydroxyl radicals generated in the presence of Cu (II) as a catalyst. A full factorial experimental design with 23 replicates was used to evaluate the effects of hydrogen peroxide concentration, catalyst dosage, and reaction temperature on anthocyanin degradation over a fixed time. Statistical analysis (ANOVA and multiple regression) showed that all three variables and the main interactions significantly affected anthocyanin loss, with temperature identified as the most influential factor. The combined effects were described by a first-order polynomial model. The activation energies for degradation ranged from 56.62 kJ/mol (cyanidin-3-O-glucoside) to 40.58 kJ/mol (peonidin-3-O-glucoside acetate). Increasing the temperature from 30 °C to 40 °C accelerated the degradation kinetics, almost doubled the rate constants and shortened the half-life of the pigments. At 40 °C, the half-lives ranged from 62.3 min to 154.0 min, depending on the anthocyanin structure. These results contribute to a deeper understanding of the stability of anthocyanins in red wine under oxidative stress and provide insights into the chemical behavior of derived pigments. The results are of practical importance for both oenology and viticulture and support efforts to improve the color stability of wine and extend the shelf life of grape-based products.

This study focused on optimizing key extraction parameters (ethanol concentration, temperature, and time) to enhance the extraction of hydroxycinnamic acids from A. graveolens leaves, applying a replicated 2³ full factorial design. The experimental results demonstrated that extraction conditions significantly influenced the yield of hydroxycinnamic acids. The optimum conditions were 50% ethanol for 80 min at 50 °C, yielding 103.75 µg/g of chlorogenic acid (ChA), 6.05 µg/g of ferulic acid (FA), and 2.19 µg/g of sinapic acid (SA). Therefore, the extract obtained with 50% ethanol showed the highest levels of polyphenols, flavonoids, and antioxidant potential, highlighting its suitability for use in both food-related products and pharmaceutical formulations. Additionally, the applicability of different mathematical models (unsteady-state diffusion, parabolic diffusion, and power law models, as well as Ponomaryov’s and Elovich’s equations) to describe and better understand the kinetics of hydroxycinnamic acid extraction from dill leaves was evaluated. The fit of each kinetic model to the experimental data was assessed using the root mean square error and the coefficient of determination. Among the five kinetic models, the unsteady-state diffusion model and Ponomaryov’s equation provided the best fit, exhibiting the highest accuracy. The activation energy for the extraction process was determined to be 5.85, 6.46, and 7.59 kJ/mol for ChA, FA, and SA, respectively. The extraction of hydroxycinnamic acids from dill leaves was found to be endothermic, irreversible, and spontaneous.

The effects of temperature, time, and solvent concentration on the yield of bioactive compounds (BCs) with cytotoxic activity against three cell lines (Hep2c, RD, and L2OB) from Erica carnea L., as well as their influence on kinetic and thermodynamic parameters (enthalpy, entropy, and free energy), were investigated. The extract obtained at 30% ethanol, 50 °C, and 80 min showed the highest cytotoxic activity with IC₅₀ values of 14.29, 13.93, and 22.23 µg/mL, respectively. The kinetics of BC extraction with cytotoxic activity was better described by the unsteady-state diffusion model compared to the Ponomarev model. The activation energy obtained was in the range of Ea = (4.92–26.57) kJ/mol. The thermodynamic parameters under transition theory at 50 °C were ∆S* = (−220.22)–(−285.15) J/Kmol, ∆H* = (2.24–23.88) kJ/mol, and ∆G* = (94.34–96.30) kJ/mol, indicating that the extraction of BCs with cytotoxic activity against the three cell lines is an irreversible and endothermic process. In addition to cytotoxic activity, the extracts demonstrated strong antioxidant activity (e.g., DPPH IC₅₀ = 16.55 µg/mL) and antibacterial activity against multiple bacterial strains. Five antioxidant assays were applied, along with tests against eight bacterial strains for antibacterial activity. These findings suggest that Erica carnea L. is a promising natural source of multifunctional bioactive compounds with therapeutic potential.

Erica carnea L. has recently gained attention as a promising natural source of antioxidants suitable for food and beverage applications. This study aimed to obtain an antioxidant-enriched extract by optimizing the key extraction variables. A full factorial design was used to evaluate the effects of ethanol concentration, extraction time, and temperature, followed by validation through multiple antioxidant assays, including DPPH, ABTS, hydroxyl radical scavenging, lipid peroxidation inhibition, and metal chelation. The most efficient extraction was achieved at 30% ethanol, 120 min, and 50 °C, yielding IC₅₀ values of 18.42 μg/mL (LP), 15.04 μg/mL (DPPH), 5.14 μg/mL (MC), 11.28 μg/mL (OH), and 10.06 μg/mL (ABTS), in agreement with the model predictions. Extraction kinetics were described using an unsteady-state diffusion model, supported by low root mean square (RMS) values and high coefficients of determination. Thermodynamic analysis indicated an irreversible, endothermic process, highlighting the energetic requirements for phenolic release from plant tissue. The combined statistical and kinetic approach provides a clearer understanding of how process variables influence antioxidant recovery. In addition to strong antioxidant activity, the optimized extract showed measurable cytotoxic and antibacterial effects. Overall, these findings highlight E. carnea as a valuable material for developing antioxidant-rich formulations, with extraction efficiency governed by predictable kinetic and thermodynamic behavior.

Plum fruits are a valuable raw material to produce fermented beverages and a source of phenolic compounds with antioxidant properties. However, information on changes in phenolic composition during plum wine production is still limited. In this study, the evolution of phenolic compounds and antioxidant capacity during maceration and fermentation of wine from the ‘Stanley’ cultivar was investigated. Total phenolics, flavonoids, anthocyanins, and antioxidant capacity were determined spectrophotometrically, while individual compounds were identified by HPLC–DAD analysis. Eleven phenolic compounds were detected, including anthocyanins, hydroxycinnamic acids, and flavonols. Neochlorogenic acid, cyanidin-3-rutinoside, and rutin were the predominant compounds in fruits and wines. Phenolic content in plum skin was more than twofold higher than in whole fruit (445.20 vs. 198.32 mg GAE/100 g FW), with markedly higher anthocyanins (180.08 vs. 36.73 mg CGE/100 g FW), while juice showed much lower levels (89.32 mg GAE/L and 1.08 mg CGE/L). Maceration increased phenolic content and antioxidant activity, whereas fermentation led to a gradual decrease in most compounds, likely due to polymerization and degradation reactions. The wine produced contained 10.80 ± 0.15% (v/v) ethanol. Principal component analysis differentiated samples according to phenolic profile and fermentation stage.