Response surface methodology (RSM) was used to optimize the extraction of phenolics from pericap of Myrtus communis using ultrasound-assisted extraction (UAE). The results were compared with those obtained by microwave-assisted extraction (MAE) and conventional solvent extraction (CSE) methods. The individual compounds of the optimized extract obtained by UAE were identified by ultra-high-performance liquid chromatography coupled with diode array detection and electrospray ionization mass spectrometry (UHPLC-DAD-ESI-MSⁿ). The yield of total phenolic compounds (TPC) was affected more significantly by ethanol concentration, irradiation time, liquid solvent-to-solid ratio (p < 0.0001) and amplitude (p = 0.0421) and optimal parameters conditions set by the RSM model were 70% (v/v), 7.5 min and 30%, respectively. The experimental yield of TPC (241.66 ± 12.77 mg gallic acid equivalent/g dry weight) confirmed the predicted value (235.52 ± 9.9 mg gallic acid equivalent/g dry weight), allowing also to confirm the model validity. Under optimized conditions, UAE was more efficient than MAE and CSE in extracting antioxidants, which comprised mostly myricetin glycosides. Globally, the present work demonstrated that, compared to MAE and CSE, UAE is an efficient method for phenolic extraction from M. communis pericarp, enabling to reduce the working time and the solvent consumption.

The aim of this work was to optimize the conventional parameters for the extraction of phenolic compounds from potato (Solanum tuberosum L.) peels (PP). A central composite design (CCD) was used to establish the impacts of ethanol concentration (%), extraction time (min), and liquid/solid ratio (mL/g). The optimal experimental conditions that maximized extraction were ethanol at a concentration of 80% (v/v) for a time of 150 min with a ratio of 1 g/30 mL. Under optimal conditions, the total phenolic content (TPC) and the total flavonoid content (TFC) were 204.41 ± 8.64 mg GAE/100 g DW and 21.47 ± 0.76 mg QE/100 g DW, respectively. The PP extract had a potent antioxidant capacity tested by phosphomolybdate and DPPH assays with IC₅₀ of 10.65 ± 0.21 and 179.75 ± 3.18 µg/mL, respectively. Furthermore, by fortifying yogurt with PP as a natural ingredient, an improvement ofits physical, nutritional, antioxidant, and sensorial qualities was attempted in this study. The yogurts formulated with PP revealed significantly higher (p ≤ 0.05) TPC, TFC, and antioxidant capacity in comparison with the control sample. In addition, the sensory evaluation showed that the yogurts enriched with PP were preferred over the control yogurt. The results indicate that PP can be considered an interesting byproduct since it can improve the nutritional, bioactive, and sensorial profile of yogurt, highlighting that PP, due to its high phenol content, can substantially improve the antioxidant effect of the new formulated yogurt.

Solanum melongena L., also known as eggplant, is a widely consumed vegetable and it is well-known for its beneficial antioxidant properties, due to phenolic compounds. In this work, the influence of different cooking procedures on the content of chlorogenic acid was evaluated on eggplant samples of different geographic origin by high-performance liquid chromatography (HPLC). An easy and quick extraction procedure with 50% methanol as the extraction solvent was optimized for the first time by means of a design-of-experiment and applied to heat treated samples of eggplant. The antioxidant capacity of eggplant extracts was also evaluated by using the ABTS assay and it was correlated with the data obtained by the HPLC method. The content of chlorogenic acid was different in each heat-treated eggplant sample and it depended on the temperature applied during the cooking procedure. In particular, an increase of chlorogenic acid content with rising temperature was observed. Conversely, a very high temperature (250 °C) caused a decrease of chlorogenic acid amount. The influence of storage on the content of chlorogenic acid was also monitored. While the level of chlorogenic acid in fresh samples decreased during four weeks of storage, an increase in its content in heat treated eggplant was observed within the same period. Multivariate data analysis was used to classify eggplant samples into different groups, according to the country of origin and heat treatment procedure. This study provides new insights to preserve the antioxidant properties of eggplant phenolics during different thermal and storage treatments in order to highlight their health promoting effects.

The use of Nigella seeds in the food, pharmaceutical, and cosmetic fields is common, since the iniquity and the virtues of these plants are directly related to their characteristic phytochemical composition. This investigation focused on the comparative study of the botanical aspect, phenolic profile, and in vitro and in vivo biological activities of Nigella sativa L. (NS) and Nigella damascena L. (ND) seeds. The macro- and micro-morphological properties of these seeds were studied, and the key dissimilarities between them were clearly illustrated. The phytochemical contents and phenolic profiles were determined, and the in vitro antioxidant activity was assessed using four methods. The in vivo antioxidant and biochemical parameters of the blood of supplemented mice were determined. The results of the macro- and micro-structure analysis revealed differences between the two plants. Here, ND is characterized by higher phytochemical contents and the best antioxidant activities. The HPLC analysis indicated the presence of nine compounds, namely seven phenolic acids, particularly hydroxybenzoic and caffeic acids, and two flavonoids. The administration of ND extract to mice for 21 days at a concentration of 500 mg/kg allowed a substantial amelioration of plasma antioxidant properties. In addition, the extracts ameliorate blood parameters (cholesterol, triglycerides, glycemia, and urea). Furthermore, the antimicrobial activity of extracts demonstrated their effects on Staphylococcus and Aspergillus. Nigella seeds, in particular ND, expressed considerable in vitro antioxidant properties and demonstrated significant amelioration of mice blood properties. Consequently, these species can serve as a valuable source of compounds with various applications.