Optimization of Conventional Extraction Parameters for Recovering Phenolic Compounds from Potato (Solanum tuberosum L.) Peels and Their Application as an Antioxidant in Yogurt Formulation.

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

Essential oils composition, antibacterial and antioxidant activities of hydrodistillated extract of Eucalyptus globulus fruits

Aromatic plants and their essential oils have been used since antiquity in flavor and fragrances, as condiments or spices, in medicines, as antimicrobial/insecticidal agents, and to protect stored products. The present study was undertaken: to determine (:) the chemical composition of essential oils extract from Eucalyptus globulus (E. globulus) fruits, using Gas-Chromatography coupled with Mass Spectrometry (GC/MS) method, to examine their antioxidant activity (DPPH', reducing power and lipid peroxidation inhibition assays) compared to that of Butylated hydroxyanisole (BHA) standard, and to estimate their antibacterial effects against reference pathogenic strains: Staphylococcus aureus (S. aureus), Bacillus subtilis (B. subtilis), Listeria innocua (L. innocua), Escherichia coli (E. coli), Pseudomonas aerugenosa (P. aerugenosa), compared to that of two antibiotics (tetracycline and gentamicin). Twenty eight volatile compounds were identified, with the predominance of sesquiterpenes and oxygenated sesquiterpenes compounds (61.2%). The results of the antioxidant activities (DPPH scavenging activity, reducing power and inhibition of lipid peroxidation activity) of essential oils extract revealed weak activities with IC50 values of 27.0 +/- 0.2 mg mL(-1),32.9 +/- 1.8 mg mL(-1) and 4.9 +/- 0.2 mg mL(-1), respectively; as compared to those of Butylated hydroxyanisole (BHA) standard that were about 0.05 +/- 0.0 mg mL(-1), 0.03 +/- 0.0 mg mL(-1) and 0.51 +/- 0.2 mg mL(-1), respectively. The antibacterial activity shows an inhibition effect of essential oils extracts against all the tested bacteria with MIC of 3 and 4 mg mL(-1). A bactericidal effect is observed, with MBC varying between 3.6 and 9.0 mg mL(-1), which demonstrates the sensibility of all tested bacteria to the essential oils of E. globulus fruits

Improvement of thermo-resistance and quality of soybean oil by blending with cold-pressed oils using simplex lattice mixture design

Soybean oil is the most consumed oil worldwide due to its cheapness but presented a weak thermo-resistance due to its richness in poly-unsaturated fatty acids. This study aims to improve the thermo-stability of refined soybean oil by blending it with some cold-pressed oils. For this, cold-pressed and soybean oils were firstly characterized (K232, K270, acidity, peroxide value, iodine value, induction time, phenolic contents, and antioxidant activity). Then, binary blends of each cold-pressed oil (30%) with soybean oil (70%) were analyzed before and after heat treatment (170 °C for 10 h/day for 5 days) followed by the application of the simplex lattice mixture design in order to optimize the combination of the three best cold-pressed oils. The changes in fatty acid profiles were assessed by gas chromatography (GC-FID). The results revealed that soybean oil presented the best physicochemical traits, while cold-pressed oils expressed high levels of phenolic contents and antioxidant activities. From the six binary oil blends, soybean oil mixed with lentisk, sesame, or almond oils were selected for their best thermo-stability. The simplex lattice mixture design, applied for these three chosen oils, indicated that the combination of soybean oil (70%) with lentisk and sesame oils (17.7 and 12.3%, respectively) was considered the optimal blend that gives the maximal thermo-stability improvement to soybean oil. GC-FID analysis showed that fatty acids, particularly linoleic and linolenic acids, were more conserved after heat-treatment in optimal oils blend than soybean oil. This study clearly demonstrated that lentisk and sesame oils enhanced the thermo-resistance of soybean oil, and the findings of this study could be used as an integrated model in oil and fat industries