Effects of extraction solvents on phenolic contents and antioxidant activities of Tunisian date varieties (Phoenix dactylifera L.)

peer reviewedSecond-grade dates (Phoenix dactylifera L.), with hard texture, from six Tunisian cultivars were analysed for their composition and antioxidant activities. Results showed predominance of total sugars and a relatively low content of protein, fat andash. On the other hand, optimisation of extraction of antioxidant was carried using five different solvents. The highest level of phenolic compounds for all dates varieties was found in the 70% acetone extract. This level ranged from 199.43 to 576.48 mg of GAE/100 g fresh weight. However, extraction into 50% methanol gave the highest antioxidant activity from 89.55 to 109.67 mg equivalents of ascorbic acid/g fresh weight. For both two olvents, Bejo exhibited the highest phenolic content and total antioxidant activity, while Baydh El Hamam presented the owest. A positive linear correlation between total antioxidant activity and phenolic contents was observed (R2 = 0.83; R2 = 74 for acetone/H2O and methanol/H2O, respectively). The antioxidant activity of acetone/H2O and methanol/H2O extracts was carried using DPPH radical-scavenging activity and reducing power. These results showed that dates had strongly scavenging activity on DPPH reaching 90.12% in methanol/H2O from Deglet Nour. Whereas, acetone/H2O showed the best reducing power which Bejo was significantly higher than the other varieties. This study demonstrates the potential antioxidant activity with Tunisian date, that we can use these natural extracts as food additives in replacement of synthetic compounds

Runge-Kutta-Nyström Pairs of Orders 8(6) with Coefficients Trained to Perform Best on Classical Orbits

In this study, we consider eight stages per step family of explicit Runge-Kutta-Nyström pairs of orders eight and six. The pairs from this family effectively use eight stages for each step. The coefficients provided by such a method are much less than the number of non linear order conditions required to be solved. Thus, we traditionally apply various simplified assumptions in order to address this drawback. The assumptions taken in the family we consider here deliver a subsystem where all the coefficients are evaluated successively and explicitly with respect to five free parameters. We train (adjust) these free parameters in order to derive a certain pair that outperforms other similar pairs of orders 8(6) in Keplerian type orbits, e.g., Kepler, perturbed Kepler, Arenstorf orbit, or Pleiades. Differential evolution technique is used for the training. The pair that we finally present offers about an additional digit of accuracy in a variety of orbits. © 2022 by the authors. Licensee MDPI, Basel, Switzerland

Badanie struktury mieszania w zbiorniku z mieszadłem w systemie wielowirnikowym z czteropłatkowymi wirnikami Rushtona

The effect of multiple Rushton impellers configurations on hydrodynamics and mixing performance in a stirred tank has been investigated. Three configurations defined by one, two and three Rushton impellers are compared. Results issued from our computational fluid dynamics (CFD) code are presented here concerning fields of velocity components and viscous dissipation rate. These results confirm that the multi-impellers systems are necessary to decrease the weaken zones in each stirred tanks. The experimental results developed in this work are compared with our numerical results. The good agreement validates the numerical method.W pracy badano efekt konfiguracji wielołopatkowych wirników Rushtona na hydrodynamikę i skuteczność mieszania w zbiorniku z mieszadłem. Porównano trzy konfiguracje mieszadła, zdefiniowane przez jeden, dwa lub trzy wirniki Rushtona. W artykule zaprezentowano wyniki, uzyskane przy użyciu własnego oprogramowania do obliczeń dynamiki płynów (CFD), dotyczące składników pól prędkości i szybkości dyssypacji lepkościowej. Wyniki te potwierdzają, że systemy wielowirnikowe są niezbędne dla zmniejszenia stref zubożonych w każdym zbiorniku z mieszadłem. Wyniki eksperymentalne, uzyskane w tej pracy, są porównane z wynikami obliczeń numerycznych. Dobra zgodność wyników potwierdza przydatność metody numerycznej

Effect of processing conditions on phenolic compounds and antioxidant properties of date syrup

Commercial hydrolytic enzymes (pectinase and cellulase) were investigated for their influence on phenolics and antioxidant activities of date syrup. Content of total phenolics, flavonoids and carotenoids contents were determined spectrophotometrically. Polyphenols composition was examined using HPLC. Seven phenolic compounds (catechin, vanillic acid, caffeic acid, syringic acid, p-coumaric acid, ferulic acid and sinapic acid) were detected in all date syrup extracts. p-Coumaric acid was the major compound of all date syrup extracts, representing 49.223-63.397%. The antioxidant activity of date syrup was evaluated by various antioxidant assays, including total antioxidant, DPPH scavenging test, FRAP, hydrogen peroxide scavenging activity and metal chelating activity.Results showed that the date syrup prepared after extraction with pectinase and cellulase mixture gave the lowest phenolic and flavonoid contents. For same variety, date syrup prepared after extraction with pectinase and cellulase mixture gave the highest carotenoids amounts. The antioxidant activity, determined by several methods, was significantly affected by the extraction method as well as date varieties. In fact, the date syrup prepared after extraction with pectinase and cellulase mixture gave the lowest antioxidant activity. A good correlation between the antioxidant activity and total phenolic content and flavonoid was observed. The discovery of our research is very important to scientists as well as to the fruit-processing industry to produce juice and syrup with high antioxidant activity. © 2012 Elsevier B.V