Impact of freezing and drying preprocessing on pigments extraction from the brown seaweed «phyllaria reniformis» collected in algerian coast

Publication Scientifique

H. MOKRANE, N. GHALIAOUI, M. HAZZIT, M. HADJADJ, F-S OTMANI, S. TOUATI, H. SERIDI

Carpathian Journal of Food Science and Technology

Received:
5 January 2019
Accepted:
15 August 2020

ABSTRACT
Seaweeds are an excellent source of natural pigments such as chlorophylls
and carotenoids that exhibit several bioactive properties fully exploited in
food and health products. Due to the high sensitivity and the rapid
degradation of pigments, recent researches are now focusing on
development of efficient techniques for their extraction, while the sample
preprocessing as the main important step attracted less attention. The
objective of this study was the evaluation of the effect of freezing and drying
preprocessing on pigments quantity, quality and antioxidant activity of the
brown seaweed Phyllaria reniformis. Pigments were quantified using UVVisible spectrophotometry and fully characterized by reverse phase high
performance liquid chromatography (RP-HPLC). Phyllaria reniformis was
characterized by a high amount of pigments especially fucoxanthin. Based
on UV-visible spectrophotometry results, alga preprocessing before
extraction showed a high variability on pigments content. As shown by RPHPLC freezing preprocessing exhibited the most efficient pigment
extraction in term of quantity. While, drying preprocessing demonstrated
higher amount of β-carotene and pheophytin a. The highest and most
efficient antioxidant activities were obtained in the frozen samples. The
quality, quantity and antioxidant activities of Phyllaria reniformis pigments
extract was found to be deeply related to the preprocessing step

Keywords:
Preprocessing
Freezing
Drying
Phyllaria reniformis
Pigments


https://doi.org/10.34302/crpjfst/2020.12.3.6

Contribution à la valorisation des dattes (Deglet-Nour) dans la fabrication du fromage de chèvre

Publication Scientifique

N. FEDALA, M. MOKHTARI, L. MEKIMENE

Revue Agrobiologia

(2020), 10(1): 1918-28.

Reçu le 30/11/2019, Révisé le 09/06/2020, Accepté le 12/06/2020

Résumé
Description du sujet : Les progrès réalisés dans le domaine de la fabrication fromagère correspondent pour la
plupart aux efforts de recherche entrepris au cours du dernier siècle.
Objectifs : Formulation de fromages aux caractéristiques organoleptiques spécifiques, en combinant les bienfaits
du lait de chèvre et du fruit du dattier (Phoenix dactylifera L.).
Méthodes : Un fromage frais et un fromage à pâte pressée sont fabriqués. Les différentes analyses physicochimiques et microbiologiques sont réalisées pour le lait, et les fromages. L’analyse sensorielle est effectuée, les
dégustateurs ont été invités à noter leur préférence en utilisant des fiches de dégustation.
Résultats : L’EST est de 35 % pour les fromages frais et de 60 % pour les fromages à pâte pressée. La teneur en
G/S est de 42,85 % pour les fromages frais et de 38,33% pour les pâtes pressées. D’autre part, la teneur minimale
en protéines est de 25 % pour le fromage frais et de 31,35 % pour la pâte pressée. L’analyse microbiologique a
révélé l’absence de germe pathogène. La persistance de l’arôme des dattes est plus marquée pour les deux types
de dégustateurs.
Conclusion : Les fromages fabriqués présentent des caractéristiques organoleptiques spécifiques avec une
possibilité de les extrapoler en industrie laitière.

Mots clés : Deglet-Nour, lait de chèvre, produit du terroir, fromage.

Leaf organic content variation of 2 durum wheat genotypes under water stress by applying phytohormone (IAA)

Publication Scientifique

A. BENDJAMA , S. RAMDANI

African Journal of Agricultural Research

  Received: 05 May 2020   Accepted: 10 September 2020   Published: 31 October 2020

Abstract

Water stress is the most important problem in plant growth and development. Greenhouse trial is carried out on 2 durum wheat (Triticum durum Desf) genotypes (MBB and WAHA), to evaluate the effect of water stress on the biochemical content of leaves, and the possibility of reducing this effect by applying a growth regulator Indole-3-acetic acid (IAA) by seeds soaking and foliar spraying. Water stress causes a large accumulation of proline and soluble sugars and a decrease in the chlorophyll content of the leaves. The results obtained show that the effect of the hormone on the above-mentioned parameters is different according to the genotype and the mode of treatment, as well as the growth phase of the plant, without being able to promote application by soaking or spraying. The application of IAA has relatively reduced the effect of water stress by promoting the synthesis of proline and soluble sugars as osmotic regulators, and by increasing the chlorophyll content of the leaves. proline and soluble sugars concentrations showed negative and significant correlations with those of total chlorophyll. Our present study highlights some biochemical responses of plants to tolerate a water deficit and the possible involvement of exogenus application of IAA, as a phytohormone, in these regulatory mechanisms.

Key words: Triticum durum Desf, water stress, Indole-3-acetic acid (IAA), seed soaking, foliar spraying.

Proton transfer reaction confined within carbon nanotubes: Density functional theory and quantitative structure–property relationship analysis

Publication Scientifique

B. ACHOURI, Y. BELMILOUD, M. BRAHIMI

Reaction Kinetics and Mechanism

First Published September 18, 2019 Research Article

Abstract

In this work, we focus our attention on chemical reactions confined within carbon nanotubes. As a result of the confinement within carbon nanotubes, novel physical and chemical properties are found for the confined materials. We consider the feasibility of proton transfer inside carbon nanotubes. To do that, we have chosen formamide as the simplest real model for exhibiting the tautomerization in DNA. We have used the quantitative structure–property relationship method, based on geometry optimization and quantum chemical structural descriptors, to illustrate the potential of using the confined space inside carbon nanotubes, which will provide comprehensive information about carbon nanotubes. All calculations have been carried out using density functional theory quantum calculations with the B3LYP functional. The geometries optimized by the Gaussian program were transferred to the computer software DRAGON to calculate pertinent descriptors that could be used in the quantitative structure–property relationship model.

Keywords Proton transfercarbon nanotubesformamideDNAtautomerizationquantitative structure–property relationshipdensity functional theoryONIOM

https://doi.org/10.1177/1468678319864473

Electrocatalytic performance of Pt–Ni nanoparticles supported on an activated graphite electrode for ethanol and 2-propanol oxidation

Publication Scientifique

M-L. CHELAGHMIA, M. NACEF, H. FISLI, A-M. AFFOUNE, M. PONTIE, A. MAKHLOUF, T. DERABLA, O. KHELIFIand F. AISSAT

The Royal Society of Chemistry

Received 26th August 2020 , Accepted 26th September 2020

Abstract

Platinum (Pt) and platinum–nickel (Pt–Ni) electrocatalysts were prepared on activated graphite electrodes by an electrochemical deposition process. The electrocatalysts were analyzed by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). The electrocatalytic activity of the prepared electrocatalysts, their stability, and the effect of temperature toward ethanol and 2-propanol oxidation were evaluated by cyclic voltammetry (CV), chronoamperometry and electrochemical impedance spectroscopy (EIS). The results showed that the Pt–Ni/C exhibited higher catalytic activity, better stability and better tolerance to poisoning by ethanol and 2-propanol oxidation intermediate species compared to Pt/C, which was interpreted as synergistic and electronic effects between Pt and Ni. A study of the temperature dependence of ethanol and 2-propanol oxidation in the temperature range of 298–318 K, shows that the apparent activation energy for ethanol and 2-propanol oxidation on Pt–Ni/C was lower than on Pt/C. The results also revealed that the electro-oxidation of ethanol and 2-propanol on Pt/C were improved by raising the temperature and Ni modification.

DOI: 10.1039/D0RA07331H