Active control of the nonlinear bending behavior of magnetorheological elastomer sandwich beam with magnetic field

The purpose of this work is to analyze the nonlinear mechanical behavior of sandwich structures with a magnetorheological elastomer (MRE) core subjected to a permanent magnetic field. A detailed study is first carried out to characterize the mechanical behavior of these structures. The tests were carried out in three-point bending on beams of these complex materials for several distances between supports. An experimental study, of the mechanical behavior response realized using a Zwick 2.5 kN machine, allows to measure displacements as a function of force. The results deduced from the numerical simulation by the Abaqus software are compared with those obtained from the theoretical analysis. This study allows to show that these structures exhibit a non-linear behavior even at small deformations due to the rheological parameters which are more sensitive by the application of a magnetic field

Peptídeo do hidrolisado protéico de RuBisCO e sua aplicação na preservação de carne bovina

The objective of this work was to purify the small (705 Da) and hydrophilic antimicrobial Arg-Asp-Arg-Phe-Leu peptide from RuBisCO protein hydrolysate and to evaluate its effect on the microbiological and oxidative stability of beef mince during refrigeration. RuBisCO was obtained from alfafa green juice. The peptide extract was fractionated using RP-HPLC, and the active fractions were analyzed by liquid chromatography, electrospray ionization, and tandem mass spectrometry (LC-ESI-MS). Beef mince was analyzed in the following treatments: negative control, meat with two different BHT concentrations of 0.1 and 0.5% (w/w), and meat with two different Arg-Asp-Arg-Phe-Leu peptide concentrations of 0.1 and 0.5% (w/w). Lipid oxidation using the thio-barbituric acid-reactive substance (TBARS) values were significantly affected by the storage period and the concentration of bioactive peptide. Arg-Asp-Arg-Phe-Leu, a small antibacterial peptide from RuBisCO, can be isolated and purified by HPLC from alfafa green juice with retention time between 10 and 50 min, which corresponds to antimicrobial peptides. RuBisCO peptide Arg-Asp-Arg-Phe-Leu 0.5% increases oxidative stability of beef mince during refrigeration. RuBisCO peptide Arg-Asp-Arg-Phe-Leu inhibit microbial growth under refrigeration for 11 days.O objetivo deste trabalho foi purificar peptídeo antimicrobiano pequeno (705 Da) e hidrofílico Arg-Asp-Arg-Phe-Leu a partir do hidrolisado proteico RuBisCO e avaliar seu efeito na estabilidade microbiológica e oxidativa de carne bovina moída durante refrigeração. RuBisCO foi obtida a partir do suco verde de alfafa. O extrato peptídico foi fracionado utilizando RP-HPLC, e as frações ativas foram analisadas por cromatografia líquida, ionização por eletrospray e espectrometria de massa em tandem (LC-ESI-MS). A carne bovina moída foi analisada nos seguintes tratamentos: controle negativo, carne com duas concentrações diferentes de BHT de 0,1 e 0,5% (p/p) e duas concentrações de peptideo Arg-Asp-Arg-Phe-Leu de 0,1 e 0,5% (p/p). Os valores de oxidação lipídica utilizando a substância reativa ao ácido tiobarbitúrico (TBARS) foram significativamente afetados pelo período de armazenamento e pela concentração do peptídeo bioativo. Arg-Asp-Arg-Phe-Leu, um pequeno peptídeo de RuBisCO, pode ser isolado e purificado por HPLC de suco verde de alfafa com tempos de retenção de 10 e 50 min, o que corresponde ao peptídeo antimicrobiano. O peptídeo Arg-Asp-Arg-Phe-Leu 0,5% aumenta a estabilidade de oxidação da carne moída durante a refrigeração. O peptídeo Arg-Asp-Arg-Phe-Leu de RuBisCO inibe o crescimento microbiano sob refrigeração durante 11 dias

Peptide from RuBisCO protein hydrolysate and its application in beef meat preservation

Abstract The objective of this work was to purify the small (705 Da) and hydrophilic antimicrobial Arg-Asp-Arg-Phe-Leu peptide from RuBisCO protein hydrolysate and to evaluate its effect on the microbiological and oxidative stability of beef mince during refrigeration. RuBisCO was obtained from alfafa green juice. The peptide extract was fractionated using RP-HPLC, and the active fractions were analyzed by liquid chromatography, electrospray ionization, and tandem mass spectrometry (LC-ESI-MS). Beef mince was analyzed in the following treatments: negative control, meat with two different BHT concentrations of 0.1 and 0.5% (w/w), and meat with two different Arg-Asp-Arg-Phe-Leu peptide concentrations of 0.1 and 0.5% (w/w). Lipid oxidation using the thio-barbituric acid-reactive substance (TBARS) values were significantly affected by the storage period and the concentration of bioactive peptide. Arg-Asp-Arg-Phe-Leu, a small antibacterial peptide from RuBisCO, can be isolated and purified by HPLC from alfafa green juice with retention time between 10 and 50 min, which corresponds to antimicrobial peptides. RuBisCO peptide Arg-Asp-Arg-Phe-Leu 0.5% increases oxidative stability of beef mince during refrigeration. RuBisCO peptide Arg-Asp-Arg-Phe-Leu inhibit microbial growth under refrigeration for 11 days

Elaboration et caractérisation d’un matériau composite avec différents renforts

93 p. : ill. ; 30 cmCe travail consiste en une caractérisation expérimentales et numérique d’un matériau composite de base verre/époxy renforcé par des particules métalliques récupérés. Le composite est élaboré par le procédé moulage au contact cette caractérisation a pris en compte l’influence de l’ajout de ces particules sur les caractéristiques mécaniques du matériau de base , notamment la rigidité Après les analyses physico chimiques et l’étude de comportement mécanique de chaque constituant, les premiers résultats montrent l’effet des particules sur la résine vierge, et de même pour le composite. L’influence des paramètres géométriques et de teneur de ces particules sur le comportement mécanique des composites en traction, flexion et compression sont étudiées.L’approche numérique basé sur l’idée de placer une feuille mince de métal à l’interface donné des résultats intéressant

Physicochemical and biological properties of eel by-products protein hydrolysates: Potential application to meat product preservation

European eel by-products have been hydrolysed in order to produce novel bioactive peptides with antibacterial and antioxidant activity. Protein hydrolysates from Anguilla by-products obtained by treatment with Savinase® (PHAB-s) have high protein content than that produced with Protamex® (PHAB-p). Furthemore, both protein hydrolysates had a high percentage of essential amino acids. In addition, results indicated that PHAB-s and PHAB-p exhibited different degrees of antioxidant activities, evaluated by several antioxidant assays. Thus, PHAB-s displayed high antioxidant activity, in terms of DPPH-radical scavenging effect (IC50 = 5.2 mg/ml), β-carotene bleaching inhibitory effect (CI50 = 4.4 mg/ml) and metal chelating activity. At 10 mg/ml, PHAB-p showed the highest reducing power. Antibacterial activities of PHAB-s and PHAB-p were also evaluated. PHAB-s showed the most important inhibitory effects against seven bacterial species. The application of PHAB-s and PHAB-p on minced meat as preservative reduced the lipid oxidation and inhibited the microbial growth during chilled storage for 11 days.This work was funded by the Ministry of Higher Education and Scientific Research, Tunisia and the Spanish Ministry of Economy, Industry and Competitiveness under project AGL2014-52825-R.Peer reviewe

Biochemical and antioxidant properties of peptidic fraction of carotenoproteins generated from shrimp by-products by enzymatic hydrolysis

The composition, functional properties and in vitro antioxidative activity of the peptidic fraction of carotenoproteins from shrimp (Parapenaeus longirostris) by-products generated by enzymatic treatment with Alcalase® was evaluated. The peptidic fraction of carotenoproteins (PFCP) contained 80.8 ± 0.21% protein, 2.74 ± 0.3% lipid, 14.4 ± 0.14% ash, 1.13 ± 0.08% chitin and 1.08 ± 0.02 μg total carotenoid/g of sample. The amino acid profile of PFCP showed a high percentage of essential amino acids, such as arginine, lysine, histidine and leucine. Therefore, PFCP had a high nutritional value and could be used as a supplement to poorly balanced dietary proteins. PFCP showed an excellent solubility and possessed interfacial properties, which were governed by their concentrations. The antioxidant activities of PFCP at different concentrations were evaluated using various in vitro antioxidant assays, including the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical method, reducing power, chelating effects assay and β-carotene bleaching. The antioxidant activity of PFCP, based on their protection of supercoiled DNA strand from scission by peroxyl and hydroxyl radicals into the nicked circular form was also investigated. Results from this study suggest that the peptidic fraction of carotenoproteins is a good source of natural antioxidants and peptides with interesting functionalities.This work was funded by the Ministry of Higher Education and Scientific Research, Tunisia, and also by the Spanish Ministry of Foreign Affairs (ref. AP/038291/11).Peer Reviewe

Procédé d’extraction et de production d’hydrolysats de protéines de pois chiche enrichis en peptides antioxydants. Purification et identification de deux biopeptides

publication date: 2017-05-08; filing date: 201