Accueil
JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) . Vol. CXIII, N° 2Mention de date : 02/2018Paru le : 12/02/2018 |
Dépouillements
Ajouter le résultat dans votre panierInvestigation of moderately halophilic bacteria causing deterioration of the salted sheep and goat skins and their extermination via electric current applications / Pinar Caglayan in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXIII, N° 2 (02/2018)
[article]
Titre : Investigation of moderately halophilic bacteria causing deterioration of the salted sheep and goat skins and their extermination via electric current applications Type de document : texte imprimé Auteurs : Pinar Caglayan, Auteur ; Meral Birbir, Auteur ; Cristina Sánchez-Porro ; Antonio Ventosa ; Yasar Birbir Année de publication : 2018 Article en page(s) : p. 41-52 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Bactéries
Courants alternatifs
Courants électriques
Cuirs et peaux -- Analyse
Cuirs et peaux -- Conservation
Cuirs et peaux de chèvres
Cuirs et peaux de moutonsIndex. décimale : 675 Technologie du cuir et de la fourrure Résumé : Determination of moderately halophilic bacterial counts on the salted skins and examination of utilization of amino acid and carbon sources by skin isolates offer important information about biodegradation of salted skins. Hence, total counts of moderately halophilic bacteria, total counts of proteolytic and lipolytic moderately halophilic bacteria found on the salted sheep and goat skins belonging to different countries were examined in this study. One hundred-thirty seven moderately halophilic bacterial species closely related to species of genera Alkalibacillus, Bacillus, Chromohalobacter, Gracilibacillus, Halomonas, Idiomarina, Marinococcus, Oceanobacillus, Planococcus, Salimicrobium, Salinicoccus, Staphylococcus and Salinivibrio were used to detect utilization of different amino acids and carbon sources which are related to biodegradation of skins. The values of pH, moisture contents, ash contents and salt saturations of these skins were also investigated to understand the correlation between these parameters and moderately halophilic bacterial activities. All salted skin samples contained moderately halophilic bacteria, proteolytic and lipolytic moderately halophilic bacteria in high numbers. Each of 137 test isolates, obtained from the salted sheep and goat skins, used different amino acids found in the skin structure. While 100% of both sheep and goat skin isolates utilized L-arginine, 86%, 66%, 85%, 64% and 66% of the isolates respectively utilized L-glycine, L-alanine, L-tyrosine, L-proline and L-hydroxyproline amino acids. Ninety-three percent of the isolates used different carbon sources such as dulcitol (13%), D-sorbitol (29%), L-rhamnose (19%), ribose (52%), salicin (40%), myo-inositol (27%), xylitol (21%), benzoate (18%), propionate (34%), D-melezitose (31%), butanol (20%), propanol (23%), methanol (23%), formate (23%) and tartrate (12%). While pH values, moisture contents, ash contents and salt saturations of the sheep skins ranged from 6.53 to 8.01, 32 to 68%, 12 to 30% and 58 to 100%, respectively, the pH values, moisture contents, ash contents and salt saturations of the goat skins were between 6.65-8.06, 34-70%, 11-32% and 64-100%, respectively. The values of all skin samples were found to be suitable for the growth and catabolic activities of these bacteria. To prevent the growth and activities of moderately halophilic isolates causing skin deterioration, the annihilation effects of 0.5, 1.0, 1.5 and 2.0 A direct and alternating electric current treatments on the mixed culture of moderately halophilic isolates (Chromohalobacter israelensis, Chromohalobacter canadensis, Halomonas halodenitrificans, Staphylococcus nepalensis and Halomonas halmophila) were also separately investigated in the present study. Both 0.5, 1.0, 1.5, 2.0 A direct and alternating electric current applications used in this study completely annihilated the mixed culture of moderately halophilic spoilage microorganisms. As a conclusion, we suggest using lowlevel direct or alternating electric current treatment to eradicate harmful moderately halophilic bacteria in salt which will be used in brine curing of hides and skins in the leather industry. Note de contenu : - EXPERIMENTAL : Skin Samples - Determination of total of moderately halophilic bacteria on the skin samples - Determination of total counts of proteolytic and lipolytic moderately halophilic bacteria on the skins - Utilization of different amino acids and different carbon sources - Determination of pH values of the salted skins - Determination of moisture content, ash content and salt saturation of the salted skins - Application of alternating and direct electric currents on the mixed culture
- RESULTS AND DISCUSSION : Moderately halophilic bacteria, proteolytic and lipolytic bacteria on salted sheep and goat skin samples - Determination of pH value, moisture content, ash content and salt saturation of the salted skins - Utilization of different amino acids and different carbon sources - Application of alternating and direct electric currents on the mixed culture of moderately halophilic spoilage bacteriaEn ligne : https://drive.google.com/file/d/13FYlhwuWlVz9ABkOdZFqz5LbN0xD_nh_/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=29950
in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXIII, N° 2 (02/2018) . - p. 41-52[article]Réservation
Réserver ce document
Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité 19539 - Périodique Bibliothèque principale Documentaires Disponible Ultrasound assisted vegetable tannin extraction from myrobalan nuts for leather application / Venkatasubramanian Sivakumar in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXIII, N° 2 (02/2018)
[article]
Titre : Ultrasound assisted vegetable tannin extraction from myrobalan nuts for leather application Type de document : texte imprimé Auteurs : Venkatasubramanian Sivakumar, Auteur ; A. Princess, Auteur ; C. Veena ; R. Lakshmi Devi Année de publication : 2018 Article en page(s) : p. 53-58 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Eau
Essais (technologie)
Extraction par solvant
Extraction par ultrasons
Myrobalan et constituants
Tanins végétaux
Tannage végétal -- AnalyseIndex. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : Ultrasound (US) assisted preparation of tannins from Terminalia Chebula nuts (myrobalan) through solid-liquid extraction process using water as solvent even dispensing with conventional heating/stirring is presented in this paper. The results indicate there is a significant enhancement in myrobalan extraction due to the influence of US, in extract %yield and tannin contents respectively as compared to different control processes (static/stirring). Whereas, ultrasound probe at 120 W in 50°C water bath gave the best overall %yield and tanning content. Some of the important scale-up parameters could be a significant savings of 427,184 and 188 kg per ton of raw material usage as extrapolated values based on Lab-scale results in terms of % yield, tannin content and tanning agent offer respectively due to the use of US as compared to control process. The process involves : i). Clean technology with physical activation (US) in aqueous medium at ambient condition - no additional chemicals ii). Green and Eco-benign process with natural materials - useful in all extract applications, iii. Tannins extract as generic product for better functional properties, iv). Better diffusion of plant extract through skin matrix in tanning process for leather making, v). Sustainable solution and ecoconservation through better yields Note de contenu : - EXPERIMENTAL : Experimental Set up - Experimental Procedure - Tanning Trials - Analytical methods - Quantitative analysis of tannin content
- RESULTS AND DISCUSSIONS : Myrobalan extraction in ultrasonic tank - Effect of extraction in US probe - Effect of US power, temperature and stirring in extration - Enhancement factors for myrobalan extraction with ultrasound - Effect of distance of material from US probe tip - Mechanism tor the ultrasound assisted extraction - Two-stage extraction - Efficacy of extract in tanning process - Experimental results and process scale-up considerationsEn ligne : https://drive.google.com/file/d/1Nfgs9Mp-HnCkG6Q4zlf4t-oXsI-oBK3b/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=29951
in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXIII, N° 2 (02/2018) . - p. 53-58[article]Réservation
Réserver ce document
Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité 19539 - Périodique Bibliothèque principale Documentaires Disponible Approach towards safe and efficient enzymatic unhairing of bovine hides / Mei Chen in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXIII, N° 2 (02/2018)
[article]
Titre : Approach towards safe and efficient enzymatic unhairing of bovine hides Type de document : texte imprimé Auteurs : Mei Chen, Auteur ; Mingfang Jiang, Auteur ; Min Chen ; H. Cheng Année de publication : 2018 Article en page(s) : p. 59-64 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Caséine Les caséines sont des protéines qui constituent la majeure partie des composants azotés du lait. La première phase de la fabrication du fromage est leur précipitation par adjonction d'un acide ou de présure. Le mot caséine est issu du latin caseus, "fromage".
- Caractéristiques : La quantité des caséines d'un lait varie selon les espèces animales : 82 % (des protéines) pour le lait de vache et 40 % pour le lait humain.
L'hydrolyse d’une caséine fait ressortir des teneurs élevées en acide glutamique, proline, leucine, lysine, sérine et thréonine.
- Caséines bovines : Il y a plusieurs types de caséines dans le lait de vache. Les plus présentes sont les caséines αS1 (40 %), β (35 %), κ (12 %), αS2 (10 %) et γ (3 à 7 %).
La caséine du lait de vache précipite facilement en caillots blancs, soit par abaissement du pH au voisinage de son point isoélectrique (pH 4,6), soit par action enzymatique (présure). La caséine du lait humain ne précipite pas par simple acidification. Cependant, la précipitation à un pH de 6 est immédiate en présence du suc gastrique du nourrisson à cause de la présure qu'il contient (la chymosine pour être précis).
- Caséines humaines : Les caséines représentent 40 % des protéines du lait humain contre 82 % dans le lait de vache. Elles forment également des micelles plus petites qui expliquent en plus de la haute teneur en protéine solubles la coagulation plus fine du lait maternel dans l’estomac du nourrisson. (Wikipedia)
Cuirs et peaux de bovins
Epilage enzymatique
Hydrolyse enzymatique
Ions métalliquesIndex. décimale : 675 Technologie du cuir et de la fourrure Résumé : Unhairing is an essential step in leather manufacturing. The traditional hair-burning technology brings huge sulfide pollution and large COD, BOD in the effluent. Hair-saving enzymatic unhairing is a popular method for displacing sulfide unhairing. However, some of the problems associated with enzymatic unhairing are need for greater control over process parameters and possibility of grain damage to the pelt. To overcome these challenges, an attempt has been made to utilize bivalent metal ions for safe and efficient enzymatic unhairing on bovine hides. The effect of metal ions such as Ca(II), Mg(II), Mn(II), and Zn(II) ions on the activity of AS1.398 protease for hydrolyzing collagen and casein was investigated. The findings were corroborated with the bovine hide unhairing and the resultant leathers were of appreciable quality. The outcomes of this study could add to the knowledge of enzymatic unhairing leading to cleaner leather manufacturing in a safe and efficient way. Note de contenu : - MATERIALS AND METHODS : Enzymatic activity assays - Effect of metal ions to collagen hydrolytic activity - The procedure of enzymatic unhairing with metal ions - Determination of the total protein content - Determination of the hydroxyproline content - Physical properties testing
- RESULTS AND DISCUSSION : Effect of metal ions to AS1.398 hydrolyzing of collagen fibers - Effect of metal ions to AS1.398 hydrolyzing of casein - Application on enzymatic unhairing processEn ligne : https://drive.google.com/file/d/1Q0ApdHCgWu1jtinc_Um-xzBwSplvAn9-/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=29953
in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXIII, N° 2 (02/2018) . - p. 59-64[article]Réservation
Réserver ce document
Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité 19539 - Périodique Bibliothèque principale Documentaires Disponible A simple test to determine the propensity of a sample of leather to the formation of chromium / Joaquim Font in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXIII, N° 2 (02/2018)
[article]
Titre : A simple test to determine the propensity of a sample of leather to the formation of chromium Type de document : texte imprimé Auteurs : Joaquim Font, Auteur ; Marta Bacardit, Auteur ; Niria Pascual ; Rosa M. Cuadros ; Francina Izquierdo Année de publication : 2018 Article en page(s) : p. 65-71 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Analyse quantitative (chimie)
Colorimétrie
Cuir -- Teneur en chrome hexavalent
Cuirs et peaux -- Analyse
Décoloration
Extraction par solvant
PyrolyseLa pyrolyse est la décomposition ou thermolyse d'un composé organique par la chaleur pour obtenir d'autres produits (gaz et matière) qu'il ne contenait pas. L'opération est réalisée en l'absence d'oxygène ou en atmosphère pauvre en oxygène pour éviter l'oxydation et la combustion (L’opération ne produit donc pas de flamme). Il s'agit du premier stade de transformation thermique après la déshydratation.
Elle permet généralement d'obtenir un solide carboné, une huile et un gaz. Elle débute à un niveau de température relativement bas (à partir de 200 °C) et se poursuit jusqu'à 1 000 °C environ. Selon la température, la proportion des trois composés résultants est différente.Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Since the EU Commission Regulation of chromium(VI) in leather articles, there is a huge demand of analyses and controls in the leather sector for this parameter.
However, for many tanners and leather dealers, the necessary cost to have a laboratory capable to carry out the analyses according to an ISO method is not affordable.
An easy test has been developed to carry out a screening of a leather sample in order to check out its compliance with the Cr(VI) restriction. This test is able to distinguish leathers that contain chromium(VI) or show signs of tendency to develop it, from leathers that even after thermal ageing exposure remain free of it.
The test is based on the scientist principle of the ISO 17075-1 method. Some operations of this Standard have been adapted with the aim of saving costs and simplifying and shortening the workload of the test. The essential criterion of this adaptation has been that the developed test does not lead to false negatives.
The only required devices are a laboratory oven, a balance of 0.01g of resolution, and a shaker. Neither a spectrophotometer nor a colorimeter is necessary.
The method has four main steps. The first one is an ageing process at 80°C during 24 hours. After cooling down for 30 minutes, the sample is extracted for one hour, using an overhead rotatory shaker or a magnetic stirrer. The third step is the discoloration of the extract, to remove the dyes of the colored solution so as to eliminate interferences. Finally, the extract is assessed by visual colorimetry. The workload per sample is about 40 minutes.
So far, more than 300 samples of leather have been tested. The kit performed very well and only gave 5% of false positives. The kit did not commit any false negative.Note de contenu : - MATERIALS AND METHODS : Samples - Reagents and instruments for the LeatherKit_Cr6 method - Instruments for the ISO 17075-2 reference method - Operating procedure for LeatherKit_Cr6 method - Measurement
- RESULTS AND DISCUSSION : Ageing - Cooling down time - Degasification of samples and extration solution - Extraction procedure - Color removal - DeterminationEn ligne : https://drive.google.com/file/d/1-Pc0JEd9a6YcAPhK0_-PJAntrsYBnDj0/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=29955
in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXIII, N° 2 (02/2018) . - p. 65-71[article]Réservation
Réserver ce document
Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité 19539 - Périodique Bibliothèque principale Documentaires Disponible
Exemplaires (1)
Code-barres | Cote | Support | Localisation | Section | Disponibilité |
---|---|---|---|---|---|
19539 | - | Périodique | Bibliothèque principale | Documentaires | Disponible |