![](./images/home.jpg)
![](./images/bar_spacer.gif)
Catégories
![](./images/expand_all.gif)
![](./images/collapse_all.gif)
![](./images/orderby_az.gif)
Etendre la recherche sur niveau(x) vers le bas
Rapid fiber opening process for skins : an approach for fail-safe chemical-free process / Jayanthi Durga in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CX, N° 1 (01/2015)
![]()
[article]
Titre : Rapid fiber opening process for skins : an approach for fail-safe chemical-free process Type de document : texte imprimé Auteurs : Jayanthi Durga, Auteur ; Ammasi Ranjithkumar, Auteur ; Ramakrishnan Ramesh, Auteur ; Chellan Rose, Auteur ; Chellappa Muralidharan, Auteur Année de publication : 2015 Article en page(s) : p. 7-12 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Carbohydrases
Cuirs et peaux -- Analyse
Cuirs et peaux de chèvres
Epilage enzymatique
Travail de rivière (cuir)
Wet-blue (tannage)Peau tannée au chrome (le chrome donne une couleur bleue)Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Conventional beamhouse operations adopted by the global tanning industry are coming under the close scrutiny of the environmentalists on account of the possible adverse effect on human health and environment. Lime, which is used to the tune of about 10% on the weight of the raw hides and skins, in re-liming stage contribute to generation of large quantities of sludge, the disposal of which is a serious concern. Also the process duration to achieve the required fiber opening in the re-liming process is very long, ranging from 24-72 hrs for different substrates and end products. Enzyme based beamhouse processes are being advocated to overcome the problems associated with the conventional processes. However, enzyme based methods need greater control over process parameters to achieve satisfactory results in leather processing and avoid damage to the pelt. To overcome the problems associated with the conventional re-liming process, an attempt has been made in the present investigation to utilize cocktail of carbohydrases for fiber opening of hides and skins. Fiber opening at optimized concentration of the above enzyme has been studied for its efficiency on goatskins. A process using optimum quantity of enzyme led to fiber opening in 30 minutes. The efficacy of enzyme on rapid fiber opening of dehaired skin was studied at different experimental conditions of pH, time and enzyme concentration. The performance of the enzyme in the given experimental conditions was assessed by quantifying the removal of carbohydrate and proteoglycan and examining the fiber opening by scanning electron microscopic studies. Effect of enzyme on the final quality of the leather was evaluated by changes in chemical characteristics, physical properties and visual examination. Note de contenu : - EXPERIMENTAL : Optimization of enzyme concentration - pH optimization - Time course study - Carbohydrate assay - Estimation of proteoglycan - Scanning electron microscopic analysis - Physical testing and visual assessment
- RESULTS AND DISCUSSION : Effect of enzyme concentration of fiber opening - Effect of pH on fiber opening - Effect of time on fiber opening - Chromium content of wet blue leather - Scanning electron micrography - Physical and organoleptic propertiesEn ligne : https://drive.google.com/file/d/1exmz-jTGm0C0NTh0WpzBYlQtS-Ni_g4y/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=22791
in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CX, N° 1 (01/2015) . - p. 7-12[article]Réservation
Réserver ce document
Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité 16774 - Périodique Bibliothèque principale Documentaires Disponible Recovery of industrially useful hair and fat from enzymatic unhairing of goatskins during leather processing / Joseph Ondari Nyakundi in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXVII, N° 6 (06/2022)
![]()
[article]
Titre : Recovery of industrially useful hair and fat from enzymatic unhairing of goatskins during leather processing Type de document : texte imprimé Auteurs : Joseph Ondari Nyakundi, Auteur ; Jackson Nyarongi Ombui, Auteur ; Wycliffe Chisutia Wanyonyi, Auteur ; Francis Jakim Mulaa, Auteur Année de publication : 2022 Article en page(s) : p. 241-250 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Caractérisation
Cuirs et peaux de chèvres
Epilage enzymatique
Essais (technologie)
Evaluation
Huiles et graisses -- Recyclage
Huiles et graisses animales
Poils -- Recyclage
Qualité -- Contrôle
Récupération (Déchets, etc.)Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Leather processing not only serves social needs by putting into use the meat industry’s by-products (hides and skins) but also makes a significant contribution to global economic growth through trade and job creation. In the wake of globalization, however, leather manufacturers are facing new challenges in meeting environmental imperatives and improving the utilization of wastes generated during leather processing. This study describes the recovery of hair and fat
from fleshings obtained after enzymatic unhairing of goatskins using a protease from an isolate of Bacillus cereus Strain 1-p. The recovered hair and fats were further characterized to facilitate recommendations for different industrial applications. The following hair properties were visually examined and evaluated by hand ; straight length, density and uniformity, hair strength and overall quality. The fats were analyzed by characterizing the fatty acid composition using the Gas Chromatography-Mass Spectrometry (GC-MS analysis). The recovered hair was intact and rated to be of average to good quality. The fat characterization indicated that methyl 9Z-octadecenoate (9Z-heptadecenoic acid; oleic acid) was the most abundant fatty acid with an abundance of 31.65%. The sulfide-free fats and intact hair, therefore, were recommended for use in various industrial applications such as manufacturing of poultry feedstuff, organic fertilizers, biodiesel and biofuels, fatliquoring agents, soaps and cosmetics after further purification where necessary. The hair and fats recovered from this study are particularly advantageous over those recovered from sulfide unhairing systems as they are free from any sulfides or lime contamination thus easier to purify and use. The study concluded that the use of the enzyme extract from Bacillus cereus Strain 1-p to unhair goatskins facilitated the recovery of valuable hair and fats that can be used for other industrial applications.Note de contenu : - MATERIALS AND METHODS : Materials - Methods (Enzyme preparation - Unhairing of goatskins) - Characterization of the recovered products
- RESULTS AND DISCUSSION : Recovered hair analysis - Recovered fat analysis
- Table 1 : Assesment of recovered hair quality
- Table 2 : Fatty acids test resultsDOI : https://doi.org/10.34314/jalca.v117i6.4965 En ligne : https://drive.google.com/file/d/13xpAHCyMlTJBIwqMWXKZCUw9d_FUgOJp/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=37799
in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXVII, N° 6 (06/2022) . - p. 241-250[article]Réservation
Réserver ce document
Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité 23490 - Périodique Bibliothèque principale Documentaires Disponible Resource utilization of bovine hair recycling from enzymatic unhairing during leather manufacturing : Alkali-protease synergistic preparation of keratin and its in vitro antioxidant activity / Ting Liu in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXVIII, N° 9 (09/2023)
![]()
[article]
Titre : Resource utilization of bovine hair recycling from enzymatic unhairing during leather manufacturing : Alkali-protease synergistic preparation of keratin and its in vitro antioxidant activity Type de document : texte imprimé Auteurs : Ting Liu, Auteur ; Chunxiao Zhang, Auteur ; Xu Zhang, Auteur ; Biyu Peng, Auteur ; Mengchun Gao, Auteur Année de publication : 2023 Article en page(s) : p. 367-378 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Bases (chimie)
Cuirs et peaux de bovins
Epilage enzymatique
Extraction (chimie)
Hydrolyse enzymatique
kératineLa kératine est une protéine, synthétisée et utilisée par de nombreux êtres vivants comme élément de structure, et également l'exemple-type de protéine fibreuse.
La kératine est insoluble, et peut être retrouvée sur l'épiderme de certains animaux, notamment les mammifères, ce qui leur garantit une peau imperméable. Parfois, lors d'une friction trop importante, la kératine se développe à la surface de la peau formant une callosité. Les cellules qui produisent la kératine meurent et sont remplacées continuellement. Les morceaux de kératine qui restent emprisonnés dans les cheveux sont couramment appelés des pellicules.
La molécule de kératine est hélicoïdale et fibreuse, elle s'enroule autour d'autres molécules de kératine pour former des filaments intermédiaires. Ces protéines contiennent un haut taux d'acides aminés à base de soufre, principalement la cystéine, qui forment un pont disulfure entre les molécules, conférant sa rigidité à l'ensemble. La chevelure humaine est constituée à 14 % de cystéine.
Il y a deux principales formes de kératines : l'alpha-kératine, ou α-keratin, présente chez les mammifères notamment, dont l'humain, et la bêta-kératine, ou β-keratin, que l'on retrouve chez les reptiles et les oiseaux. Ces deux types de kératines ne présentent clairement pas d'homologie de séquence.
Chez l'être humain, la kératine est fabriquée par les kératinocytes, cellules se trouvant dans la couche profonde de l'épiderme. Les kératinocytes absorbent la mélanine (pigment fabriqué par les mélanocytes), se colorent et ainsi cette pigmentation de l'épiderme permet de protéger les kératinocytes des rayons ultraviolets du Soleil.
Peptidases
Poils -- RecyclageIndex. décimale : 675 Technologie du cuir et de la fourrure Résumé : With the development of enzymatic unhairing technology in the leather industry, enhancing the recycling of bovine hair is a new issue emerging in leather-making. In this work, the effects of alkali concentration, time, and temperature in the pretreatment, as well as enzyme dosage, time, temperature, and pH in the following treatment on the dissolution performance and keratin yield of bovine hair were investigated. Hence, the extraction process of keratin from bovine hair by the alkali-enzyme method was optimized. The results sho that the optimal conditions for the keratin extraction are as follows: for the pretreatment with alkali, the alkali concentration is 0.4 M, the pretreatment time is 1.0 h, the pretreatment temperature is 65°C, and for the following enzymatic treatment, the enzyme dosage is 3324 U/g bovine hair, the action time is 4.0 h, action temperature is 45°C, and the pH is controlled between 8.5-11.5. Compared with the alkali method, the alkali-enzyme method increases the keratin yield from 24.4% to 58.1%, and the alkali dosage is reduced by 50%. The prepared keratin had high in vitro antioxidant activity, which provided a new idea for the resource utilization of bovine hair waste. Note de contenu : - MATERIALS AND METHODS : Pretreating the bovine hair with differing concentration of NaOH before enzymatic hydrolysis - Effect of alkaline pretreating time on enzymatic hydrolysis of bovine hair - Effect of alkaline pretreating temperature on enzymatic hydrolysis of bovine hair - Effect of protease dosage on enzymatic hydrolysis of bovine hair - effect of pH on enzymatic hydrolysis of bovine hair - Effect of time on enzymatic hydrolysis of bovine hair - Effect of temperature on enzymatic hydrolysis of bovine hair - orthogonoal experiments for hydrolysis of bovine hair by alkali-enzyme synergy - Determination of bovine hair solubility and keratin extraction rate - Determination of molecular weight - Analysis of amino acid composition of bovine hair keratin - Determination of DPPH scavenging activity - Determination of ABTS scavenging activity
- RESULTS AND DISCUSSION : Optimization of alkali pretreatment parameters - Optimization of enzymatic hydrolysis parameters - Optimization of orthogonal experiment - Analysis and evaluation of the keratin extracted from bovine hair - Amino acid composition of bovine hair keratin - DPPH free radical scavenging ability - ABTS free radical scavenging ability
- Table 1 : Horizontal table of orthogonal experimental factors
- Table 2 : Molecular weight distribution of keratin with differing NaOH concentration
- Table 3 : Results of orthogonal experiment of keratin preparation obtained from bovine hair by alkaly-enzyme method
- Table 4 : Comparison of keratin extraction of alkali-enzyme and alkaline hydrolysis method
- Table 5 : Molecular weight distribution of keratin
- Table 6 : Analysis of amino acid compositio of bovine hair and keratin (mg/100 mg
- Table 7 : DPPH free radical scavenging abilities of keratin under different concentrations
- Table 8 : ABTS free radical scavenging abilities of keratin under different concentrationsDOI : https://doi.org/10.34314/jalca.v118i9.8190 En ligne : https://drive.google.com/file/d/1_PY7W_CJUD1RdJJrotAmABi-_4Cq_QnI/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=39827
in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXVIII, N° 9 (09/2023) . - p. 367-378[article]Réservation
Réserver ce document
Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité 24196 - Périodique Bibliothèque principale Documentaires Disponible Screening of additives to reduce grain damage risk on unhairing by proteinase K / Mei Chen in JOURNAL OF LEATHER SCIENCE AND ENGINEERING, Vol. 2 (Année 2020)
![]()
[article]
Titre : Screening of additives to reduce grain damage risk on unhairing by proteinase K Type de document : texte imprimé Auteurs : Mei Chen, Auteur ; Mingfang Jiang, Auteur ; He Li, Auteur ; Cheng Haiming, Auteur Année de publication : 2020 Article en page(s) : 9 p. Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Additifs
Criblage
Cuirs et peaux de bovins
Epilage enzymatique
Hydrolyse enzymatique
Inhibiteurs (chimie)
Ions métalliquesIndex. décimale : 675 Technologie du cuir et de la fourrure Résumé : Enzymatic unhairing is a cleaner strategy for leather-making. It is a potential alternative to the traditional hair-burning process. However, several shortcomings, such as uncontrolled enzymatic reaction, and risk of grain looseness and damage have restricted the broad application of enzymatic unhairing. In this work, metal ions and organic additives were screened for lessening the hydrolytic activity of proteinase K to collagen fiber. Then, the selected additives were applied to the enzymatic unhairing process for bovine hide. The results showed that a suitable concentration of metal ions (Cu (II), Fe (III) and Al (III)) and organic additives (salicylate, laurate, adipate, gallate and epicatechin (ECG)) could diminish approximately 35% of the hydrolytic activity of proteinase K to collagen fibers. Then, the additives were applied for the bovine hide enzymatic unhairing process. Hydroxyproline determination in the unhairing float shows that applying additives could reduce collagen hydrolysis. The morphology results showed that the grain damage could be significantly reduced with the addition of the screened additives in the proteinase K enzymatic unhairing system, whereas the addition of ECG and gallate significantly slowed down the unhairing speed. This outcome provides new potential to reduce the risk of grain damage in enzymatic unhairing process. Note de contenu : - MATERIALS AND METHODS : Materials - Enzymatic activity assays - Effect of additives on hydrolytic activities of proteinase K - Determination of total protein (TP) content - Determination of hydroxyproline (Hyp) content - Scanning electron microscopy (SEM)
- RESULTS AND DISCUSSION : Screening of additives - Enzymatic unharing by proteinase K with additives
- Table 1 : The effect of the additives on the hydrolytic activity of proteinase K
- Table 2 : The results of enzymatic unhairing by proteinase K (150 U/g hide) with additives at 35 °C, pH 8.0DOI : https://doi.org/10.1186/s42825-020-00032-1 En ligne : https://link.springer.com/content/pdf/10.1186/s42825-020-00032-1.pdf Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=37451
in JOURNAL OF LEATHER SCIENCE AND ENGINEERING > Vol. 2 (Année 2020) . - 9 p.[article]Studies on the use of bi-functional enzyme for leather making / Gladstone Christopher Jayakumar in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXI, N° 12 (12/2016)
![]()
[article]
Titre : Studies on the use of bi-functional enzyme for leather making Type de document : texte imprimé Auteurs : Gladstone Christopher Jayakumar, Auteur ; Murali Sathish, Auteur ; Rathinam Aravindhan, Auteur ; Jonnalagadda Raghava Rao, Auteur Année de publication : 2016 Article en page(s) : p. 455-460 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Amylase L'amylase (EC 3.2.1.1) est une enzyme digestive classée comme saccharidase (enzyme qui brise les polysaccharides). C'est surtout un constituant du suc pancréatique et de la salive, requis pour le catabolisme des glucides à longue chaîne (comme l'amidon) en unités plus petites. L'amylase est également synthétisée dans de nombreuses espèces de fruits pendant leur maturation, ce qui les rend plus sucrés, et aussi durant la germination des grains de céréales. Elle joue un rôle essentiel dans l'amylolyse (ou hydrolyse) de l'amidon de malt d'orge, processus nécessaire à la fabrication de la bière, ainsi que dans l'hydrolyse du glycogène, permettant sa transformation en glucose.
Il y a deux iso-enzymes de l'amylase : l'amylase pancréatique et l'amylase salivaire. Elles se comportent différemment au focusing isoélectrique, et peuvent être séparées en testant par les anticorps monoclonaux spécifiques. La ptyaline ou amylase salivaire est une substance qui existe dans la salive.
L'alpha-amylase brise les liens α(1-4)glycosidiques à l'intérieur des chaînes de l'amylose et de l'amylopectine pour ultimement donner des molécules de maltose (disaccharides de α-glucose). Elle ne peut attaquer que les amidons hydratés et cuits. Possède un site de liaison à l'émail donc participe à l'élaboration de la pellicule acquise exogène. Se lie avec affinité au Streptococcus viridans (en) ce qui conduit à sa clairance ou à son adhésion selon que l'amylase est en solution ou adsorbée à la surface dentaire. L'amylase liée à une bactérie conserve environ 50 % de son activité enzymatique. La bactérie liée à l'amylase peut donc fermenter le glu que celle-ci produit en acide organique.
Epilage enzymatique
Peptidases
Stabilité hydrothermale
Tests d'efficacité
Wet-blue (tannage)Peau tannée au chrome (le chrome donne une couleur bleue)Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Preparation of skin or hide for tanning involves several unit processes/operations. This results in the generation of significant quantity of solid and liquid wastes, which is of major concern for the leather fraternity. However, several alternate technologies are available to address this issue. One of the well explored systems is application of enzymes in conventional leather processing. In the present research, application of bi-functional enzyme-fibrozyme (mixture of protease and amylase) for leather processing was studied. The present study relies upon the characteristic evaluation methods to ascertain the efficiency of enzymes in unhairing and fiber opening. Initially, various concentrations of enzymes were applied to coin hides by drum method. In this approach, 3.5% of fibrozyme is optimized for efficient removal of hair and proteoglycans. This is based on the organoleptic evaluation of enzyme treated pelts. The efficiency of enzyme was primarily evaluated th rough staining technique. Moreover, physical strength parameters were measured to assess the impact on fibers due to enzyme treatment. Morphological evaluation was carried out to confirm that there is no coalescent or distortion of fibers after enzyme treatment. Hydrothermal stability of experimental wet blue leather was found to be 108°C, which confirms better exhaustion and fixation of chromium. The study provides an avenue for integrated enzymatic dehairing and fiber opening using a single formulation of protease and amylase. Note de contenu : - EXPERIMENTAL : Materials - Quantification on the release of protein, proteoglycan processes - Staining techniques - Chrome tanning - Determination of shrinkage temperature - Post tanning process - Evaluation of physical and organoleptic properties of leathers - Scanning electron microscopic (SEM) analysis of processed leathers
- RESULTS AND DISCUSSION : Optimization of enzyme application - Proteoglycan release after enzyme treatment - Histological examination of the control and experimental pelts - Stratigraphic distribution of chromium in wet blue leathers - Visual assessment of wet blue leathers - Physical characteristics of crust leather - Organoleptic properties of crust leathers - Scanning electron microscopy evaluationEn ligne : https://drive.google.com/file/d/1fz3aVx9CIh-uOa3-iBT6_t2lMiVVwJhm/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=27327
in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXI, N° 12 (12/2016) . - p. 455-460[article]Réservation
Réserver ce document
Exemplaires (1)
Code-barres Cote Support Localisation Section Disponibilité 18529 - Périodique Bibliothèque principale Documentaires Disponible PermalinkThe changes in fibre structure of ox hide on enzyme unhairing and tanning as sole leather / R. S. Andrews in JOURNAL OF THE SOCIETY OF LEATHER TRADES' CHEMISTS, Vol. 50, N° 6 (06/1966)
PermalinkThe characterisation and depilation effect of extracellular proteases of streptomyces sp. TYQ1024 / Chufan Cai in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 106, N° 3 (05-06/2022)
![]()
PermalinkUnhairing of bovine skin with fungal enzymes by immersion and spread throughout the epidermis / Maria Laura Garro in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 103, N° 1 (01-02/2019)
![]()
PermalinkUnhairing with enzymes / A. Crispim in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 87, N° 5 (09-10/2003)
![]()
PermalinkA way to reduce injury to skin in enzymatic unhairing / Jian Song in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 99, N° 3 (05-06/2015)
![]()
Permalink