January 2019 Abstracts

Mechanical and Water Interaction Properties of Polymeric Films Produced with Starch and Gelatin Extracted from Leather Waste as Affected by Different Composition

by Bianca Santinon Scopel, Laís Bavaresco, Júlia Mascarello, Aline Dettmer and Camila Baldasso

In this work, gelatin extracted from chromed leather wastes (CLW) was used to produce polymeric films with starch. Different compositions (glycerol or sorbitol as plasticizers, 0, 10 and 20% of plasticizer and 6.4, 8.0 and 9.6 g of starch for each 2.4 g of gelatin) were evaluated. Water solubility ranged from 17 to 28% and elongation at break from 6.5 to 133.8%. The opposite effect was noticed for tensile strength. Small amounts of chromium (2.4 – 2.9 mg/kg of film) would allow the films application in agriculture, where nitrogen released after films degradation would act as a nutrient.

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Machine Vision Inspection System for Detection of Leather Surface Defects

by Malathy Jawahar, K Vani and N K Chandra Babu

Leather quality inspection is very important in assessing the effective cutting value that can be obtained from the leather. Current practice involves an expert to inspect each piece of leather individually and detect defects manually. However, such a manual inspection is highly subjective and varies quite considerably from one assessor to another. Often this subjectivity leads to dispute between the buyer and the seller of the leathers and hence attempts are made to automate this. Automatic leather defect classification is a challenging research problem due to the difficulties that arise when segmenting defects from the leather background and determining the characteristics that describe the defects objectively. The present study describes application of machine vision system to capture leather surface images and the novel multi-level thresholding algorithm to segment defective and non-defective regions of leather followed by texture feature extraction to objectively quantify the leather surface defects. A dataset consisting of 90 leather images comprising 20 good leather and 50 defective samples has been used in the study. Experimental results on the leather defect image library database achieved an accuracy of 90% using neural network as classifier, confirming potential of using the proposed system for automatic leather defect classification.

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Antioxidant Activity of Keratin Hydrolysates Studied by DSC

by Ján Matyašovský, Ján Sedliacik, Peter Šimon, Igor Novák, Tomasz Krystofiak, Peter Jurkovic, Peter Duchovic, Mariana Sedliaciková, Zuzana Cibulková, Matej Micušík and Angela Kleinová

Due to the high content of thio-aminoacids, (i.e., methionine and cysteine) and the structural intermolecular disulfide bonds, this study has focused on new biopolymer keratin antioxidants. The antioxidant activity of keratin hydrolysates in polyethylene glycol (PEG) matrix has been studied using the differential scanning calorimetry (DSC) under non-isothermal conditions. The experimental results have been evaluated and kinetic description of the oxidation induction periods have been carried out using the Bethelot-Hood temperature function. The length of induction periods has been assessed for all temperatures using the kinetic results. In order to compare the stabilizing effect of keratin hydrolysates, protection factors and antioxidant effectiveness have been calculated. The results have shown that the antioxidant activity of keratins strongly depends on the hydrolysis process. The protection factors decreased with increasing temperature and decreasing concentration of keratin. Based on our previous experience, we propose that the qualitative trend presented in this work can also be applied for other matrices than PEG. Keratin hydrolysates and their modifications with antioxidant properties significantly reduced formaldehyde emissions from urea-formaldehyde adhesives.

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Insights into the Molecular Composition of the Skins and Hides used in Leather Manufacture

by Rafea Naffa, Catherine Maidment, Geoff Holmes and Gillian Norris

Increasing demand for information about the effects of the beamhouse processes on animal skins and hides led to the need to determine the differences among different animal skins and hides at molecular level which results in significant changes in their strength. This is a comprehensive study of the molecular components of four animal skins commonly used to manufacture shoes, clothing and furniture to identify common indicators of skin strength. First, the strength of each species was assessed using tear strength and the denaturation temperature. Then the concentration of the following molecular compounds: amino acids, natural collagen crosslinks and glycosaminoglycans (GAGs) were determined. Significant differences in their molecular compositions were found particularly the types and amount of the natural collagen crosslinks which are known to be essential for skin strength. We found that sheep skin contained the lowest collagen content and highest GAG concentrations compared to goat and deer skins and cow hide. To the best of our knowledge, this is the first time where the collagen crosslinks of skin and hide of different species are measured and compared. This study shows that different species have different underlying molecular composition of skins and hides resulting in strength differences. This understanding will help to modify the current leather processing protocols to produce stronger leather.

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