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Session 1 (Wednesday)

Session chair: Hurlow, Elton, Dr (Buckman Laboratories, N.V., Memphis, US); Yu, Thomas, C. J., (Jollity Enterprise Co Ltd, Taipei, Taiwan)
Shortcut: S1
Date: Wednesday, 26 June, 2019, 10:30 AM – 11:45 AM
Room: Hall 1/2
Session type: Oral


Click on an contribution to preview the abstract content.

10:30 AM S1-01

Fine hair on American bovine leathers (#108)

L. A. Zugno1, A. Rhein2

1 Buckman , Memphis, Tennessee, United States of America
2 Tyson Foods, inc., Dakota Dunes, South Dakota, United States of America


Fine hair is the biggest seasonal challenge for bovine leather production in the United States. The origin, timing and severity of the fine hair problem can be unpredictable and vary from year to year. Seasonal changes on the hair growth cycle are prompted by the lower temperature from fall to winter; the cow hair increases in amount, length and thickness.  This problem is very old and has increased in intensity due to changes in the leather manufacturing process, cattle breeding conditions and breed diversity. The amount of fat and thickness of the hide also play important roles.  The extent of the problem has not been documented and is not fully understood by the scientific community.


The presence of fine hair (residual hair) on the wet blue and final leather are a cause of downgrading the leather. If the wet blue has fine hair, it cannot be removed in further processing in crust or finishing. Some leather types can tolerate more fine hair than others.


In this paper we will conduct a scientific evaluation of the fine hair on American bovine hides, wet blue and finished leathers through cross sections and stains, optical and electron microscope observations. We will include measurements of hair thickness and hair depth inside the hide. The work will compare sulfide and oxidative unhairing of winter hides, characterize and show the details of the fine hair through cross sections, and offer indicative measures to minimize the problem.


Information from the largest wet blue manufacturer in the US with four tanneries will provide insight on the fine hair seasonality, types of breeds and cattle displacement temperature ranges and will discuss adaptive changes needed in the “Winter” time to control the fine hair.


1) scientific review and evaluation of the problem of fine hair though cross sections and stains, optical and electron microscopy observations

2) evaluate the fine hair on sulfide and oxidative unhairing; providing indicative measures to minimize the problem

3) characterize the seasonality of the fine hair problem regarding the types of breeds, displacement temperature ranges and adaptative changes to control the fine hair

Keywords: Fine hair, American hides, leather downgrading
10:45 AM S1-02

Biotechnology for environmently-friendly leather production (#297)

J. Y. Liu1, G. Holmes1

1 New Zealand Leather and Shoe Research Association (LASRA), Palmerston North, New Zealand


The leather industry has been challenged to reduce its environmental impact, for example, by producing eco-friendly products with inherent biodegradability using less polluting chemicals. Conventional depilation of hair and wool consumes a large amount of lime and sodium sulphide, which poses a serious waste disposal concern. Volatile organosulphur compounds remaining in leather products may provoke an unpleasant odour and be the cause of a deterioration in indoor air quality. Traditional leather production also generates tanned waste which cannot be readily degraded by microorganisms.

LASRA research is guiding the application of biotechnology to help the New Zealand leather industry develop environmentally sustainable leather processes, replacing hazardous chemicals with microbial enzymes. Using 16S rRNA gene sequencing, we have isolated and identified a number of indigenous bacteria from the leather industry environment which are being adopted to develop benign leather processing technologies. We discovered a strain of Stenotrophomonas spp. with significant and beneficial proteolytic activity in a tannery sludge. The identified strain not only displays collagenase activity but also the ability to reduce hexavalent chromium to trivalent chromium, making it an ideal candidate for biodegradation of tanned waste. We also isolated and identified several Bacillus spp. strains from a biofilter used in a leather manufacturing plant which exhibited sulphide oxidation activity, which are being applied in bioremediation of volatile organosulphur compounds emitted by leather products. Recently we revisited the natural autolytic processes of degradation of untreated pelts to guide a natural depilation method without any need for additional chemical treatment. The characterisation of the bacteria isolated from the skins showed the alkaline protease production activity responsible for the observed nature unhairing. We found that in controlled experiments the wool could be removed completely from follicles after 2 days, without obvious damage and leathers could be processed with organoleptic and mechanical properties comparable to conventionally processed counterparts. With the mechanisms revealed, the natural depilation can be controlled to become more reliable and reproducible across a range of conditions. Our current work is focused on the development of solid-state fermentation using skin and leather waste as a culture medium to produce the required enzymes to make biological leather production practical and reproducible. Our research is aimed at enabling the NZ leather industry to produce high-quality leather products with a much-reduced environmental footprint.


  1. Indigenous bacteria have been isolated and identified from the leather industry environment by the application of 16S rRNA gene sequencing.
  2. Biodegradation of tanned waste and bioremediation of volatile organosulphur compounds are being developed.
  3. The mechanism of natural depilation has been revealed and the application of enzymatic depilation can become practicable by using solid-state fermentation.


Keywords: biotechnology, sustainability, biodegradation, bioremediation, enzymatic depilation
11:00 AM S1-03

The Hunt for Red Microba: Identifying the microbial agents in "red heat" contamination of salt-cured bovine hide (#300)

S. Grace1, M. Ahn2, M. L. Patchett1, G. E. Norris1

1 Massey University, School of Fundamental Sciences, Palmerston North, New Zealand
2 NZ Leather & Shoe Research Association, Palmerston North, New Zealand


“Red heat” is an industry term that describes the appearance of mostly red-pink coloured macroscopic microbial colonies on salt-cured hides and skins.  Red heat-affected stock is undesirable as the resultant leather often shows obvious defects; but why this contamination is only superficial in other instances remains unclear.  Previous work has focused on pigmented halophiles (‘salt-loving’ microbes) isolated from curing salts as the primary culprit.  However, the identity of causative agents remains unspecified.  Also, the involvement of non-pigmented microbes, and of microbes native to hides and skins, could be better understood.  Thus, an investigation of the microbial communities that inhabit untreated bovine hide, curing salt, unaffected salt-cured bovine hide, and red heat-affected cured hide is proposed to uncover the microbial agents responsible for this contamination.  This project aims to define these microbial communities using both a culture-dependent and –independent approach.  Methods of microbe identification focus on marker gene amplification and sequencing.  This is in contrast to earlier work which was restricted solely to phenotypic analyses.  The 16S ribosomal RNA gene marker is used to identify members of Bacteria and Archaea, while the 18S and ITS2 regions of the fungal ribosomal RNA operon are targeted to detect fungi.  Metagenomic amplicon sequencing using the Illumina MiSeq platform employs these same markers to determine taxonomic composition and relative abundance.  Preliminary results from culturing identified different dominant species in curing salts screened for microbial growth.  In agreement with earlier culture-based studies, these isolates were mostly pigmented, highly salt-tolerant members of the halophilic archaea of family Halobacteriaceae, as determined by marker gene sequencing.  However, in agreement with more recent work within food preservation technology, non-pigmented isolates of halophilic archaea of genus Natrinema and bacterial genus Chromohalobacter were also found.  It was also revealed that non-pigmented, quick-growing, salt-tolerant, proteolytic microbes were easily cultured from red heat-affected hide, most of the isolates were identified by marker gene sequencing as bacterial Pseudomonas halophila or Salicola.  To determine red heat-causing microbes, future work involves the screening of isolates for extracellular enzyme activity; the most likely cause of red heat-associated damage.  Sterile-salted hide samples will be inoculated with selected individual and combinations of isolates, and then further examined using confocal microscopy to check for reproducibility of red heat-associated damage. 


Different microbial species are found in different curing salts. 

Not all microbes involved in "red heat" contamination are pigmented.

Keywords: halophiles, red heat, microbiome
11:15 AM S1-04

Structure and tanning properties of dialdehyde carboxymethyl cellulose: Effect of degree of substitution (#94)

Y. Yi1, W. Ding1, C. Huang1, Y. - N. Wang1, 2, B. Shi1, 2

1 Sichuan University, National Engineering Laboratory for Clean Technology of Leather Manufacture, Chengdu, China
2 Sichuan University, Key Laboratory of Leather Chemistry and Engineering, Ministry of Education, Chengdu, China


Developing novel tanning agents from renewable biomass is regarded as an effective strategy for sustainable leather industry. In this study, a series of dialdehyde carboxymethyl cellulose (DCMC) were prepared by periodate oxidation of carboxymethyl cellulose (CMC) with varying degrees of substitution (DS: 0.7, 0.9 and 1.2). The structural properties of DCMC were characterized. Size Exclusive Chromatography measurements showed that CMC underwent severe degradation during periodate oxidation, resulting in the decline of weight-average molecular weight from 250,000 g/mol to around 13,000 g/mol. FT-IR analysis illustrated that aldehyde group was successfully introduced into DCMC. The aldehyde group content of DCMC decreased from 8.38 mmol/g to 2.95 mmol/g as the DS rose from 0.7 to 1.2. Interestingly, formaldehyde was found to be produced in DCMC, and its content was 159.4, 151.7 and 38.4 mg/L, respectively when the DS of CMC was 0.7, 0.9 and 1.2, respectively. Further analysis by HPLC found that fructose was formed during oxidative degradation, and was subsequently oxidized to generate formaldehyde. This was in accordance with the fact that higher DS resulted in lower formaldehyde content in DCMC. The whole reaction mechanism is still under investigation at the moment. Tanning trials showed that the shrinkage temperature and thickening rate of DCMC tanned leather decreased as the DS increased. This should be due to the difference in aldehyde content of DCMC. Leather tanned by DCMC-0.7 (DS of CMC was 0.7) had the highest shrinkage temperature of 81°C and thickening rate of 76%. It was noteworthy that the formaldehyde content in DCMC tanned leather was only 0.11-0.40 mg/kg even though DCMC contained a small amount of formaldehyde. In general, we hope the work on dialdehyde tanning agent derived from CMC could provide some essential data for the development of sustainable tanning material and process.


1. Higher degree of substitution (DS) of CMC resulted in lower aldehyde group content of DCMC.

2. The formaldehyde content of DCMC was negatively correlated with DS.

3. The tanning performance of DCMC with lower DS was better.

Table of Contents
This figure illustrates the oxidation reaction of CMC into dialdehyde CMC (DCMC), the formation of formaldehyde from CMC, the effect of DS on aldehyde content and Mw of DCMC, and the tanning performance of DCMCs with varying DS.
Keywords: Tanning, Carboxymethyl cellulose, Degree of substitution, Dialdehyde, Formaldehyde
11:30 AM S1-05

Investigation on Reducing Chromium Quantity in Chromium Containing Wastes of Leather Industry Using Oyster Mushroom (Pleurotus ostreatus) (#289)

E. E. E. Bayramoglu1, A. Özcelik1, M. Çetin2, E. Eren2

1 Ege University, Engineering Faculty Department of Leather Engineering, Izmir, Turkey
2 Ege University, Bergama Vocational High School, Izmir, Turkey



In the leather industry, the shaved wastes after the wet blue phase, which are exposed by the shaving process, are one of the substances that cause environmental pollution for the leather industry. Most of the time, these wastes can be buried and may cause serious environmental pollution. In this study, wet blue shaved wastes to be mineralized to chromium and so prevented oxidise to Cr (VI) by using oyster mushrooms (Pleurotus ostreatus) .Wet blue shaved wastes were mixed with 0.5%, 1%, 1.5% and 2% doses into the growth medium. After the oyster mushroom growth, the consuming of chromium from the growth media and chromium content that uptaken by the mushroom were investigated with in House method / ICP-MS.



-Oyster mushroom degrade the waste

-Oyster mushroom can uptake chromium 

-Oyster mushroom can grow medium where contens chromium

Keywords: waste, wet blue, biodegredation, chromium, Pleurotus spp.