• Enzymatic dehairing process takes short period as compared to chemical
dehairing, i.e. the lime–sodium sulphide process takes about between 48 and
72 h, while the enzymatic dehairing process is accomplished within 3 and
12 h [15].
• The process eliminates the problem of waste disposal because by-products like
hairs, wool, flesh, etc. can be recovered during or after dehairing.
• Enzymes are not persistent and can be readily inactivated and biodegraded.
• The process simplifies pre-tanning operations by cutting down one step, viz.,
bating since proteolytic enzymes are capable of removing all the hair.
• Use of enzymes greatly cuts down pungent smell and air emission.
• The process results in significant reduction in total solids, dry sludge and chemical oxygen demand in the effluent due to reduced use of chemicals.
• Treating hide/skins with enzymes produces soft, tough and pliable leather of high
quality with greater surface area.
• Using the enzyme-based process creates an ecologically conducive atmosphere
for the workers.
7.2.3 Fleshing
Fleshing is the mechanical scraping of the unwanted organic material from the hide
and skins (connective tissue, flesh, fat, etc.). This process can be executed before
soaking, after soaking, after liming or after pickling. In conventional leather
processing, the process of fleshing is called green fleshing if the process is done
before liming and dehairing. If fleshing is effected after liming and dehairing, it is
called lime fleshing [5]. Sheepskins may be fleshed in the pickled state. Fleshing
operations give rise to an effluent containing fatty and fleshy matter in suspension. If
green fleshing is adopted, proteolytic and lipolytic enzymes can be utilized to
hydrolyse fleshy matter to generate valuable products and recover biomolecules
since the waste are not contaminated with sulphide.
7.2.4 Splitting
The uneven thickness of hides and skins is balanced out by mechanical splitting
horizontally into a grain layer and flesh layer. Splitting is undertaken using splitting
machines, fitted with band knife. Splitting can either be done in limed state or in the
tanned condition [5]. This process generates huge quantities of flesh and fat waste,
which can be solubilized and hydrolysed by use of proteolytic and lipolytic enzymes
as described in fleshing to section.
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W. C. Wanyonyi and F. J. Mulaa
dehairing, i.e. the lime–sodium sulphide process takes about between 48 and
72 h, while the enzymatic dehairing process is accomplished within 3 and
12 h [15].
• The process eliminates the problem of waste disposal because by-products like
hairs, wool, flesh, etc. can be recovered during or after dehairing.
• Enzymes are not persistent and can be readily inactivated and biodegraded.
• The process simplifies pre-tanning operations by cutting down one step, viz.,
bating since proteolytic enzymes are capable of removing all the hair.
• Use of enzymes greatly cuts down pungent smell and air emission.
• The process results in significant reduction in total solids, dry sludge and chemical oxygen demand in the effluent due to reduced use of chemicals.
• Treating hide/skins with enzymes produces soft, tough and pliable leather of high
quality with greater surface area.
• Using the enzyme-based process creates an ecologically conducive atmosphere
for the workers.
7.2.3 Fleshing
Fleshing is the mechanical scraping of the unwanted organic material from the hide
and skins (connective tissue, flesh, fat, etc.). This process can be executed before
soaking, after soaking, after liming or after pickling. In conventional leather
processing, the process of fleshing is called green fleshing if the process is done
before liming and dehairing. If fleshing is effected after liming and dehairing, it is
called lime fleshing [5]. Sheepskins may be fleshed in the pickled state. Fleshing
operations give rise to an effluent containing fatty and fleshy matter in suspension. If
green fleshing is adopted, proteolytic and lipolytic enzymes can be utilized to
hydrolyse fleshy matter to generate valuable products and recover biomolecules
since the waste are not contaminated with sulphide.
7.2.4 Splitting
The uneven thickness of hides and skins is balanced out by mechanical splitting
horizontally into a grain layer and flesh layer. Splitting is undertaken using splitting
machines, fitted with band knife. Splitting can either be done in limed state or in the
tanned condition [5]. This process generates huge quantities of flesh and fat waste,
which can be solubilized and hydrolysed by use of proteolytic and lipolytic enzymes
as described in fleshing to section.
210
W. C. Wanyonyi and F. J. Mulaa