BIOTECHNOLOGY LETTERS
Volume 14 No.6 (june 1992) pp.531-534
Received as revised 13th May
AN E N Z Y M E
B I O T E C H N O L O G Y FOR THE T O T A L
OF L E A T H E R W A S T E S
UTILIZATION
P . G . D a l e v ~ L . S . Simeonova
L a b o r a t o r y of New P r o t e i n S o u r c e s , F a c u l t y of B i o l o g y ,
U n i v e r s i t y o f S o f i a , 8 b u l . Dragan T s a n k o v ,
1421 S o f i a , B u l g a r i a
SUMMARY
The i s o l a t i o n
of p r o t e i n and f a t f r a c t i o n s
from a
waste of t h e l e a t h e r i n d u s t r y i s d i s c u s s e d . T h i e r e p r e s e n t s the main waste of l e a t h e r p r o d u c t i o n and g i v e s r i se to problems of e c o l o g i c a l and e c o n o m i c a l n a t u r e . A
m i d d l e c a p a c i t y f a c t o r y d e p o s i t s about 30 t o n e s of t h e
so c a l l e d c a r r i o n , a s o u r c e f o r the p r o d u c t i o n of a b o u t
3 t u s e f u l p r o d u c t s - p r o t e i n and f a t .
INTRODUCTION
The c a r r i o n remains a f t e r t h e s p l i t t i n g
of t h e l e a t h e r b e f o r e t a n n i n g . I t c o n s i s t s of t h e l o w e s t l a y e r of
the derma and some of the u n d e r l y i n g f a t t y t i s s u e . I t i s
c h a r a c t e r i z e d w i t h a h i g h s a l t c o n t e n t (sodium c h l o r i d e ,
c a l c i u m h y d r o x y d e and o t h e r c o n s e r v a n t s ) . I t s o r g a n i c material
c o n s i s t s m a i n l y of p r o t e i n and l i p i d e .
The amino
a c i d c o m p o s i t i o n ( m a i n l y s h o r t aBino a c i d r e s i d u e s ) of
the p r o t e i n i s t y p i c a l f o r c o l l a g e n s . E f f o r t s f o r t h e
utilization
of t h i s waste a r e c o n n e c t e d w i t h washing
w i t h a c i d s and a f o l l o w i n g e x t r a c t i o n o r p r e s s i n g a t
h i g h t e m p e r a t u r e s (Tkac et e l . , 1987; M d i n a r a d z e , 1987;
Raumond,1975). The known p r o c e d u r e s employ c o s t l y e q u i p ment and l o n g p r o c e s s i n g . Here we r e p o r t r e s u l t s from
s t u d i e s of a p r o c e s s which r e q u i r e s en o r d i n a r y e q u i p ment and consumes minimum t i m e . I t r e s u l t s i n the p r o d u c t i o n of c o m m e r c i a l p r o d u c t s of h i g h v a l u e .
MATERIALS AND HETHODS
R e a g e n t s . H y d r o c h l o r i c a c i d ( t e c h n i c a l grade c o n t a i n i n g heavy m e t a l s and t o x i c a d m i x t u r e s w i t h i n t h e l i m i t s of t h e r e q u i r e m e n t s f o r f o d d e r p r o d u c t s ) , tap w a t e r
and a n a l y t i c a l
grade c h e m i c a l s were used. A l k a l i n e p r o t e i n a s e B 72 from Bac. S u b t i l i s ,
of a c t i v i t y
50 000 U I / g
from the r e g u l a r p r o d u c t i o n of the p l a n t f o r enzymee,
B o t e v g r a d , B u l g a r i a was employed.
I n s t r u m e n t s . The e x t r a c t i o n and t h e o t h e r p r o c e d u -
531
res were carried
o u t on t h e a v a i l a b l e
installations
of
leather
factories
and e s p e c i a l l y
for the production
of
glue.
Raw materials. As a raw material we u s e d t h e w a s t e
from the regular production of e leather factory with a
content of water 75 - 90 %, protein (of dry mass) 35 60 %, lipids 10 - 35 %, polysaccharides 10 - 15 %. It
was produced from cattleleather.
Analytical procedures. The content of protein, lipids, polysaccharides, water end others were determined
according to the methods for analysis of foodstuffs (Lebedev, 1969). The amino acid content was determined with
HICROTECHNA AAA 881 a n ~ l y s e r a f t e r
hydrolysis
w i t h 6N
HC1 f o r 24 h o u r s a t 1 1 0 o c .
RESULTS AND DISCUSSION
The w a s t e was c u t
with
water,
total
for
r e was r a i s e d
with
All
water
liquid
The h e a v y
the
centrifuge.
as a f i n a l
for
ready
was m i x e d w i t h
kg f o r
66~
every
for
gested
is
data
for
is
a dark-brown
content
the
three
The t h r e e f o l d
complete
protein
(pH o f
glue
to
proteinase
the
twice
time.
on a
consisted
use p r o d u c t .
according
to
produce
glue
material
was a d d e d
was c o n t i n u e d
material
was 7 -
a fluidized
(2,5
at
55
8).The
di-
drier.
The d r y
a characteristic
35 - 45 %~ and 4 -
"Protein
smell
8 % fat.This
Concentrate".The
analytical
given
1.
products
are
extraction
(glue)
to
The i n s o l u b l e
mass w i t h
solubilization
fraction
of
digestion
in
of
fraction
was p r o c e s s e d
alkaline
the
and an i n s o l u b -
30 min each
a ready
use p r o d u c t .
was d r i e d
termed
is
production
and
2 hours
end a p r o t e i n
product
to
water,
material
product
fraction
the
tone)
It
The l i q u i -
and s e p a r a t e d
The l i g h t e r
tallow.
(aqueous)
procedure
for
mixtucomp-
was e x t r a c t e d
were collected
cattle
occured.
fraction
the
conditions
a liquid
same t e m p e r a t u r e
fraction
lipids-
to
the
temperatu-
temperature
these
and
(0,02%of
and t h e n
material
was s e p a r a t e d
The c u t
a reactor
enzyme
this
Under
the
and w a s h e d
water.
into
with
At
of
the
liquid/liquid
-
90~
The i n s o l u b l e
at
with
stirring
60 min m o r e .
material
fraction.
60~
continuous
liquidification
le
of
50 -
to 80-
r e was s t i r r e d
dified
10 cm p i e c e s
was t r a n s f e r e d
60 min a t
mass) w i t h
lete
5 -
2 - 4 % HC1 and a g a i n
end w a s h e d m a t e r i a l
heated
into
of
the
on t a b l e
waste
of the collagens
with
high
532
protein
ensures
almost
to produce
content
a
(91 -
Table 1 . C o m p o s i t i o n of the f r a c t i o n s
from the l e a t h e r waste
Y i e l d Water P r o t e i n L i p i d s
Ash P o l y s a c c h a r i d e s
% o f the
% of t h e d r y w e i g h t
t o t a l mass
Fraction
Waste
Glue
100
5-9
73-87
.~-5~
35-60
9i-93
10-35
2-3
5-7
3-5
4-6
4-12
4-8
2-6
35-45
.
3-8
5-9
9 3 - 9 5 0[_2,-0,4______
~
101 -
14
3
12 -
25
Protein
concentr.
Tallow
93 %).
In aqueous s o l u t i o n
quality.
it
possesses a s t r o n g
Complete s o l u b i l i z a t i o n
eved by the enzyme d i g e s t i o n .
c o n t e n t and the b i o l o g i c a l
and d e f i n e d
Sofia
in
harmful
effects.
in
C e r e a l s and Fodder i n
residues)
-
this
and o t h e r
c o m p o s i t i o n of
the p r o t e i n
table
later)
The e x p e r i m e n t s on r a t s
The amino a c i d
the main p r e s e n c e of c o l l a g e n s
the p r o t e i n
was i n v e s t i g a t e d
74 - 76 %, no t o x i c a l
the g l u e and i n
amino a c i d
to
be r e p o r t e d
can be used as f o d d e r .
showed d i g e s t i b i l i t y
(it
for
gluey
the r e s i d u e was a c h i -
According
by D r . E . P o p o v - d a t a w i l l
fraction
teins
of
value
the I n s t i t u t e
-
(high
the p r o -
concentrate
content
shows
of s h o r t
2.
Table 2. Amino a c i d c o m p o s i t i o n of t h e l e a t h e r waste
and o f i t s f r a c t i o n s
(grams amino a c i d p e r
100 g p r o t e i n )
Amino
Pro-
acid
Waste
Glue
rein
concontr,
Asp
8,67
7,34
Thr
3,83
Ser
Pro-
Amino
acid
Waste
Glue
tceoinncentr.
1,05
Moth
1,19
1,31
1,39
2,37
6,29
lie
3,19
2,13
2,67
5,05
5,52
6,49
Leu
5,17
3,68
4,74
Glu
10,76
10,49
10,76
Tyr
2,58
1,42
2,67
Fro
11,67
13,15
12,38
Fhe
3,83
2,50
3,08
Gly
17,36
22,88
19,01
His
2,43
2,13
~,80
Ala
8,82
9,46
8,63
Lye
4,71
3,92
3,69
Val
4,83
3,08
4,26
Arg
5,99
8,62
8,09
The c h a r a c t e r i s t i c
of
the c o m m e r c i a l
the B u l g a r i a n
article
State
data of
the t a l l o w
"animal
Standarts),
533
tallow"
are typical
(according
namely= c o l o u r
-
to
yellow;
consistence
specific;
fat
admixtures
lue
-
hard,
10
content
- 2,4 ~
its
in
melting
can
sticky
data
mal g l u e "
- 93 -
fraction
content
strongly
ristic
structure
95 ~ ;
point
-
smooth;
water
- 0,5
smell
-
- 40 - 4 5 ~
-
1,5 ~;
acid
va-
30.
-
The main
protein
greasy~
are
it
- the glue
not
qualities.
typical
will
be used
of
in spite
as
fodder
As f a r
the
the high
because
as i t s
commercial
be used as a h i g h
of
of
characte-
article
"ani-
glue
mainly
quality
carpentry.
CONCLUSION
Using
a simple
red for
the
leather
industry
procedure
complete
utilization
and f o r
ducts,
namely:
animal
fodder
and a n i m a l
a technology
of
the
the production
glue,
protein
can be o f f e -
main w a s t e
of
of
pro-
usefull
concentrate
for
tallow.
REFERENCES
1.
Lebedev V. and A . U s o v i c h ( 1 9 6 9 ) . H e t h o d s
gation of food, Publ. "Nir",
Hoscow.
2.
H d i n a r a d z e T. ( 1 9 8 7 ) .
Publ. "Agropromizdat",
3.
Raumond I .
4.
Tkac 0 . , F . P e c h a , H.Hanas and A . K o m a r e k
L e d e r , No 6 , p . 1 1 6 - 1 2 2 .
(1974).
Processing
Hoscow.
OALCA 6 9 ,
534
of
No 5,
for
animal
investi-
wastes.
p.195.
(1987).
Das