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Title of Thesis
Production, Purification And Characterization Of Carboxymethyl
Cellulase For Food Applications |
Author(s)
Muhammad
Tahir Nadeem |
Institute/University/Department Details
National
Institute of Food Science and Technology / University of Agriculture Faisalabad |
Session
2009 |
Subject
Food
Technology |
Number of Pages
204 |
Keywords (Extracted from title, table of contents and abstract of thesis)
Production, purification, characterization, carboxymethyl, cellulose,
food applications |
Abstract
Agricultural wastes/byproducts have great potential for the
production of value added products with special reference to
enzymes. Two indigenous carbon sources namely, wheat bran and sugar
cane bagasse were used as substrates for carboxymethyl cellulase (CMCase)
synthesis by Aaspergillu niger through submerged fermentation. The
fungus produced highest CMCase activities at 3% level of wheat bran
using 30°C and pH 5 over 96 hrs of incubation. The enzyme was
purified for its further use in food processing. During the
purification process, a 3.05 fold purification of enzyme was
observed after gel filtration. Characterization of purified enzyme
was carried out to find out the most suitable conditions for the
CMCase performance; the best enzyme activity was observed at 50°C
and pH 4.5. The enzyme was quite stable and retained 37% of its
maximum activity at 90°C. The SDS-PAGE of the purified enzyme
revealed its molecular weight as 47.1 kDa. For efficacy purpose, the
enzyme added feeds were given to the broiler chicks in order to
investigate their effects on body performance, feed efficiency and
for safety concerns. The enzymatic treatment exhibited positive
effects on body weight, carcass weight and chest muscle weight.
Non-significant variations in the serum biochemistry and
hematological parameters were observed. After safety evaluation, the
enzyme was employed at various levels in bread preparation.
Different treatments exhibited significant variations in rheological
properties of the dough. The CMCase application in the bread making
process resulted in increased volume (15.45%) up to a level of 250
IU/100g flour (T2) however, excessive dose showed a decreasing trend
for this parameter. The treatment T2 produced bread with specific
volume 3.99 cm3/g in contrast to that of T0 i.e. 3.37 cm3/g. The
external and internal characteristics of bread were also improved by
the enzyme addition. Later, the enzyme application in citrus juice
extraction also showed beneficial effects. Although the enzymatic
treatment had non-significant effect on TSS, density and pH of pulp
and juice however, a momentous reduction in pulp viscosity i.e.
74.79% was observed in T6 (CMCase and pectinase 50 IU/100g each).
Moreover, the treatment T6 gave more clarified juice with 95.70%
transmittance than that of control (78.00%); also resulted in 20.00%
increase in the juice yield with 90.00% juice recovery. The sensory
evaluation of the enzyme treated juice reflected improved taste,
flavor and sweetness however; caused slight color deterioration of
the resulting juice. The purified enzyme was also employed in
carotenoid extraction from citrus peel and the maximum yield
(8.60±0.94 mg/100g peel) was calculated in case of T4 (250 IU of
each enzyme/100g peel). The pigment showed more stability in dark as
compared to light at 30°C. Furthermore, higher pigment loss was
observed at 45°C than that at refrigeration temperature (4°C). It
was also observed that freeze drying of the pigment enhanced its
stability. It is concluded from the present investigation that wheat
bran has a potential for CMCase production that can efficiently be
used in bread production, juice processing and carotenoid
extraction.
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