Abstract: Inulinase from Aspergillus niger was covalently immobilized on magnetic nanoparticles (MNPs/Fe3O4) covered with soy protein isolate (SPI/Fe3O4) functionalized by bovine serum albumin (BSA) nanoparticles. MNPs are promising enzyme carriers because they separate easily under external magnetic fields and have enhanced immobilized enzyme reusability. As MNPs aggregate simply, surface coating strategy was employed. SPI functionalized by BSA was a suitable candidate for nanomagnetite coating due to its superior biocompatibility and hydrophilicity. Fe3O4@SPI-BSA nanoparticles were synthesized as a novel carrier with narrow particle size distribution. Step by step fabrication monitoring of Fe3O4@SPI-BSA nanoparticles was performed using field emission scanning electron microscopy and dynamic light scattering. The results illustrated that nanomagnetite with the spherical morphology was well monodispersed with the diameter of about 35 nm. The average size of the SPI-BSA nanoparticles was 80 to 90 nm, and their zeta potential was around −34 mV. Finally, the mean diameter of fabricated Fe3O4@SPI-BSA NPs was less than 120 nm. Inulinase enzyme from Aspergillus niger was covalently immobilized through gluteraldehyde on Fe3O4@SPI-BSA nanoparticles successfully. Fourier transform infrared spectra and field emission scanning electron microscopy images provided sufficient proof for the enzyme immobilization on the nanoparticles with 80% enzyme loading.
Abstract: Rice bran is normally used as a raw material for rice
bran oil production or sold as feed with a low price. Conventionally,
the protein in defatted rice bran was extracted using alkaline
extraction and acid precipitation, which involves in chemical usage
and lowering some nutritious component. This study was conducted
in order to extract of rice bran protein concentrate (RBPC) from
defatted rice bran using enzymes and employing polysaccharides in a
precipitating step. The properties of RBPC obtained will be compared
to those of a control sample extracted using a conventional method.
The results showed that extraction of protein from rice bran using
enzymes exhibited the higher protein recovery compared to that
extraction with alkaline. The extraction conditions using alcalase 2%
(v/w) at 50 C, pH 9.5 gave the highest protein (2.44%) and yield
(32.09%) in extracted solution compared to other enzymes. Rice bran
protein concentrate powder prepared by a precipitation step using
alginate (protein in solution: alginate 1:0.016) exhibited the highest
protein (27.55%) and yield (6.84%). Precipitation using alginate was
better than that of acid. RBPC extracted with alkaline (ALK) or
enzyme alcalase (ALC), then precipitated with alginate (AL)
(samples RBP-ALK-AL and RBP-ALC-AL) yielded the precipitation
rate of 75% and 91.30%, respectively. Therefore, protein
precipitation using alginate was then selected. Amino acid profile of
control sample, and sample precipitated with alginate, as compared to
casein and soy protein isolated, showed that control sample showed
the highest content among all sample. Functional property study of
RBP showed that the highest nitrogen solubility occurred in pH 8-10.
There was no statically significant between emulsion capacity and
emulsion stability of control and sample precipitated by alginate.
However, control sample showed a higher of foaming capacity and
foaming stability compared to those of sample precipitated with
alginate. The finding was successful in terms of minimizing
chemicals used in extraction and precipitation steps in preparation of
rice bran protein concentrate. This research involves in a production
of value-added product in which the double amount of protein (28%)
compared to original amount (14%) contained in rice bran could be
beneficial in terms of adding to food products e.g. healthy drink with
high protein and fiber. In addition, the basic knowledge of functional
property of rice bran protein concentrate was obtained, which can be
used to appropriately select the application of this value-added
product from rice bran.
Abstract: The effect of cross linking of the protein isolates of
three legumes with the microbial enzyme transglutaminase (EC
2.3.2.13) on the functional properties at different NaCl concentration
was studied. The reduction in the total free amino groups (OD340) of
the polymerized protein showed that TGase treatment cross-linking
the protein subunit of each legume. The solubility of the protein
polymer of each legume was greatly improved at high concentration
of NaCl. At 1.2 M NaCl the solubility of the native legumes protein
was significantly decreased but after polymerization slightly
improved. Cross linked proteins were less turbid on heating to higher
temperature as compared to native proteins and the temperature at
which the protein turns turbid also increased in the polymerized
proteins. The emulsifying and foaming properties of the protein
polymer were greatly improved at all concentrations of NaCl for all
legumes.
Abstract: The present work represents an investigation of the
hydrolysis of hull-less pumpkin (Cucurbita Pepo L.) oil cake protein
isolate (PuOC PI) by pepsin. To examine the effectiveness and
suitability of pepsin towards PuOC PI the kinetic parameters for
pepsin on PuOC PI were determined and then, the hydrolysis process
was studied using Response Surface Methodology (RSM). The
hydrolysis was carried out at temperature of 30°C and pH 3.00. Time
and initial enzyme/substrate ratio (E/S) at three levels were selected
as the independent parameters. The degree of hydrolysis, DH, was
mesuared after 20, 30 and 40 minutes, at initial E/S of 0.7, 1 and 1.3
mA/mg proteins. Since the proposed second-order polynomial model
showed good fit with the experimental data (R2 = 0.9822), the
obtained mathematical model could be used for monitoring the
hydrolysis of PuOC PI by pepsin, under studied experimental
conditions, varying the time and initial E/S. To achieve the highest
value of DH (39.13 %), the obtained optimum conditions for time
and initial E/S were 30 min and 1.024 mA/mg proteins.