Influence Of Ph And Different Emulsion Components On Stability And Physicochemical Properties Of Canola Oil-In-Water Emulsion
The main objective of the present study was to investigate the effect of pH (5-7), processing conditions (i.e. pressure, cycle and temperature) and main emulsion components (namely, propylene glycol, caseinate sodium, pectin, sodium chloride and canola oil) on the physicochemical properties of so...
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| Format: | Thesis |
| Language: | English English |
| Published: |
2010
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/12364/1/FSTM_2010_5A.pdf |
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| Summary: | The main objective of the present study was to investigate the effect of pH (5-7),
processing conditions (i.e. pressure, cycle and temperature) and main emulsion
components (namely, propylene glycol, caseinate sodium, pectin, sodium chloride
and canola oil) on the physicochemical properties of sodium caseinate-pectin
stabilized emulsions. In this work, the physicochemical emulsion properties assessed
by measuring the zeta-potential, average droplet size, apparent viscosity, turbidity,
and creaming stability were considered as response variables. The results indicated
that the pH and temperature had significant (p < 0.1) effects on all the response
variables studied. The highest creaming stability was observed at pH 5, which was
attributed to the formation of multilayer in the interfacial area. It was found that the
average droplet size increased when pH was increased from 5 to 7. The prepared emulsions showed shear-thinning behaviour at different pH values (5-7). The highest
emulsion viscosity was also observed at pH 5; while it decreased when pH was
increased from 5.5 to 7.
The influence of processing conditions (i.e. pressure, cycle of high pressure
homogenizer and temperature of environment to solubilize the pectin) on the
physicochemical properties of sodium caseinate-pectin stabilized emulsions were
investigated. The results indicated that the independent variables had the most and
least significant (p < 0.05) effect on average droplet size and stability, respectively.
The effect of cycle of the homogenizer was significant (p < 0.05) in all response
variables. The nonlinear regression equations were significantly (p < 0.05) fitted for
predicting the changes in all the response variables with relatively high coefficient of
determination (R2 > 0.825). It was concluded that desirable physicochemical
properties can be achieved when the pressure, cycle, and temperature of the pectin
solution were adjusted to 13 MPa, 3, and 80 ° C, respectively.
It was observed that the physicochemical properties of emulsions were significantly
(p < 0.1) influenced by the concentration of pectin. It could be explained by the fact
that the presence of carboxyl groups (–COOH) in the molecular structure of pectin
provided the proper surface activity in the interfacial area. The pectin molecules
adsorbed to the droplet surfaces and increased the repulsion forces between the
emulsion onto droplets, thereby preventing extensive droplet flocculation. The zeta
potential remained negative in all emulsion samples, possibly because of negatively charged (-COO-) groups presence in the molecular structure of pectin. The second
order regression equations were significantly (p < 0.1) fitted for predicting the
changes in all the response variables with relatively high coefficient of determination
(R2 > 0.7). The results indicated that the emulsion containing 0.9% (w/w) propylene
glycol, 1.0% (w/w) sodium caseinate, 3.0% (w/w) pectin, 0.2% (w/w) sodium
chloride and 15.0% (w/w) canola oil provided the optimum emulsion formulation
with desirable physicochemical properties. The adequacy of response surface
equations was confirmed by indicating no significant (p > 0.1) difference between
the experimental and predicted values. |
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