Characterization of particle and bulk solids of Arabic gum powder at different particle sizes
The use of Arabic gum as a functional food ingredient is growing rapidly. Arabic gum is obtained in the form of gum nodules from the exudation of stems and branches of Acacia Senegal (L.). Particle size is an important factor influencing powder properties and the end product’s quality. However, t...
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| Format: | Thesis |
| Language: | English |
| Published: |
2022
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/114870/1/114870.pdf http://psasir.upm.edu.my/id/eprint/114870/ http://ethesis.upm.edu.my/id/eprint/18195 |
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| Summary: | The use of Arabic gum as a functional food ingredient is growing rapidly. Arabic
gum is obtained in the form of gum nodules from the exudation of stems and
branches of Acacia Senegal (L.). Particle size is an important factor influencing
powder properties and the end product’s quality. However, the food industry
lacks information about the effects of particle size on the handling and
processing of Arabic gum powder. Hence, this study investigated the particle
size effects on Arabic gum powder's physicochemical, flow, rheological, and
stability properties. The gum nodules were washed, dried, and cleaned before
being ground, sieved, and fractionated into five particle size classes. The
fractionation was classified according to its mean diameter (d50), which ranged
from 20 to 1000 μm. The proximate composition analysis confirmed that
particle size significantly affected the moisture and fibre contents of gum
powder. Smaller particles have a higher hygroscopicity, with values of 40%,
indicating that they are more prone to absorbing moisture from their
surroundings. The dissolution analysis discovered that smaller particles
dissolve in water more slowly than larger particles. The swelling index and
emulsion capacity results show that larger particles retained more waterswollen
granules and had a more remarkable ability to form an emulsion with
oil. Meanwhile, morphology analysis discovered that the gum powder had an
irregular shape with rough granule surfaces. On the other hand, a reduction in
particle size from 1000 to 20 μm tends to reduce powder flowability. The
highest Hausner ratio and Carr's index values were found in smaller particles,
indicating poor powder flowability. Larger particles caked more, which is due to
powder segregation during the handling process, with the coarser fraction
dominating the overall caking behaviour of the powders. Furthermore, the
larger particles had the highest effective angle of internal friction values due to
their interlocking effect. Smaller particles had the highest effective angle of wall
friction values, indicating that they will have more difficulty moving along the
wall surface. Rheological analysis discovered that all particle sizes exhibited
shear-thinning behaviour at low shear rates (0.1–50 s-1) and a viscosity plateau
at high shear rates (50–400 s-1). Higher R2 validates the best-fitting power-law
model for describing the aqueous solution's flow behaviour (n) and consistency
index (K). Furthermore, the dynamic mechanical spectra curves revealed that
the storage (G') and loss (G") moduli values increased with frequency,
indicating that the highly concentrated gum exhibited solid-like rather than
liquid-like behaviour. The isotherm curves had sigmoidal shapes and Type III
behaviour, which is typical of sugar-rich products. The Peleg model fits the
equilibrium moisture sorption of gum powder well. With SSE = 0.01, RMSE =
0.014, P = 14.14%, and R2 = 0.999, smaller particles provided the best fitting
accuracy. To summarize, Arabic gum with coarse particles sized 208 to 414 μm
demonstrated greater dissolution time, flowability, elasticity, and stability than
other particle sizes. The ability to predict moisture content during storage under
a variety of conditions can reduce product development costs and cycle time
while also improving shelf life estimation. Furthermore, this comprehensive
study of Arabic gum powder’s physicochemical properties will aid in the
development of food products with the desired texture by allowing for the
selection of a specific particle size. |
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