Mathematical modelling and optimisation of the formulation and manufacture of aggregate food products
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Date
2010-07
Authors
Baş, Nurşin
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Publisher
University College Cork
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Abstract
In this PhD study, mathematical modelling and optimisation of granola production
has been carried out. Granola is an aggregated food product used in breakfast cereals
and cereal bars. It is a baked crispy food product typically incorporating oats, other
cereals and nuts bound together with a binder, such as honey, water and oil, to form
a structured unit aggregate.
In this work, the design and operation of two parallel processes to produce aggregate
granola products were incorporated:
i) a high shear mixing granulation stage (in a designated granulator) followed by
drying/toasting in an oven.
ii) a continuous fluidised bed followed by drying/toasting in an oven.
In addition, the particle breakage of granola during pneumatic conveying produced
by both a high shear granulator (HSG) and fluidised bed granulator (FBG) process
were examined. Products were pneumatically conveyed in a purpose built conveying
rig designed to mimic product conveying and packaging. Three different conveying
rig configurations were employed; a straight pipe, a rig consisting two 45° bends and
one with 90° bend. It was observed that the least amount of breakage occurred in
the straight pipe while the most breakage occurred at 90° bend pipe. Moreover,
lower levels of breakage were observed in two 45° bend pipe than the 90° bend
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pipe configuration. In general, increasing the impact angle increases the degree of
breakage. Additionally for the granules produced in the HSG, those produced at 300
rpm have the lowest breakage rates while the granules produced at 150 rpm have the
highest breakage rates. This effect clearly the importance of shear history (during
granule production) on breakage rates during subsequent processing. In terms of the
FBG there was no single operating parameter that was deemed to have a significant
effect on breakage during subsequent conveying.
A population balance model was developed to analyse the particle breakage occurring
during pneumatic conveying. The population balance equations that govern this
breakage process are solved using discretization. The Markov chain method was used
for the solution of PBEs for this process. This study found that increasing the air
velocity (by increasing the air pressure to the rig), results in increased breakage among
granola aggregates. Furthermore, the analysis carried out in this work provides that
a greater degree of breakage of granola aggregates occur in line with an increase in
bend angle.
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Keywords
Population balance modelling , Breakage , Aggregation , Simulation , Probabilistic theory
Citation
Baş, N, 2010. Mathematical modelling and optimisation of the formulation and manufacture of aggregate food products. PhD Thesis, University College Cork.