Performance Evaluation Of An Agitated Thin Film Evaporator For Pineapple Juice Concentration
Concentration is one of the important operations in food industry with applications ranging from the production of condensed milk, paste and purees from fruits. Using an agitated thin film evaporator allows for the concentration to be undertaken at low temperature and short residence time with re...
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| Format: | Thesis |
| Language: | English |
| Published: |
2004
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/5960/1/FK_2004_71%20IR.pdf |
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| Summary: | Concentration is one of the important operations in food industry with applications
ranging from the production of condensed milk, paste and purees from fruits. Using
an agitated thin film evaporator allows for the concentration to be undertaken at low
temperature and short residence time with reduced heat loss for heat sensitive
material.
The parameters that influence an agitated thin film evaporator process are steam
temperature; product feed rate, vacuum pressure, rotor speed, physical and thermal
properties of the product and the overall heat transfer coefficient. These indicate that
the process is a very complex heat and mass transfer an operation that requires
optimization in order to reduce the cost and maintain the product quality
The overall heat transfer coefficients (U,) of pineapple juices (fresh juice of 11.3,
14.4, 19.9. and 27.3 "Brix) were determined using a laboratory scale agitated thin
film evaporator (ATFE) under different rotational speeds (200, 400, and 600 rpm),liquid flow rates (25, 35, and 45 Ilh), and at constant steam and vacuum pressure.
The Experiments were conducted with water and (U,) for water determined under the
different parameters.
S ~ meq uations to predict the Thermophysical properties of the pineapple juices at
different concentrations were derived from the experimental data (density and
viscosity) and others taken from the literature.
The overall heat transfer coefficients (U,) were determined based on inner heat
surface area. The magnitude of (U,) ranged from 390 to 2700 W / m" CTh. e
performance of the evaporator was evaluated and determined .Some of the pineapple
juices quality parameters before and after concentration were studied for effects of
concentration by ATFE .The juice color was very little changed based on the
Hunter lab values measurements, while the vitamin C contents were decreased by
10.1 %, and 23.13% for the 16.8 and 40.3 "Brix ,respectively |
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