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FLOW BEHAVIOUR OF CONCENTRATED ORANGE JUICE
1Department of Food and Biotechnology, Technion, Israel Institute of Technology, Haifa.
Journal of Texture Studies
|April 4, 2017
Summary
Orange concentrate exhibits non-Newtonian fluid properties, including yield stress and time-dependent behavior. High shear rates irreversibly damage its structure, partly due to pulp disintegration, while temperature affects flow properties.
Area of Science:
- Food Science
- Rheology
- Fluid Dynamics
Background:
- Orange concentrate (60-65° Brix) is a complex fluid.
- Understanding its flow behavior is crucial for processing and storage.
- Non-Newtonian properties, yield stress, and time-dependency are key characteristics.
Purpose of the Study:
- To investigate the rheological properties of orange concentrate and its fractions.
- To determine the impact of shear rate and temperature on flow behavior.
- To understand the role of pulp and pectin in the fluid structure.
Main Methods:
- Rheological measurements were performed on orange concentrate, pulpless concentrate (serum), and depectinized serum.
- Studies included varying shear rates and temperatures.
- Analysis focused on yield stress, time-dependent behavior, and structural changes.
Main Results:
- Orange concentrate exhibits irreversible structural changes under high shear rates, linked to pulp disintegration.
- Pulpless concentrate shows non-Newtonian behavior dependent on pectin concentration.
- Depectinized serum behaves as a Newtonian fluid.
- Temperature significantly influences the flow properties of all tested materials.
Conclusions:
- The viscous structure of orange concentrate is sensitive to high shear rates.
- Pectin concentration is a critical factor for the non-Newtonian behavior of orange serum.
- Temperature is a significant variable affecting orange concentrate rheology.