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Flow characteristics of a pilot-scale high temperature, short time pasteurizer
1Dairy Processing and Products Research Unit, US Department of Agriculture, Eastern Regional Research Center, Agricultural Research Service, Wyndmoor, PA 19038, USA. ptomasula@errc.ars.usda.gov
Journal of Dairy Science
|September 18, 2004
Summary
Determining the fastest moving particle (FMP) and residence time distribution (RTD) in pilot-scale pasteurizers is crucial. This study validates laboratory equipment for thermal inactivation studies by analyzing flow characteristics.
Area of Science:
- Food Science and Engineering
- Process Engineering
- Dairy Technology
Background:
- Pilot-scale High Temperature Short Time (HTST) pasteurizers are used for thermal inactivation studies.
- Ensuring these systems meet regulatory standards (Pasteurized Milk Ordinance) is essential for data reliability.
- Understanding flow dynamics, specifically Fastest Moving Particle (FMP) and Residence Time Distribution (RTD), is key to validating pasteurizer performance.
Purpose of the Study:
- To develop and present a method for determining FMP and RTD in a pilot-scale HTST pasteurizer.
- To validate if laboratory or pilot-scale HTST apparatus meets Pasteurized Milk Ordinance standards.
- To confirm the suitability of pilot-scale systems for obtaining accurate thermal inactivation data.
Main Methods:
- Utilized tracer studies with brine milk to measure FMP times and RTD.
- Analyzed flow characteristics in both short (nominal 21.5 s) and long (nominal 52.2 s) holding sections.
- Calculated the percentage of back-mixed and plug flow within the holding tubes at 72°C.
Main Results:
- The actual FMP time for the short holding section was 18.6 s and for the long holding section was 36 s at 72°C.
- The short hold section exhibited 45% back-mixed and 55% plug flow characteristics.
- The long hold section demonstrated 91% plug flow and 9% back-mixed flow at 72°C.
Conclusions:
- The study provides a validated method for assessing flow dynamics in pilot-scale HTST pasteurizers.
- Pilot-scale pasteurizers can be reliably used for thermal inactivation studies if their flow conditions are rigorously established.
- Accurate characterization of FMP and RTD is essential for comparing laboratory findings with commercial HTST systems and ensuring regulatory compliance.