Temperature Non-Uniformity During High Hydrostatic Pressure Processing and its Impact on Food Safety
Meenakshi Khuranaa and Mukund V. Karweb
Rutgers University, 65 Dudley Road, New Brunswick, NJ, 08901, USA.
amkhurana@eden.rutgers.edu
bkarwe@aesop.rutgers.edu
ABSTRACT
High Hydrostatic Pressure (HHP) processing is a novel, non-thermal food processing technology for producing safe, high quality food products with minimum detrimental effects of thermal processing such as loss of original flavor and color. During HHP processing, pressures up to 145,000 psi (1000 MPa) may be applied to a food product. The objectives of this research were to carry out numerical simulation of temperature distribution during HHP processing and to quantify its impact on microbial inactivation. During pressurization, the temperature of the pressurizing medium (water) and the temperature of the product can rise by 25° C due to compression heating. This, combined with natural convection cooling at the vessel wall, can lead to nonuniform temperature distribution. The computational fluid dynamics software FLUENT® (6.3) was used to carry out numerical simulation of thermal transport during HHP. The numerical predictions were validated using thermocouples at three locations. The effects of multiple food pouches and an insulating sleeve on the temperature distribution were investigated. The results showed that the temperature non-uniformity arises in water due to natural convection and heat loss to the vessel wall. The nonuniformity increased with increasing the initial temperature. Comparison of experimental and numerically predicted data showed some disagreement at higher initial temperatures. The comparison became better after the water added during pressurization was included in the simulation. The location of the food pouch in the vessel was found to affect the temperature distribution within water and within the pouch. The effect of non-uniform temperature on inactivation of microorganisms was found to be significant. Adding an insulation sleeve in the vessel reduced the temperature non-uniformity. The results obtained from this research can be used to estimate the process uniformity of combined high pressure high temperature treatment used in making commercially sterile products.
Full Text (PDF)
|
