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Process Validation in Food Industry

What is Process Validation?

Process validation is establishing documented evidence which provides a high degree of assurance that a specific process will consistently produce a product meeting its pre-determined specifications and quality characteristics. 

In another words, Process validation is an action providing in accordance with the principles of Good Manufacturing Practice, that any procedure, process, equipment, activity or system actually leads to the expected results. The expected results are defined by the user, these could be to inactivate the microbial growth, to preserve the appearance with desirable colour, texture & taste etc.

Thermal Processing

Heat Process Method or Thermal Process Method is the most common method use in food production & preservation. There are many parameters need to be measured before & after the implement of Thermal Processing Method.  

Firstly, vacuum in packed foods especially for all canning operations before any thermal process. Vacuum is a measurement of the extent to which air has been removed from the container.   This is important because the air molecules trapped inside packaging could build up the pressure during thermal processing.  It will exert a lot of pressure onto the lid and seams of the container. 

Secondly, is the Initial and the final temperature of the products.  Initial temperature refers to an initial temperature of the products before any thermal processes or freezing processes.  While, final temperature refers to Post-Process temperature of the finished food products before they are cooled or frozen or stored.  Final temperature after thermal process is very important to prevent Microbial re-growth.

How to Validate a Thermal Process?

There are many different type of Thermal Processing Method such as Retorting (Sterilization), Pasteurizers, Hot-Fill-Hold Processing Method, UHT-Aseptic Process, Soud-Vide Process (Cook-Chill), Freezing (IQF, Blast Freezing, Ethanol Freezing) etc.  

Heat Distribution Test (HDT) and Heat Penetration Test (HPT) are generally used to validate the above thermal processing.    Both test results are essential validation requirement for compliance to FDA/USDA authorities and EU authorities as well.   These tests are very important to ensure that your thermal processing method achieve a fast and even temperature distribution, securing uniform treatment of all containers, without risking neither under- nor overheating.  The HDT and HPT have to be performed frequently as conditions of your system may change during used.  The thermal processing parts like valve, pump, nozzle and etc. have to be repaired or replaced periodically.

HDT and HPT

Heat Distribution Test (HDT) is a series of temperature measurements at different locations inside a retort or cooker, to assess the temperature uniformity and stability through the system. The main objective of HDT is to to find the ”cold spot” in the process machinery, to securing all areas of the process machinery receive the heat scheduled. After an initial test run, at least two replications are recommended for each HDT.  If variations found between these two, the 3rd run is recommended.  The process machinery must be mapped yearly, with every new product configuration or by every modification of the machinery. For new retort, it must be mapped empty and fully loaded.  Beside the above, HDT also used to establish and verify the process schedule which including the Air Evacuation/venting time, CUT time, Equilibration time, Cook/Sterilization HOLD time & the cooling time as well.

Heat Penetration Test (HPT) is to determine the heating and cooling behaviour of a product/package combination in a specific retort system for the establishment of safe thermal processes and evaluating process deviations.  The study must be designed to adequately and accurately examine all critical factors associated with the product, package and process which affect heating rates. 

Before commencing a heat-penetration test, the user should already obtain the result from the Heat Distribution Test (HDT).  The main objective of HPT is to determine the slowest heating point of the container and a heating curve is plot to determine the lethality of the heating process.  

Several product, process, package and measurement-related factors can contribute to variations in the time-temperature data gathered during a Heat Penetration Test. Establishment of a process required expert judgement and sound experimental data for determining which factors are critical and the effect of changing those factors both within and beyond established critical limits. 

Quantitative data on variability should be recorded where appropriate and all pertinent data should be documented to better understand and account for possible variations in Heat Penetration behaviour.

Team Medical Scientific Sdn. Bhd. provides both HDT & HPT to our customers.
Please contact Vivian (vivian@tms-lab.com) for more information.  
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