Basic Information on Thermal Processing


Presentation Abstracts for the

Thermal Processing of Ready-to-Eat

Meat Products Short Course

Sanitary Facility Design

The first principle of sanitary design is that the facility be cleanable to a microbiological level.  The three broad themes involved in designing a sanitary food processing plant environment are providing zones of control, keeping the environment cold and controlling moisture, and arranging equipment in order to facilitate sanitation efforts. The 11 Principles of Sanitary Facility Design were developed to assist meat and poultry processors in identifying fundamental control strategies for achieving specific objectives within these three themes."

The overall goal of sanitary facility design is to create a controllable environment. The drier the facility, the easier it is to control microbial growth.  This means building a solid foundation of GMPs, sanitary equipment and facility design principles and HACCP programs, upon which the company can enhance employee-training efforts and thus improve verification and validation of processes.  In terms of sanitary facility design, planning for success means taking the "as-is" model of the facility and comparing it to the processor’s "want-to-be" model to get an accurate view of how the company can adjust to enhance both its food safety and efficiency goals.  A five-step process, beginning with a facility design audit (using a checklist like AMI’s) customized for the processor’s specific application and desired facility model, is a good way to bring the food safety plan into the company’s master corporate plan.

Food safety is, indeed, the most important issue any food company faces year-in, year-out. Its importance to public health, coupled with the potentially devastating consequences of a breakdown somewhere in the food safety web, have driven industry associations, sanitation and safety experts, and watchdog organizations to establish guidelines not only for food handling, but for plant and process line design. Adhering to these recommendations can dramatically reduce the possibility of a devastating food safety event.  Factors, such as traffic and air flow, temperature, moisture, nutrients, pH, and competing organisms must factor into sanitary design planning.


Sanitary Equipment Design

Food safety hazards generally can be categorized as microbiological, chemical or physical. Most of the principles of safety revolve around the avoidance of entry, harborage or build-up in the facility ... of anything that doesn't belong, be it microbiological hazards, insects, rodents, plain old dirt, even unauthorized personnel. This principle is especially important at the points in the process where the product that will be ultimately consumed is most vulnerable.

It is critically important to remove all food particles, and to prevent bacterial ingress, survival, growth and reproduction on both product and non-product contact surfaces.  Essential to the concept of a sanitary design is thorough cleanability. That means a facility in which you can clean out and eliminate not only debris and chemical substances but tiny microbial invaders as well.   Food facilities and equipment must be constructed--and able to be maintained--to ensure that they can be effectively cleaned and sanitized over their life.

Any piece of the food safety puzzle must be viewed as only a part of the total picture.  Any complete food safety program should integrate employee programs, validated and verified processes, good manufacturing practices, sanitary equipment design, analyses of critical control points and continuous improvement processes as well as sanitary facility design.


Microbiology of Cooked Meats  

The quality of ready-to-eat (RTE) meat products and the success of meat companies depends largely on the microbial quality of the raw materials, the cooking process, preventing post-cook contamination, and effective control of microbial growth in the finished product.  Therefore, an understanding of the sources of microorganisms that contaminate both fresh and cooked meats, as well as the factors that affect microbial growth, is very important to meat processors if they are to produce safe, high quality, desirable meat products for consumers.


Equipment and Process Validation for Batch and Continuous Ovens

There are several oven variables, which affect the cooking of meat products, such as cooking time, temperature, relative humidity and air velocity. These variables apply to both batch and continuous ovens. Sources of temperature variation can be oven design, product loading, product shape and the cooking process. Balancing an oven is dependent upon airflow and air handling. Methods for balancing ovens and preventive maintenance checks are discussed. Equipment validation issues, which are presented include: frequency of validation, location and number of probe(s), temperature measurement equipment, and time limits for actually taken product temperature.


Thermal Processing of Slurries with Indirect Heating Systems                        

Cooking viscous products such as ground meat or products with diced meat and vegetables in a thick, spicy sauce in a vessel with a heated jacket is completely different from cooking non-viscous, homogeneous liquids.  The heat transfer principles are altered due to more difficult mixing of the product and the problem of the product sticking and cooking to the heat transfer surfaces.  This section with discuss heat transfer in general in this environment as well as practical techniques for cooking products with proteins, spices, sugar and dairy products ingredients.  The different techniques of heating (steam, hot water, thermal oil) in the heat exchange jacket will also be discussed as well as methods and considerations of cooling slurries.


Data Logging and Tracking

The use of hand held thermometers for confirmation of cook / chill CCPs for HACCP compliance is now wide spread in the ready to eat meat market. Spot check temperature measurements post process, although invaluable in proving food safety, give little more information to help validate or optimize the cook / chill process.

This presentation aims, therefore, to introduce the concept of in-process temperature profiling to complement basic product temperature spot check procedures. The use of multi-channel data logging systems to monitor both product and environmental temperatures in process are discussed. Processes highlighted include batch cook and chill, conveyorized linear/spiral ovens and freezers and also in line fryers.

The use of collected profile temperature to optimize and validate processes as part of the HACCP procedure will be reviewed but also the use of such data as part of any necessary HACCP corrective action plan. Use of profile data to improve product quality and yield along with process efficiency will also be discussed.

The implementation of temperature profile for variety of processes will be covered detailing technical challenges and developments to overcome them including thermocouple design and use, real time RF data acquisition in batch and conveyorized processes, custom food tray use for quick, easy and repeatable measurement and new advanced data analysis and reporting capabilities.


Temperature Measurement

The variables of temperature measurement include: the design of the sensors (dial vs. digital), the effects of the oven design (batch or continuous) on hot and cold spots and temperature monitoring, and appropriate sensors and measuring procedures for different shaped and sized meat products. Proper procedures for end point temperature checks, real time tracking for F-value calculation in order to validate cooking processes, are also discussed.


Processing Interventions to Prevent L. monocytogenes Growth

There are a variety of processing interventions available for preventing the growth of L. monocytogenes in RTE meat products.  This presentation summarizes the advantages and disadvantages of the interventions that are currently commercially available and introduces emerging intervention technology that will hopefully be commercially available in the near future.


Fundamentals of Continuous Thermal Processing

We will discuss and define what constitutes a continuous thermal process (cooking), which is followed by a brief description of common cooking equipment used in continuous thermal processing.  We will then review the three basic types of heat transfer as they relate to all continuous thermal processing.  The final portion of the presentation will cover defining the basic variables common to all continuous thermal processing lines.  In summary we will discuss how those variables interact with environmental conditions, equipment types, and types of product.


Mechanics of Chilling RTE Meat Products

The chilling process of meat products is a physical process, dependent upon the thermal properties of the product as well as the chilling medium, the size and shape of the product, and the temperature difference between the product and the chilling medium. Material handling methods can also affect the chilling process, such as how the product is loaded upon trees, whether the process is continuous or batch, and whether the product is showered or submerged. The brine solution can affect to chilling efficiency, depending upon the differential temperature between the product and the brine, brine coverage of product and whether the product is showered or submerged.


Post-Packaging Pasteurization of Cooked Meat Products

Surface pasteurization has become a very important process for destroying vegetative pathogens, which could make contact with exposed meat products between cooking and packaging. While there are pasteurization regulations for other food products, there are currently no regulations for surface pasteurization of cooked meat products. The process needs to be established for each product, based upon the desired level of destruction at the product surface. Factors, which complicate this process are the shape, uniformity of the product surface, and the size of the products, as well as the package configuration. Equipment for both batch and continuous surface pasteurization are discussed.


Third Party Audits

The importance of third party audits, as multi-faceted evaluations, covering all aspects that

directly or indirectly affect safety of RTE meat products, is discussed.  This presentation presents

means to independently determine that an appropriately designed control system exists and that it

is being operated under control.


Documentation Materials for HACCP Decisions       

This Supporting Documentation Materials for Hazard Decisions was developed to assist meat and poultry processor, in the scientific documentation of their HACCP decisions during hazard analysis, validation of plans, and corrective actions, by compiling food safety-related data and guidelines from scientific publications and regulatory documents. Organized by HACCP process category, this material was designed to assist establishments after their specific hazards of their process(es) have been identified. In the original document, it was assumed that not all possible hazards were addressed, and that many steps that were included in this information may not necessarily be hazards in a particular establishment’s process. This material includes USDA FSIS and FDA regulations, as well as published scientific research. The research that has been done does not necessarily comply with current regulations, nor are all of the parameters a part of normal processing conditions. Some of the treatments discussed are not within the legal limits; other treatments may not be approved at any level. Some of the research in this manual shows that certain conditions are not effective in reducing or eliminating risk; other conditions may create a probable risk. This information is presented not only to validate existing processes, but also to demonstrate the effectiveness, or lack thereof, of processing steps that may be added to an establishment’s process in the future. Where available, a website is given to allow direct internet access to publications.


Heat & Mass Transfer

This presentation provides a layperson’s introduction to the underlying physical principles that govern all cooking processes, and which therefore are critical to the safe production of ready-to-eat meat products.  Objectives are to describe the various mechanisms of heat and mass transfer, to explain the differences between steady-state and unsteady-state transfer, and to describe some basic methods for estimating heat or mass flow.


Lethality Treatment Determination: Calculating Thermal Inactivation of Pathogens

The application of integrated lethality calculations using actual product temperature data to determine the effectiveness of a heating process is described.  The advantages and limitations of existing tools are discussed. 


Food Safety Beyond Guidelines and Regulations

Growth in the ready-to-eat (RTE) market sector and evolving federal regulations are creating a need for better information related to inactivation and growth of pathogens in meat and poultry products. Regulatory changes are shifting the burden to processors to ensure, through scientific rationale, that a new or modified process meets lethality and stabilization performance standards. Although product and process parameters are known to affect thermal resistance of bacteria, most reported information is from laboratory studies that encompass a limited range of conditions. In most cases, the validity of this information for commercial processes is uncertain. Therefore, the purpose of this presentation is to address three questions: (1) how does the scientific domain of the performance standards for RTE products relate to the current state-of-knowledge, (2) what is currently known about various factors that might affect thermal inactivation of pathogens in meat and poultry products, and (3) what should be done to account for these complicating factors, now and in the future.