Thermal processing of food

Thermal technologies have been at the core of food preservation and production for many years. It involves heating foods in hermetically sealed containers for specific time at a specific temperature to eliminate the microbial pathogens that endanger public health and microorganisms and enzymes that deteriorate food during storage.

Ever since the invention of thermal processing as a method of preserving packaged foods by the Frenchman Nicolas Appert in the early 19th century, there has been a relentless search to reduce the amount of thermal damage to the quality of food products.

Today, however, the consumer demands much more than just safe and shelf stable food, including, primarily, higher quality food with greater convenience in the end use.

And food processors look for more energy-efficient, cost effective and high-speed processing technologies. Numerous methods exist for thermal processing of foods. Some of these techniques include the use of steam injection, stem infusion, tubular heat exchangers, shell and tube heat exchangers, plate heat exchangers, scraped surface heat exchangers extruders, ohmic heaters, infrared heaters, radio frequency heaters, microwave heaters and variations, combinations of these.

High temperature, short-time (HTST) techniques have primarily involved to minimize the severity of heat treatment and promote product quality.

Whatever the material and its shape or the food product it is necessary to apply a suitable process, i.e. given time at a specified temperature, to ensure that the products do not pose a public health problem, e.g. food poisoning.

Continuous aseptic processing, also called continues flow processing  and packing further minimize the heat severity by quick heating and cooling of the food, prior to packaging, under aseptic conditions.

Product must be heated to a set temperature for a set time in order to achieve a commercially sterile product.

This profile, thermostable, microwavable packages have been developed for promoting faster heat transfer rates, which minimizes the heat damage to product quality while adding the convenience of package microwavability.

Rotary and continuous cooker for canned food have been based on product agitation during processing to accelerate the rate of heat transfer in order to promote better quality in processed foods.
Thermal processing of food

Heating in food processing

Heating is one of the most essential methods for food preservation mechanism that applied by the food processor to render food products commercial sterile – that is free from pathogenic and spoilage microorganisms likely to grow during the normal distribution and shelf-life of the product.

Conventional heating methods sue external heat sources including hot water and steam. Heat may be transferred by one or more of the three mechanisms of conduction, convection and radiation.

Most industrial heat transfer operations involve a combination of these but it is often the case that one mechanism is dominant.

Heat sterilization of food in containers is an old technology largely attributed to the work of Nicholas’s Appert in the 1800s.

As introduced and developed in the initial stages, the primary focus of canning was safety and shelf stability. The application of heat processes to containers requires not only the ability to heat and cool the container contents efficiently but also the ability to do so while minimizing the stresses imposed upon the container.

Whether electrical or conventional, heating may be broadly classified as unit operations in blanching, cooking, drying, pasteurization, sterilization and thawing and involve raising the product to some final temperature that depends on the particular objective of the process.
Heating in food processing