When facing the stage of fitting a line in a given production area, arranging the retorts in the room is almost always a challenge. The common result is compressing everything to very limited space and underestimating the negative impact that this can have on the final quality of the product.

To make this explanation simpler, let us focus on metal cans, with which there is the possibility of loading them compactly, or even scrambled in baskets. In general, the risk of damage of such containers is not as great as with containers made of other flexible materials.

Scrambled loading of cans in retort baskets

“Convenience” packaging but less robust

A few decades ago, tin plate cans were made of thicker steel sheets than today and without easy-open ends (EOE). These containers were more tolerant to bumps during the loading of the retort baskets and were also able to be processed at low-pressure using saturated steam. Although the aluminum can with an easy-opening end has gained an enormous presence in the market, we can still find traditional thick tin plate cans around. On the other hand, the use of saturated steam retorts for these cans has become a limitation to technological progress.

Higher pressure sterilization processes

The use of less expensive cans (with thinner walls), in line with competitiveness and environmental sustainability, requires retorts with air overpressure process technology to raise the pressure in the chamber to a level such that the weaker cans can resist the internal temperature generated at high temperature without deformation.

Air itself is a low-conductive media and using it to compensate for the internal pressure in the can worsens the heat transfer in comparison to the saturated steam retort. Therefore, this scenario poses a dilemma that confronts critical variables in the industry such as capacity, cost-saving, and quality.

Saturated steam technology requires more energy than modern steam-air or steam-water technologies but reduces heating time and improves temperature distribution by previously pushing out all air in the chamber (venting phase).

The capacity, cost-saving, and quality ratio face the dilemma of footprint. The evolution of the market trends leads the industry towards new packaging materials and formats, for which the variable capacity is negatively affected by the need to use compressed air.

Quality versus capacity

While pursuing a homogeneous heat treatment when using compressed air to get the correct counterpressure inside the retort, the key to the success is to load the cans in a way they are not compactly layered or scrambled. Not only for the container integrity itself but also for ensuring that the content has been correctly treated.

Compact loads make it difficult to have efficient and homogeneous heat transference to each can’s core, especially to those located away from the outer positions in the baskets or from the heat source. The result is a temperature difference between the cans so high that some may be overcooked or, wore, understerilized. The industry usually takes the overcook option, prioritizing food safety over the organoleptic properties of the product.

The answer to this dilemma is clear: loading methods that promote heat transfer and protect the integrity of the container is the way to offer products of high quality in modern packaging.

Automatic handling systems, the solution

Automated handling systems are the answer to achieving the ultimate balance between footprint, production capacity, and quality. Nowadays, the great development of robotic systems and the smart engineering of handling systems allow a production rate per square meter that was unthinkable just a few years ago.

Automatic retort loading of trays with plastic cups

At Surdry we encourage our clients to explore together with us the solutions best adapted to modern times where quality can be matched with efficiency and the best use of the footprint and the energy.

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