Sterilizing a food product in a retort is intended to stop microbial growth for a period of time. But as a thermal process, it also cooks the product and this is why the design of the retort recipe is key to obtain the best quality. You may want to reduce the cooking effect as much as possible and keep texture and color as close as possible to the unsterilized products. Alternatively, you may want to design the recipe to take advantage of the thermal process to cook the product at the same time. You may even fill dry products and design the sterilization recipe to cook and sterilize with the same thermal process. Interesting, isn’t it?
Here are some critical factors you must consider so as to design a good recipe:
Dwell time: How much can your product wait to start sterilization after packaging?. Long waiting may cause microbial growth, hot fill cooling, and bad initial temperature differential in the retort batch.
Heating ramp: Short to reduce the cooking effect or slow in accordance with your cooking goals?. Convective or conductive heat transfer will make a difference.
Sterilization temperature: High-temperature short time is best to reduce the cooking effect, but it may not be best for the product you want. Same as with quick heating, a high temperature very likely will cause scorching on the surface of solid or viscous products.
Process pressure: Package integrity is also a key element associated with food safety. If the retort pressure profile is not well balanced to the pressure profile inside the package, this will only rely on its robustness to keep hermetically sealed during the retort process.
Level of agitation: Very often the product agitation provides so little benefit that the cost of agitating does not pay. However, there are many other products, particularly those where agitation will force convection heating, for which the choice of a gentle swing or a full rotation is again a key factor that must be carefully tested.
At Surdry you will find the expertise to help you with the best retort recipe and the necessary equipment to take you from the lab test to the production line.
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