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The Basics: Retorts

Updated: Apr 30

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Retorting is a very effective and popular way to create shelf-stable products. Let's take a look at what it is, the different types, and what type of packaging is used.


Retorting is a method of food preservation that involves heating packaged food products to high temperatures to achieve sterilization. It is commonly used for preserving shelf-stable canned foods, such as vegetables, meats, seafood, soups, and ready-to-eat meals.

Here's how the retorting process typically works:

1. Packaging: The food product is first placed into a sealed container, such as a metal can, glass jar, or flexible pouch. The packaging must be able to withstand high temperatures and pressure without compromising its integrity.

2. Heat Treatment: The packaged food is then placed into a retort, which is a large pressure vessel capable of withstanding high temperatures and pressures. The retort is filled with water, and steam is used to raise the temperature inside the vessel.

3. Heating: The temperature of the water and steam is gradually increased until it reaches the desired sterilization temperature, typically between 115°C to 121°C (239°F to 250°F). The food is held at this temperature for a predetermined period, usually ranging from several minutes to over an hour, depending on the product and packaging size.

4. Cooling: After the heating period is complete, the pressure inside the retort is slowly released, and the temperature is gradually reduced. This rapid cooling helps to minimize overcooking of the food and prevents spoilage.

5. Packaging Inspection: Once the retorting process is finished, the packaged food is removed from the retort and allowed to cool to room temperature. The packages are then inspected for proper sealing and any signs of damage or contamination.


Retorting is an effective method of food preservation as it destroys harmful microorganisms, such as bacteria, yeasts, and molds, that can cause spoilage and foodborne illness. The high temperatures used during retorting also help to denature enzymes and extend the shelf life of the food product. Additionally, retorted foods do not require refrigeration, making them convenient for storage and distribution.


However, it's important to note that the high temperatures and pressures involved in the retorting process can affect the texture, flavor, and nutritional content of the food. Therefore, retorted foods may not always retain the same sensory qualities as fresh or minimally processed foods.


Moving onto the types of retorts used, there are several for discussion. There are several types of retorts used in food processing, each with its own design, configuration, and applications. Here are some common types of retorts:


1. Water Immersion Retort: In this type of retort, packaged food products are submerged in water inside the retort vessel. Steam is injected into the water to heat it, and the heat is transferred to the food through conduction. Water immersion retorts are versatile and can accommodate a wide range of container sizes and shapes.

2. Steam Spray Retort: Steam spray retorts use a combination of steam and water spray to heat and sterilize the food products. Steam is injected directly into the retort vessel, while water sprays help to distribute heat evenly and maintain a consistent temperature throughout the retort. This type of retort is often used for processing large batches of canned foods.

3. Static Retort: Static retorts are stationary vessels with fixed shelves or baskets where packaged food products are loaded. Steam is introduced into the retort vessel to heat the products, and the vessel is sealed to maintain pressure during the sterilization process. Static retorts are commonly used for processing canned foods, pouches, and glass jars.

4. Rotary Retort: Rotary retorts consist of a rotating drum or vessel that moves the packaged food products through various stages of the retorting process. The rotation helps to ensure uniform heating and sterilization of the products. Rotary retorts are often used for high-volume production of canned foods and pouches.

5. Continuous Retort: Continuous retorts are designed for continuous processing of food products on a conveyor belt or through a series of chambers. The products move through the retort at a constant rate, undergoing heating, sterilization, and cooling stages. Continuous retorts are suitable for high-speed production lines and can handle a wide range of container sizes and shapes.

6. Hydrostatic Retort: Hydrostatic retorts use water pressure to achieve uniform heat distribution and sterilization of packaged food products. The retort vessel is filled with water, and steam is injected to increase the temperature and pressure inside the vessel. Hydrostatic retorts are often used to process large containers and flexible pouches.


Each type of retort has its advantages and is chosen based on factors such as the type of food product, production volume, packaging format, and processing requirements. The selection of the appropriate retort is crucial for ensuring efficient and effective sterilization while maintaining the quality and safety of processed foods.


A wide range of food products can be retorted to achieve shelf stability and ensure food safety. Some common types of foods that are retorted include:

1. Canned Vegetables: Vegetables such as corn, peas, green beans, carrots, and potatoes are often retorted to preserve their flavor, texture, and nutritional value.

2. Canned Soups and Stews: Various types of soups, stews, and broth-based products are retorted to ensure microbial safety and extend shelf life.

3. Canned Meats and Seafood: Meats such as chicken, beef, pork, and seafood like tuna, salmon, and shrimp are frequently retorted to create shelf-stable products.

4. Ready-to-Eat Meals: Complete meals, including combinations of proteins, grains, and vegetables, are retorted to provide convenient, shelf-stable options for consumers.

5. Sauces and Condiments: Sauces, gravies, marinades, and condiments like salsa and pasta sauce are retorted to ensure food safety and extend shelf life.

6. Pet Foods: Some types of pet foods, including wet foods and treats, are retorted to provide convenience and ensure product safety.


When looking for a copacker for retorted food products, several potential issues may arise:

1. Equipment and Capacity: Not all copackers may have the necessary retorting equipment or sufficient capacity to handle large volumes of retorted products. It's essential to find a copacker with the right equipment and production capabilities to meet your needs.

2. Quality and Food Safety Standards: Retorting is a critical step in ensuring food safety, and it's crucial to work with a copacker that adheres to strict quality and food safety standards. Look for copackers with certifications such as HACCP (Hazard Analysis and Critical Control Points) and SQF (Safe Quality Food) certifications.

3. Packaging Compatibility: Retorted foods are typically packaged in containers such as metal cans, glass jars, or flexible pouches. Ensure that the copacker has experience working with your chosen packaging materials and can provide appropriate packaging solutions for your products.

4. Regulatory Compliance: Copackers must comply with regulatory requirements governing food processing, labeling, and safety. Ensure that the copacker is knowledgeable about regulatory standards and can assist with compliance issues.

5. Communication and Collaboration: Effective communication and collaboration are essential for a successful partnership with a copacker. Clearly communicate your product requirements, expectations, and timelines, and ensure that the copacker can provide the level of support and responsiveness you need.


By addressing these potential issues and conducting thorough research and due diligence, you can find a copacker that meets your needs and helps you bring your retorted food products to market successfully.


As always, happy hunting!


The CVL Team

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