Frequenty Asked Questions

Stock America - Your Retort Start-Up Experts

What does Retort or Retorting mean?

Sometimes also called an Autoclave or Sterilizer, a Retort is a pressure vessel used in the food manufacturing industry to “commercially sterilize” food after it has been placed into its container and the container has been hermetically

Why would I need to use a Retort for my product?

Retorted products provide consumers with an ambient shelf stable life versus fresh, refrigerated, or frozen products. Products that have a pH greater than 4.6 are considered low acid foods and require a validated retort process to be considered shelf stable.

How does a Retort create shelf stable products?

Containers are filled with product, hermetically sealed, and placed in the retort to be heated to a pre-determined temperature. The temperature is held for a period of time to achieve the desired lethality that ensures the product is safe to consume. The product is then cooled down to a pre-determined temperature and then removed from the Retort to be packaged for sale.

How big is a Retort and how many containers does it hold?

Retorts come in many diameters and lengths dependent on available space and line speed requirements. The products are loaded into baskets and put into the retorts ranging from 1100mm to 1800mm in diameter with lengths ranging from 4 feet to 40 feet depending on how many basket positions per retort.

Are there guidelines I need to follow to process low acid food?

Low-acid foods packaged in hermetically sealed containers in the U.S. are under the jurisdiction of FDA and USDA regulations (Title 21, Code of Federal Regulations (21 CFR) part 113). There are multiple regulations and procedures required to legally sell shelf stable products in the U.S. market. Companies such as Stock America design their retort equipment to meet or exceed all FDA/USDA regulations and can offer guidance to ensure that all regulations are met.

How long does the product need to be heated and at what temperature?

The temperature settings and how long the product needs to be cooked is dependent on many variables including the initial temperature of the product before retorting, the viscosity of the product, the headspace after the product is filled, the texture required by the finished product. A very common temperature widely used is 250 degrees Fahrenheit. The determination of the length of the cook and the temperature is determined through heat penetration and heat distribution testing provided by a process authority. Stock America can facilitate and supervising this testing.

How many Retorts would I need to get started?

This calculation starts with the line speed of the filler, the geometry of the container or containers to be retorted and an estimate of the retort cycle time (total time to load, cook, and unload the product). Once these factors are determined, a capacity analysis is created and the diameter and number of baskets per retort is calculated. Each basket holds hundreds or even thousands of containers depending on the retort diameter and container size. Stock America will run this analysis to assist in estimating the most efficient retort size.

How do the baskets get loaded with product and get in and out of the Retort?

The “Retort Room” equipment starts after the filler/seamer. Raw (or semi raw) products are introduced to a product “Loader” so that containers can be organized in baskets or trays efficiently. Each basket payload range is between 1,000-3,500 lbs. depending on the retort diameter. The baskets are then loaded into the retort in a semi-auto manner using operators, or a fully Automated Retort Delivery System that is fed via conveyors coming from the Loader. Once the Retort is at full capacity, the Retort door is closed and locked and the operator initiates the Retort thermal process. Once the process is complete, the baskets of cooked product are unloaded from the Retort and delivered to the “Unloader”. The Unloader removes the products from the baskets or trays and then conveys them to the end of line packaging area. Each batch of product will take anywhere from 30-90 minutes for a full cycle depending on the product.

What would be my initial investment cost to consider Retorting?

Retort pricing has a very wide range dependent on many factors. If the customer has some basic idea of type of product, type of container, and line speed, Stock America can run a quick analysis and determine the size and type of retort along with how many are required in order to provide a ballpark estimate.

What are some advantages of Batch Retorting versus other technologies?

Batch retorting is by far the best entry level approach because it is the least expensive capital investment compared to Aseptic, Continuous, or Microwave processing; retorting offers unlimited flexibility of containers to be processed versus narrow ranges of other technologies; retorting requires the simplest level of technical training and operation; and Retorting is a very mature technology and therefore very averse to food safety risks.

Do I need special containers for Retorting?

Many container manufacturers offer retortable containers for cans, pouches, glass jars, tubs, cups, plastic bottles, and paperboard boxes in many different geometries. These containers have been tested to handle the harsh retort environment. If the containers are not retort friendly, they cannot be used.

Does my current refrigerated product need to be modified for Retort processing:

While this answer varies dependent on the product, the formulation will likely need changes because of the heat effect on the product. Some ingredients may need to be changed to enhance their heat stability and some aspects of the product texture and taste may change based on the thermal process. Stock America has a test pilot plant on site and access to food scientists to assist with formulations.

How would I test my product before investing in a Retort operation?

There are facilities and universities with pilot plants dedicated to product and process development. Some Retort manufacturers also offer pilot plant development services to help the entry level customers. Stock America has this capability to assist customers trying to enter the market.

How long does it take to start a Retort Operation?

Retort deliveries typically take 6-8 months to deliver to a customer. Once delivered, the utilities are hooked-up, the retort is tested, heat distribution and heat penetration studies are conducted, the thermal process is filed, and then the processor can begin producing product for sale. Once the retorts are delivered, the start-up will last approximately 4-6 weeks to complete all tasks. Stock America offers a turnkey service from order to release of product for commercial sale.

Are Co-Packers available to provide shelf stable Retorted products?

Co-Packing is a good way to run product at a 3rd party facility as a step to test the market viability for a given product prior to making a permanent capital investment. There are multiple co-packers in the U.S. and the plants will specialize in a given market segment such as beverage, ready meals, pet food, soups, sauces, etc. Finding a co-packer to partner with is becoming more challenging in recent years due to the number of craft processors in the market and the shift of large CPG Companies that now use co-packers versus processing in-house.

How many employees does it take to operate a Retort installation including the Material Handling?

Most entry level processors will begin by investing in a semi-automatic operation in order to minimize their initial capital investment. In these cases, the Retort Room operation would need approximately 5-7 employees. If the Retort Room is totally automated, only 1-2 employees are required. A good strategy is to layout the Retort Room for a fully automated system so that you can make an easy transition from a semi-auto operation to an automated factory once the business grows. Stock America has a full line of material handling products from semi-auto to fully automated options to support entry level processors on all levels