Sterilization in cans
Everything you need to know about sterilization of food packaged in cans
You have probably seen on the shelves of your supermarket a wide variety of preserves packaged in cans. In past times, cans were a great innovation that still persists today. In this article we will tell you the history of this metal container and then focus on its characteristics when it comes to pasteurizing or sterilizing them.
The origin of canned food
First of all, let’s take a brief overview about the history of this type of metal container used to preserve foodstuffs.
It all started with Nicolas Appert, a French pastry chef-confectioner who, at the end of the 18th century, devised a simple method of preservation. If you want to know more about it, you can find out all the details in our article about the History of Canned Food.
Fast forward to 1810, when Philippe de Girard, a French engineer and inventor, based on Appert’s discoveries, decided to replace glass jars with tin containers. He partnered with an English businessman named Peter Durand, who patented the tin can. This patent was sold to Bryan Donkin and John Hall, who in 1813 began the commercial manufacture of canned preserves for the British Navy.
At first, those cans were sealed with lead solder, a highly toxic material that wreaked havoc at that time. One of the most famous cases was the Arctic expedition of John Franklin, in which the crew was poisoned after consuming canned food for three years.
The first can opener was invented in the 1850s and more than a century later, in 1963, cans with the easy-opener system were invented.
Today, cans are made from materials that are completely safe for health and can maintain the full flavor and quality of preserved foods for many years.
Types of cans used for food preservation
Cans are containers made of tinplate, which is a sheet of iron or steel, tin-plated on both sides.
In addition to tinplate, TFS (Tin Free Steel), which is chrome-coated steel, is also used for food packaging and is mainly destined to produce lids and bottoms, two-piece cans and crown caps.
Today, aluminum is largely replacing these types of steels. Especially, in trays of precooked foods and terrines for custards or yogurts.
Aluminum is a metallic chemical element, with atomic number 13, which has several industrial applications. It is produced from bauxite, which is an aggregate of various aluminum minerals. Although it is very abundant in the earth’s crust, it is a toxic element, therefore, aluminum containers for food preservation must have an internal coating that prevents any possible migration of this metal into foods.
Cans, irrespective of their material composition, come in a duo or trio of parts: container and lid or bottom plate, body and lid.
And in terms of shape, they can be:
- Round
- Rectangular
- Oval
Advantages and disadvantages of cans for the production of canned food and ready meals
Aluminum is replacing tinplate because it is a lighter and more malleable material. Aluminum can be processed in thinner sheets, which saves costs, both in production and transportation. But in terms of energy, it is a very expensive material to produce.
Both tinplate and aluminum containers withstand the high temperatures of sterilization and remain unaltered over time. Both materials are corrosion resistant and protect from air and light. They also cool quickly because metal is a good thermal conductor.
Another advantage is that these containers can be perfectly recycled and reused, although the aluminum recycling process is simpler because the components do not have to be separated.
As a disadvantage, it should be noted that the content cannot be viewed. And, in the case of aluminum, it can end up affecting the taste of acidic foods.
Did you know that all you need is a magnet to differentiate whether a container is made of steel or aluminum? Tinplate is a magnetic metal while aluminum is not.
If you still don’t know which type of container is best for your gourmet preserves or ready-made meals, take a look at this article and find out which are the most appropriate containers for canned food production.
Canned food and ready meals in cans
The most common gourmet preserves or ready meals that can be found in cans are:
- Olives
- Sauce bases and stir-fries
- Vegetable drinks, such as coconut milk
- Broths
- Vegetable creams
- Sausages
- Pet food
- Fruits in syrup
- Hummus
- Pates
- Ready-made dishes such as meatballs in sauce, vegetable stews, etc.
- Fish and seafood, such as tuna, sardines, etc.
- Dairy products, such as condensed milk
- Whole raw tomato, crushed or stir-fried
These products come in a range of packaging sizes, starting from small 115-gram options to larger quantities exceeding 1 kilogram, accommodating various consumer needs and preferences.
How to produce preserves and ready meals in cans
- You must verify that you have the cans you need with their corresponding lids. Everything must be in perfect condition, with no dents or holes.
- If the cans are not new, they should be cleaned and sterilized.
- Time to start cooking. Remember that it is not advisable to cook your product completely if you are going to use an autoclave, since the heat of the thermal treatment will finish the cooking process.
- Place the preparation in the can using a spoon or tongs. Fill completely without leaving an empty space at the top.
- Close the cans using a sealing machine.
- Pasteurize or sterilize using an autoclave.
- Proceed with labeling, either manually or automatically with a labeling machine.
- Store and/or distribute.
Keep in mind that if you have pasteurized your canned foods, you should keep them refrigerated. If the pH is very low or the sugar concentration is very high, this won’t be necessary, and the pasteurized product can be stored at room temperature.
Should you pasteurize or sterilize your canned foods and ready meals in cans?
In general, gourmet canned foods and ready-made meals packaged in metal containers must be sterilized. For this reason we usually find these products at room temperature and they can have a shelf life of up to 5 years.
However, we can also find cans in refrigerators and this is because the preserves have been pasteurized.
What determines a heat treatment or other process will never be based on the type of container, but on the food, its level of acidity and the purpose of the person who prepares it.
Common problems related to sterilization in cans
One of the biggest problems when pasteurizing or sterilizing preserves packaged in cans is oxidation. To solve this problem, an external coating is applied, consisting of a thin layer of tin; and an internal coating is also used, either tin, baked enamel or both.
In addition, when using an autoclave, it is advisable to place the containers separately from each other and also use silicone separators between them.
In any case, once the can has been opened, it is recommended to transfer its content to a glass or plastic container before storing it in a refrigerator, as the direct contact of metal, food and oxygen can cause rust stains.
Useful tips for pasteurization or sterilization in cans
Although cans do not allow to see their contents, their appearance is still relevant, especially when it comes to opening them. You certainly don’t want to give an unpleasant impression to your customer. Of course, it is also essential to take care of the details on the outside of your containers. Here we insist on the importance of making sure that your cans are not dented, rusted or bruised, because they can lose their sealing properties and allow microorganisms to enter and contaminate the product.
On the other hand, and taking into consideration aspects that are totally harmless to human health, it is possible that the upper part of your product has a darker tone. This is quite normal and can be avoided with a splash of olive oil on the product before sealing and sterilizing.
Do you want to know more ideas to make your preserves look good and avoid organoleptic alterations? Remember that you can follow these tips so that your gourmet canned foods and/or ready-made meals do not have changes in their smell, taste, color and texture.
Back pressure plays a very important role in the final result of your products. In the case of cans, back pressure prevents breakage of containers during processing at maximum temperatures. We recommend that you maintain a constant pressure until the sample reaches a temperature of 100°C.
How do TERRA Food-Tech® autoclaves help you to sterilize your cans in a better way?
The different characteristics of TERRA Food-Tech® autoclaves for sterilizing glass jars make a small equipment a great production partner that is cost-efficient, fast and versatile.
Adjustable F₀ - P₀
Pasteurizes or sterilizes accurately using F₀ and P₀ values
Fast cooling
Fast cooling by water shower to avoid overcooking the product
Adjustable counterpressure
Programmable counterpressure value according to the type of container
Traceability for audits
Manage and record the process from start to finish with our software
Precise control
Continuous process monitoring thanks to the flexible temperature probe
Protection
Excellent safety measures for the user and his products
Are you looking to enhance the production efficiency of your preserves or prepared meals business?
At TERRA Food-Tech®, we assist you in assessing the productivity you can achieve with various models and types of containers.
The insights from these analyses prove invaluable when choosing the most appropriate autoclave model for your project.
Such evaluations remain beneficial even after acquiring an autoclave, as they enable us to understand how production capacity may vary with changes in container size.
Moreover, we design tailor-made baskets and racks to suit the specific requirements of your business.
Need some inspiration? Dive into the success stories of our customers who utilize cans.
Haven’t you seen our success stories yet? In that section you will be able to know the different experiences of our customers using our autoclaves and you will have the opportunity to learn from them as well.
An increasing number of local producers, farmers, restaurateurs and chefs are using our autoclaves to produce their own canned foods and ready meals. We hope that all these stories will inspire you to start your own business.
More information on sterilization in containers
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