Sterilization in plastic trays
Everything you need to know about sterilization of food packaged in plastic trays
In this section you will discover the particularities of pasteurizing or sterilizing any food packaged in a plastic tray, also known as punnets. You will also learn the pros and cons of packaging your product in this type of container.
Trays for preserves and ready meals
A tray, as defined in dictionaries, is a sturdy yet lightweight receptacle commonly used for storing and preserving food items.
In the food industry, especially in the canned food and ready meals sector, trays of different materials, sizes and depths can be found. These containers tend to be made of polypropylene plastic (PP) of different colors, and are capable of being heat-sealed, with options for inclusion of a lid or not.
The journey of plastic trays, specifically designed for canned goods and convenience foods, has been significant since their inception in the food sector. Historically, food packaging predominantly involved the use of glass or metal containers, which, despite their effectiveness, had drawbacks such as heaviness and breakability.
With the advent of plastics in the 20th century, plastic trays became a revolutionary alternative due to their lightness, strength and versatility. In particular, polypropylene (PP) stood out for its ability to withstand high temperatures, , rendering it suitable for food sterilization processes like autoclaving. This method is crucial for enhancing the safety and longevity of food items, all while maintaining the food’s inherent qualities.
Such advancements have facilitated improved efficiency in distribution and storage logistics, paving new avenues for the canned goods and prepared meals sectors.
Types of trays for food
Various tray designs are available for food packaging, including single-serve, family-sized, and shapes like rectangular, round, and even octagonal.
As previously noted, it’s crucial for these trays to be capable of heat-sealing. For this purpose, oriented polypropylene (OPP) film is used, which is a type of plastic that can endure the autoclave’s intense heat.
The method used to seal trays is by pressure and heat.
In scenarios involving the production of gourmet preserves or convenience meals on a small to medium scale, the sealing operation tends to be executed manually or with semi-automatic machinery, differing mainly in their level of automation.
Advantages and disadvantages of plastic trays for the production of preserves and ready meals
Trays or semi-rigid trays are increasingly used in the production of gourmet canned foods and ready-made meals, especially in the case of pre-cooked food.
Trays are containers that allow you to see the products they contain and can be heated in a microwave oven or even be frozen. In addition, they are quite economical containers, both in terms of production and distribution, as they are lightweight and easily stackable, which saves energy in transportation.
Another advantage over glass containers is that since they do not close with a screw cap or twist off caps, it is not necessary to leave an empty space at the top.
On the other hand, and as a disadvantage, it is worth mentioning the material used to manufacture them, which has a high impact on the environment. Although polypropylene is recyclable, it is still a plastic, therefore, it is made from fossil fuels and takes many years to decompose.
In addition, and also as a disadvantage, we can point out the need to change the food from one container to another once it has been opened. Unlike the glass container, which can be closed again to protect the product, the tray is thermosealed, and if it does not have a hard lid, once the seal is broken, it cannot be closed again.
You may have heard or read that plastic is more porous than glass and the chemicals it contains can end up in the food. But you must know that this belief is not true. To avoid this possibility, various migration tests are usually carried out, which consist of ensuring that no chemical component of a container can be transferred to the packaged food inside it. Those containers that do not pass these migration tests are considered unsuitable for food use, therefore, they are not marketed.
If you still don’t know which type of container is best for your gourmet preserves or ready meals, take a look at this article and find out which are the most appropriate containers for the production of preserved food.
Preserves and ready meals in plastic trays
Typically, dishes that come in trays are precooked and designed for convenience, requiring only heating before consumption. This category includes a variety of meals like pasta dishes, meatballs in sauce, various soups and creams, lasagna, paella, fideuà, and stews with chicken or vegetables.
These meals are commonly stored in refrigeration units and tend to have a limited shelf life. The reason behind this is their preparation method; they are pasteurized to preserve their taste, aroma, texture, and overall quality for as long as possible.
While you might encounter some of these meal trays stored at ambient temperatures, those instances are less common and typically indicate that the food has been subjected to sterilization, a more intensive preservation process than pasteurization.
How to produce preserves and ready meals in plastic trays
Before embarking on the creation of your gourmet preserves or pre-cooked meals in plastic trays, start by ensuring that you have enough of them and that they are in perfect condition. Remember that it is always advisable to sanitize them beforehand.
Keep in mind that not all plastic materials are suitable for pasteurizing or sterilizing food by autoclaving. Verify the compatibility of your trays with such processes by reviewing their specifications and consulting the manufacturer if necessary.
Once these preliminary steps have been completed, you can start cooking your food. It is better not to cook it at all because the autoclave will finish the cooking process. Click here to learn more tips on how to avoid smell, taste, color and texture changes in your gourmet preserves and/or ready-made meals.
Next, fill the trays with your culinary creations and proceed with thermosealing. Following this, the trays are ready for pasteurization or sterilization.
Once the heat treatment has been completed, if you wish, you can protect the heat-sealed film with a hard cover to avoid possible cracks, thereby increasing the container’s durability.
Useful tips for sterilization in plastic trays
During the thermal expansion of the samples in the sterilization phase and during the cooling phase, the containers may break or spill, due to the expansion and contraction of air contained inside the trays. Therefore, if a tray is nearly full and does not contain excess air, fewer problems will arise.
n parallel and in order to prevent this from happening, TERRA Food-Tech® autoclaves have an integrated air compressor that automatically supplies additional pressure in an intelligent way. For this reason, counterpressure plays an important role in the outcome of the container characteristics.
In the specific case of plastic trays, we recommend the use of programs with multiple ramps. The segments can be programmed by time, pressure and temperature. These segments can be included before or after the sterilization phase.
How do TERRA Food-Tech® autoclaves enhance the sterilization process for your plastic trays?
The different characteristics of TERRA Food-Tech® autoclaves for sterilizing trays 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 our autoclaves.
More and more local producers, farmers and chefs are using our autoclaves to produce their own canned foods and ready-made meals. Visit our success stories section and get inspired to start your own canned food business.
Explore additional articles on sterilization across various types of containers.
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