Retort pouches as a daily pouch was widely used in our kitchen life. It’s a good assistant for us. For those a thoustand types of retort pouches, do you really know what exactly are retort pouches? Or how’s work for our life? What’s special of the material and how’s the standard of those food packaging?

In this article, we’ll show you the answer! Let’s get to know more!

boiling pouch

Made from heat-resistant laminated plastic, retort pouches are semi-rigid, flexible packages. Food products like soups, pasta, rice, sauces, and cook-in-a-bag meals are sealed and sterilized in these pouches with a maximum temperature of 121°C. Thus, they are the go-to packaging for convenience, processed, and pre-packaged food.

The history of retort pouches

The idea for retort pouches was promoted by the US army in 1950 and the research continued through 1960. It was finally invented by United States Army Natick R&D Command, Reynolds Metals Company and Continental Flexible Packaging and was first introduced in Italy. These companies received the Food Technology Industrial Achievement Award for their invention in 1978.

These pouches faced a stagnation period in the beginning due to the reluctance of the people to accept them. However, over the years manufacturers and companies have realized that using retort pouches for packaging reaps many benefits.

 Inside of retort pouches

When we wax praises about how well retort pouches package, it is because of its internal structural composition. It has the sturdiness of metal cans and protects the nutrient value of the food. Specifically, each pouch consists of four layers as shown in the image below.

  • The first layer is propylene which acts as a heat seal surface and provides strength and flexibility.
  • The next layer which is the nylon layer protects from abrasion.
  • The aluminium layer not only protects from lights, gases, and odour but also extends the product shelf life.
  • The final polyester layer provides excellent strength and is very easy to print on.

The materials that go into the packaging of retort pouches are FDA approved and undergo sterilization processes which increase the durability of the packaging.

Material of retort pouches

The structure of the high temperature resistant cooking bag has two layers, three layers, four layers and even more.

Among them, the second layer is a transparent plastic / mold, such as PET / CPP or OPA / CPP.

The three layers are transparent plastic / mold, such as PET / OPA / CPP and opaque types containing aluminum foil, such as PET / AL / CPP, OPA / AL / CPP.

The four layers are opaque PET / AL / OPA / CPP with aluminum foil. This structure is a puncture-resistant, reinforced, large-capacity packaging bag. The OPA should be reasonable between AL and CPP.

The more layers are mainly The inner layer does not use pure CPP film, but uses multi-layer co-extruded film, such as PA / EVOH / PP, PA / PVA / PP co-extruded film plus PET or aluminum foil to form a composite with more layers, but its quantity Not much.

From a functional point of view, the four-layer structure PET / AL / OPA / CPP bag containing aluminum foil can completely meet the requirements of all cooked food.

For these materials used in cooking bags, it is necessary to introduce their properties and functions. In order to ensure the quality of cooking bags, specific requirements should also be put forward.

1. Polyester film PET, also known as biaxial (or biaxial) stretch polyester film

PET (or BOPET) film is used as the outer material of the cooking bag, and its thickness is 12 μm. It has the characteristics of high melting point, high heat resistance, high mechanical strength, high rigidity, high transparency, high odor resistance, and high gas resistance. Due to the polarity relationship in its molecular structure, the surface tension is high, and it is slightly increased. The surface tension after corona treatment can reach 52mN / m (ie 52dyn / cm), which is very favorable for printing and bonding.

When PET is used as the outer layer material and other heat-sealable materials (CPP, PE, etc.) are compounded to heat-seal bags, even if the temperature is as high as 220 ° C, it will not melt and deform, and will not stick to the knife. Bag making. At present, there are many PET film production suppliers in China. Most PET films can meet the high temperature cooking of 120 ~ 128 ℃, and even meet the high temperature cooking of 135 ℃. However, there are also some PET films with thermal shrinkage. Large, the problem of deformation after high temperature cooking. Therefore, when choosing PET for high temperature cooking, be sure to choose a product with a small heat shrinkage ratio, and then use it with confidence.

2. Aluminum foil AL

Aluminum foil is a metal material. Most of the soft aluminum foils with a thickness of 9 μm are used on the cooking bags. Airtight (O2, N2, CO2, etc.), opaque, and extremely high heat resistance and oil resistance, so the composite bag made of aluminum foil has a full seal (like tinplate cans), high security It has excellent properties such as oil resistance and high-temperature resistance. It is the highest-grade composite flexible packaging material.

stand up 1

3.Cast polypropylene CPP

In cooking bags, as the inner material that contacts food contents and heat-sealable bags, most of them are unstretched cast polypropylene films with a thickness of 70 μm to 80 μm. Only a few use high-density polyethylene ( HDPE) Manufactured at 121 ° C.

High temperature retort pouches – as one of the most commonly used cooking bags, its trial materials and standards may be higher. Do you know the high temperature retort pouches?

Whats High- temperature retort pouches?

“The high-temperature cooking bag is a kind of composite plastic film bag that can be heated. It has the advantages of both a canned container and a boiling water-resistant plastic bag. Sterilized and heated, ready to eat. After more than ten years of use, it is an ideal sales packaging container.

opener test

Types of High-temperature retort pouches

Classification by structure:

Class A: PA / CPP, PET / CPP. Amount of water vapor transmission: ≤15g / (m㈠4h); Amount of oxygen transmission: ≤120cm / (m2㈠4h0.1HPa).

Type B: PA / AL / CPP, PET / AL / CPP. Water vapor transmission rate: ≤0.5g / (m (4h); oxygen transmission volume: ≤0.5cm / (m㈠4h0.1MPa).

Type C: PET / PA / AL / CPP, PET / AL / PA / CPP. Amount of water vapor transmission: ≤0.5g / (m㈠4h); Amount of oxygen transmission: ≤0.5cm / (m㈠4h0.1MPa).

boiling pouch2

 Classified by cooking temperature

When the relative pressure is 110 psi, the corresponding temperature is l15cC; the shelf life is about 3 months.

When the relative pressure is Ps 1 15 psi, the corresponding temperature is 121cC; the shelf life is about 6 months.

When the relative pressure is PS 1 20 psi, the corresponding temperature is 126cC; the shelf life is about 12 months (transparent bag).

When the relative pressure is PS1 30 psi, the corresponding temperature is 135cC; the shelf life is about 24 months (aluminum foil bag).

Of course, the shelf life has a lot to do with the barrier properties of the cooking bag and the type of food.

However, those kinds of retort pouches are commonly used in our life right now while they do help to save the day! Let’s see:

Well-designed

Due to the sturdy packaging, these pouches are protected during transportation. Being lightweight, they also prove to be very cost-effective during transit. They can easily withstand temperature variations of up to 250 degrees and are leakage proof.

Resource-efficient

Retort pouches utilize just 5% of the packaging material and at the same time improve the food texture, flavor, and aroma. Also, the energy that goes into the production of these pouches is much less than what goes into making metal, paper or glass packages. They are made with high-quality materials and are environment-friendly.

WeChat Screenshot 20200201155335

Space-efficient

Retort pouches can stand upright on the shelves and this helps in maintaining the food composition inside. They are also flat and hence take up very little space on the shelf as well as in the shopping bags.

 

Combinedly, all of the above advantages serve to make retort pouches the go-to packaging, especially in the food and beverage industry.

Conclusion:

According to the introduction, the retort pouches are different according to the material and the number of layers. During use, you can also choose different specifications and types of cooking bags according to different cooking environments and foods.

It is undeniable that retort pouches are indeed closely related to our lives. In order to meet the current public’s pursuit of environmental protection concepts, many manufacturers have also started to develop green retort pouches.

PrimePac is a manufacturer specializing in packaging production. It pays attention to every detail from material selection to production. Technological innovation is productivity and it is your trusted cooking bag manufacturer.

About Primepac

Primepac is Australia’s number 1 choice for plain and custom printed high-quality packaging.

At PrimePac, we bring together design experts and brand innovators to create fresh ideas, customized packages, and fully efficient processes.

We design creative packaging solutions that cater to a diverse global audience with the in-house knowledge and network of experienced professionals to meet the demands of every type of client.

From our dedicated sales team and warehouse staff in Australia to the experts at our production facilities in China, all of our employees are guided by four core values at the heart of our business: integrity, innovation, passion, and engagement.