What Is Retort Food? How Ready-to-Eat Meals Keep for 12 Months Without Preservatives

In short: Retort food is food that is cooked, sealed in an airtight pouch and then heated to 121°C under pressure until even the centre of the pouch is sterile. With nothing alive inside, and a foil pouch that keeps air, light and moisture out, it stays safe at room temperature for months. That is why a Thakar Kitchen pouch keeps for 12 months without a single preservative.

If you have ever picked up a pouch of dal or curry that sits on a shelf, not in a fridge, and wondered how, this is the answer. It is not a chemical trick. It is heat, pressure and good packaging, the same idea as canning, made lighter and faster.

Where does retort food come from?

Sealing food and then heating it is more than 200 years old: it is how canning works. The retort pouch, a flexible, flat pouch in place of a tin can, was developed in the second half of the 20th century for military rations and space food, where meals had to be light, tough and safe for a long time without refrigeration. Today the same method is used for ready-to-eat meals all over the world. You can read more about the retort pouch on Wikipedia.

How does it work, step by step?

1. Cook the dish. In our kitchen in Morbi, every dish is cooked first, in small batches, the way it would be at home.
2. Fill and seal. The dish goes into a multi-layer foil pouch, the air is pressed out and the top is heat-sealed. The food is sealed before it is sterilised, so nothing touches it afterwards.

   

3. Into the retort. The sealed pouches are laid flat on trays and rolled into the retort, a steel pressure chamber that works like a very large, very precise pressure cooker.

   

4. Heat to 121°C under pressure. The retort holds the pouches at 121°C until the very centre of every pouch has reached that temperature.
5. Cool and check. The pouches are cooled while the pressure comes down, so they keep their shape, and each one is checked for a good seal.

   

You can see how every pouch is made, step by step on our FAQ page.

Why 121°C and not just boiling?

In an open pot, water cannot get hotter than 100°C. Boiling kills most bacteria, but some bacteria leave behind spores: tough, sleeping seeds that survive 100°C and can wake up later to spoil food or make it unsafe. Under pressure, water can get hotter. At 121°C, held long enough, the spores die too. The food is then what food scientists call commercially sterile: nothing is left alive in it that could grow at room temperature.

Why are no preservatives needed?

Preservatives slow microbes down. In a retort pouch there are none left alive inside, and the sealed pouch stops new ones getting in. With nothing to slow down, there is nothing for a preservative to do. In one line: nothing alive inside + nothing gets in = nothing to preserve against.

What does the foil pouch do?

A retort pouch is several layers bonded into one: polyester on the outside for strength, a layer of aluminium foil that blocks light, air and moisture, nylon against punctures, and food-safe polypropylene on the inside that seals to itself and stands up to the heat. The foil is the barrier. As long as the seal is intact, the food inside stays as it left the retort.

Does retort food taste like fresh food?

A flat pouch heats through much faster than a can, so the food spends less time in the heat. Indian dals and curries are slow-cooked dishes anyway, which is why they suit the process so well: a Gujarati Dal or a Paneer Butter Masala tastes the way it did when it went into the pouch. Delicate, crisp things (a fresh salad, a crunchy pakoda) do not suit it, and we do not try to make them.

How should I store and heat it?

Keep unopened pouches in a cool, dry place: a shelf, a cupboard, a bag. No fridge is needed. To eat, drop the sealed pouch into boiling water for 3–4 minutes, or open it into a pan and heat for 2–3 minutes on a medium flame. Our guide on how to heat a ready-to-eat pouch has the details. Once a pouch is open, it is fresh food again: eat it straight away.

Questions people ask

Is retort food safe?

Yes, when the pouch is intact. The 121°C process makes the food commercially sterile, and the sealed pouch keeps it that way. Do not eat from a pouch that is swollen, leaking or damaged.

Does retort food contain preservatives?

It does not need them. Thakar Kitchen dishes are made with no preservatives and no added colours; the ingredient list is on every product page.

How long does retort food last?

Our pouches keep 12 months from manufacture, unopened, at room temperature. Once opened, eat it straight away.

Is retort food the same as canned food?

It works on the same principle (seal first, then sterilise with heat), but in a flat, light pouch instead of a can, which heats through faster and is easier to carry.

Can I microwave a retort pouch?

Not in the pouch: it has a layer of aluminium foil. Empty it into a microwave-safe bowl, cover it and heat it, stirring once.