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In the world · Food · 23 December 2025

Autoclave and retort pouch: safe food without a fridge

The retort pouch, sterilized in an autoclave, won an award in 1978 and keeps evolving in the U.S. Army. How it works and what it needs before the table.

bairogonzalez.com team, drawing on Bairo's story · Published

The retort pouch is a flexible pouch in which food is sealed and then sterilized in an autoclave, under heat and pressure, so it lasts at room temperature without preservatives. The technology won an award in 1978 in the United States and is still evolving: in December 2025, the U.S. Army reported that a new, lighter pouch without an aluminum layer had passed safety tests.

What happened

The story begins with military rations. In the 1950s, the U.S. Armed Forces food institute, predecessor of today's Natick center in Massachusetts, saw the sterilizable pouch as a lighter alternative to the can. Development brought together the Army and two packaging manufacturers, Reynolds Metals and Continental Flexible Packaging. In 1978, the three jointly received the Food Technology Industrial Achievement Award from the Institute of Food Technologists, recorded in the journal Food Technology that year. In Japan, Otsuka Foods had been selling a retort-pouch curry, Bon Curry, since 1968.

In 1981, the New York Times asked whether the pouch would be the new tin can. The answer came gradually: today it is in military rations, emergency kits and on supermarket shelves in several countries.

The principle is the same as canning. According to the standard technical description, the food is sealed in the pouch and heated to somewhere between 116 °C and 121 °C, for a few minutes, under high pressure, inside an autoclave. Under pressure, water goes past 100 °C without boiling, and the heat reaches the center of the already packaged product. Time and temperature are calculated to eliminate common microorganisms, including the spores of the botulism bacterium, Clostridium botulinum.

On December 23, 2025, the U.S. Army described the current state of the technology in combat rations. The standard pouch has three layers of polymers and one of aluminum, which blocks water vapor, oxygen and light. Researchers at the Natick center developed lighter polymer blends without aluminum, and a seven-year project with this pouch passed safety tests. Engineer Danielle Froio-Blumsack sums up the process as a relative of pasteurization and canning, which extends shelf life without preservatives. The same group works with NASA on long-lasting food for missions to Mars.

Why it matters

Much of the cost of getting food to those who need it lies in keeping it cold. Refrigerated trucks, cold rooms, constant power. A food that is stable at room temperature can be stored in any warehouse, travel far and wait months in a pantry. For communities without stable refrigeration, shelters and disaster-hit regions, this changes the entire logistics.

There is a caveat that needs to be clear. Shelf life is not a packaging promise. It is proven, product by product, with calculation of the thermal process, control of each batch and a stability study, which follows the food over time to see whether it remains safe, nutritious and acceptable. In the United States, low-acid food in hermetically sealed packaging has its own rule for the thermal process. In Brazil, each product goes through the sanitary rules of Anvisa (the health regulator) and, where applicable, of the Ministry of Agriculture. Without that, no expiration date holds up.

In Bairo's view

For Bairo Leandro Gonzalez Martinez, the autoclave is a good example of down-to-earth innovation: an old, known and tested technique, used for a new problem. In his reading, there is no need to invent a science to make use of the supply centers' surplus. What is needed is to bring a science that already exists close to where the food is left over.

He also likes the technology's origin. In Bairo's view, if a pouch was able to feed soldiers far from any refrigerator, and is now being studied for space missions, the same logic can serve a community kitchen, a shelter or a family that lives far from the city.

Where this meets the ecosystem

Instituto CEASA, the humanitarian front founded by Bairo, proposes a factory that uses the surplus of the wholesale supply centers as raw material and the autoclave as the process. The design's goal is a food that lasts up to two years without refrigeration. Until there is a stability study and sanitary registration for each product, that shelf life is a project goal, not a proven characteristic. Stated website: institutoceasa.org (site under construction).

The Institute's technical question already has an answer on its own page: how food lasts two years without refrigeration.

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