I got to wondering about the word retort as I was preparing a bowl of "premium" tom yam instant noodle soup. (Yes, even I, dedicated gourmet cook, sometimes resort to instant noodles: but premium! Only premium!) Alongside the little plastic pouch of hot chili powder, and the bigger one of nam prik phao, and the even bigger one of dried shrimp and vegetables, was a very big flexible foil pouch, labelled in Thai and English "retort pouch". (The Thai just sounded out the English words in Thai characters.) It contained a weird goo surrounding some sliced straw mushrooms, two mussels, and some squid rings. Yum! (Well, except for the goo.)

But clearly this kind of retort has nothing to do with the one that I know, which is a witty riposte, a quick comeback, a sharp reply. So I thought I'd do some investigating as I waited the requisite three minutes for my soup to "cook".

Turns out that retort has technical meanings as well. A retort is a vessel, often glass, which is used to heat solid or semi-solid substances in order to distill or decompose them; it typically has a bulbous body and a downward curving neck. A retort is also a cylindrical refractory chamber used to heat coal or ore. To retort is to sterilize food after it has been sealed into a container, and here at last we approach the retort pouch, which is a kind of flexible can or tin. It's a pouch made of layers of film or aluminium foil into which food is placed; once the food is sealed into the pouch, the food and the pouch itself are subject to very high temperature and pressure, sterilizing both pouch and food. Food in retort pouches can last without refrigeration or preservatives for 18 months. It will not surprise you that retort pouches were developed for the Apollo space program and are still used today for military MREs. I'm not thrilled about the latter, but confess that it warms my heart to know that eating my instant tom yam brings me that much closer to those nutty explorers of the modern world, the astronauts.

And by the time I found all this out, I'd polished off the soup, which was delicious.