Under Pressure

One of the things that I like about food so much is that it makes sense. I like science, and cooking is science. The potatoes are done when they’re soft because heat converts indigestible starch to digestible sugars. Cakes and quick breads are fluffy and light because the chemical reaction caused by baking soda and an acid creates carbon dioxide. Bread rises because yeast eats sugar and creates gas. It’s like a perfect equation of chemistry when so many raw ingredients come together in the right order with the correct application of heat to create something delicious.

I’m a nerd.

The problem is that most people, at least the people that I know from the states, don’t care about these things. They don’t think about how food cooks, as long as it cooks. Instead of learning a technique, they learn recipes. Recipes don’t teach you how to cook food; they teach you how to cook a single dish and nothing else. Unfortunately, that’s what Americans like. They are comfortable with cooking methods and ingredients that are familiar and easy to understand, as well as ingredients and recipes that are forgiving of inexperienced cooks. It is for these reasons why pressure cookers aren’t common in American kitchens.

A pressure cooker is basically a heavy pot with an airtight lid. Middle school science class dictates that the boiling point of water is not constant, and is affected by the pressure of the surrounding environment. If the pressure of a fluid being boiled increases, then the boiling point also increases. That’s because the water molecules that are becoming heated need to overcome more pressure to change into gas molecules and escape the pot. More energy is needed to do so, and thus, the boiling point is higher. If the pressure is lower (like when air pressure decreases with increased elevation), then less energy is needed to reach a boil, and the boiling point is therefore lower.

What does this mean for cooking? If you are boiling food to cook it in an elevated area like Palampur, then the temperature of the boiling water is actually less than 100 degrees Centigrade. That means the food will take longer to cook. Even if you are at sea level, food still takes awhile to cook by boiling. A pressure cooker speeds up cooking considerably, because the sealed container artificially increases the surrounding air pressure and increases the boiling point. It means that the water in the pressure cooker that’s being used to cook the food is much higher than 100 degrees centigrade. Higher temperature means faster cooking.

Really, a huge nerd.

If you’re worried about the whole pot exploding because of too much pressure, don’t. Any pressure cooker manufactured in the past 50 years, even in India, comes with a little valve on the top of the pot that releases a small amount of steam when the pressure increases to a certain point. As the steam is released, the pressure decreases a little, then increases again until it trips the valve and releases more steam. That way, the pressure that’s needed to blow up a heavy duty pot is never reached. That’s a good thing, because shards of hot metal exploding will really wreck your day, not to mention your wallpaper.

The problem is that they’re not ideal for precision cooking on the fly. You can’t see and observe the food as it’s being cooking, which means that you have to rely upon experience and memorization about the cooking times for various foodstuffs. That’s bad for Americans who like to know everything about their food and good for Indians who are really good at memorizing stuff without questioning it. Also, there are certain foods that normally require long boiling times: legumes, beans, pulses, tough cuts of meat, homemade stock from bones, whole potatoes, and the like. Americans typically don’t eat those foods much, and when they do, they’re usually packaged or prepared by somebody else. Think, when was the last time you cooked dry beans, homemade beef broth or lamb shank from scratch? Didn’t think so. On the other hand, these are the kinds of foods that Indians eat on a daily basis (minus the beef broth).

Besides that reason, pressure cookers are in every Himachal kitchen for two more reasons. First is that most of the state is elevated, and using a pressure cooker means that food takes the same time to cook no matter the elevation. The other very good reason is that it’s much, much quicker. Less cooking time means less fuel used. Less waste is a good thing.

I admit that before coming here, I was a little wary of pressure cookers, but I’ve gotten a bit more comfortable with them. In fact, yesterday I used it in a completely new way for people around here to create a confection common to South America called dulce de leche. It’s a fantastic concoction made from caramelized milk, and using a pressure cooker to make it is also a really really cool science lesson (if learning while cooking is your idea of fun). Caramel tastes really good, but that’s just caramelized sucrose. Milk contains lactose, not sucrose, which caramelizes differently and tastes even better. The traditional way to make dulce de leche is to combine a lot of milk and sugar and cook it over low heat for 4 hours stirring constantly until it has reduced by three-quarters. I don’t know about you, but stirring for 4 hours while keeping the gas on isn’t exactly my idea of a good time.

Worry not, there’s a shortcut. Take a normal metal can of sweetened condensed milk, put it in a pressure cooker, cover it by at least an inch of water, and cook it for 40 minutes after the valve starts whistling. No, I’m not an idiot (Shammi looked at me like I was one when I showed him what I was doing). Yes, boiling a sealed canister normally is a really bad idea. Not this time. If you just put an unopened metal can over heat, it’ll explode. But by using a pressure cooker, the increased pressure created inside the can of condensed milk while it heats, which would normally cause it to blow up, is counteracted by the pressure created by the cooker. That’s why you have to cover it completely by water, so the force is evenly distributed all the way around the can.

Yes, I’m a nerd, get over it!

After the cooker is completely cooled, you can open it and take out the can. Don’t try to speed up the process by pouring water over it, and don’t even think about opening the can until it has completely cooled, because if you rush it, then the can will explode and you’ll be sorry. It’d be best to cook it at night, turn off the heat, and wait until morning to even touch the pot. Your patience will be rewarded with a delectable treat that you can use to fill a cake, spread over toast, pour over ice cream, whip into frosting or (my favorite) just eat off a spoon. All because you used a little bit of science and technology and bothered to learn about why something cooks instead of just how to cook it. Just wait, soon you’ll be as much of a nerd as I am.

In the food business, it is often said that if you want something, you can have it fast, good and cheap, but you can only pick two of those. With a pressure cooker, you can have all three.