Monday, January 12, 2009

Food Composition and Cooking Method

Last week I studied food composition and cooking method, subjects which didn't interest me as much as I expected. I spent most of last week going back and forth between Harold McGee's book, On Food and Cooking, and Shirley Corriher's Cookwise. Usually, what I read in McGee made no sense because it was overwhelmingly science-oriented and he did not connect it to cooking. But what I read in Corriher lacked details. By Friday, I had bits and pieces of new cooking knowledge, but I was struggling to understand how it all fit together.

Which is why I put off posting for so long. Rather than try to create a new meal, I ended up paying closer attention to what I was already cooking for meals. For example, I made black bean and acorn squash empanadas on Saturday (Veganomicon). As I was about to put the squash in the oven to cook, I realized that I could caramelize it. I already had the basic preconditions for caramelization: high temperature (400 degree oven), long cooking time (50 minutes), a non-acidic environment, and proteins. All I needed was some glucose for browning. I brushed maple syrup onto the squash, and popped it in the oven. Fifty minutes later I was surprised that it had browned. It was too crispy to mash up for the inside of empanadas, so I scraped it off and we ate the caramelized part as it was. It was sweet and delicious.

On Sunday I sautéed chopped white onion to go on a pizza. It wasn't cooking quickly enough, so I thought back to a passage from Corriher that recommended salting boiling water to hasten the cooking time of some vegetables. (Cooking time is 10% faster with salted water). I wasn't boiling the onions, but I still tossed in a ¼ teaspoon of salt into the pan. I noticed the onions did cook a little quicker, but even more noticeable was that the onions softened considerably. They were very translucent. I'm not sure, but I believe salting forced the water in the onion cells to leak out faster, causing the chopped onion to soften and become translucent in a few minutes over medium-heat.

Today for lunch, I sliced four large waxy potatoes into French fry sticks to make spicy Cajun oven fries (Vegan with a Vengeance). Two potatoes were room temperature, like I always use when making oven fries. The other two had been sitting in the refrigerator for a day, as per Corriher's suggestion for making crispier fries. When chilled, starch converts to sugar. Sugar burns at a faster rate than starch. For deep-fried French fries, this conversion is a disaster because the outside will brown before the inside if truly cooked. For oven fries, this conversion is genius. They will brown and cook at equal rates, but will ultimately brown better than room temperature potatoes. Another trick Corriher suggests is to pat dry the potatoes before cooking in the oven. Drying the potatoes removes water that starch would otherwise absorb. If the potatoes are dry, the starch will suck moisture out of the potato until the surface is dry. Corriher describes this as "sealing" the potato. It also prevents grease from soaking into the potato sticks. So, I placed the room temperature potato sticks on one pan, and the chilled potato sticks on another. I expected the chilled potatoes to be crisper and less greasy.

I was right! At left are the room temp potatoes; at right are the chilled. The room temp potatoes browned, but it was uneven. The inside was also crumbly compared to the chilled potatoes – perhaps because the starch didn't seal the exterior?

This past week I learned a lot, but it will take time for me to apply everything in my cooking.

I learned...

  • why steaming is so effective

  • why lipids don't dissolve in water

  • why some vegetables are refrigerated and others are not

  • that cooking is literally cell death by rupturing membranes and leaking out water

  • sugar helps fruit retain its shape when cooked by slowing down the conversion of pectin around the cell walls. (This must be part of the reason why you toss apples and sugar together to make apple pie filling?)

  • blanching is not a cooking method, but rather a technique to brighten up vegetable colors and to loosen fruit skins

  • why my mashed potatoes fail consistently: I haven't been precooking and rinsing off starch!

But I was still confused and/or need to learn more about...

  • why roasting carrots makes them sweeter but pan-frying them doesn't. Why do sugars break down from double compounds into single compounds in the oven but not in the pan?

  • braising meat. Will it work with mock meats?

This week is baked goods! Get ready for food porn. I bought a used digital camera, so the photos ought to be decent. Don't worry – I won't post anything that's blurry or dark.

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