Chemical reactions in cooking
I've noticed that if I puree raw onions before sauteeing them they turn increasingly green as they cook - and they have a harsh smell until they brown (with garlic, cooked in a stainless steel pan). If I chop them fine, they don't go green, nor do they smell strange. I'm guessing that pureeing them breaks down the cells and some chemical is released that causes the colour change?
And today I made an aubergine (eggplant) puree with mint, garlic, fresh chillies and tahini - it was a dull brown-green-purple sludgy colour till I added lime juice - then it went a quite vivid pink. I'm guessing a reaction to the acid - but I've no idea what turns pink in acidic conditions.
Anyway, it got me wondering if there are any recipes that depend on a chemical reaction. I can think of cinder toffee (I'm not sure what that is called in the US) - and fermentation (cheese, alcohol) - but are there other ways to play chemistry sets in the kitchen? Is it possible to make something toxic by cooking unusual combinations?
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Paulustrious
Jun 22, 2010 04:36 AM
There are a number of plants which are poisonous unless cooked / prepared properly. A number of beans fall (such as kidney, soy and fava) in this category, as do certain fungi and tapioca.
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Caroline1
Jun 14, 2010 10:10 PM
A rather famous chemical reaction in cooking takes place in ceviche. Cooking with citrus. All leavening is a chemical reaction (or biological in the case of yeast) that releases air pockets within a batter or dough while cooking that increased its mass. Cooking is all about better taste and texture through chemistry!
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re: Peg
Caroline1
Jun 15, 2010 02:53 PM
Sheesh! I'm slowly giving up all of my bestest recipes to these boards, but here's one that come close to matching your criteria of two mixtures that aren't so great by themselves but are fantastic when combined and cooked. Oh, and the cooking combines compounds A and B into compound C. Neither one is quite on the "oh my god, that's disgusting!" side all by themselves, but they aren't exactly something you want to go sit down and cozy up to with a big spoon.
Things you need: a well buttered 9" X 9" baking pan, Pyrex or metal. And two bowls. Oh, and a couple of knives. a spoon and/or a fork to mix or fluff things. And preheat the oven to 350F. So...
FIRST BOWL: Put in 2 cups of sifted flour, 2 cups of well packed brown sugar (light or dark, doesn't matter), and 1/2 cup of butter or shortening. I don't advise margarine. With the two knives, cut the mixture the way you would pie dough until it's the texture of corn meal.
SECOND BOWL: Mix together 1 cup of sour cream, 1 teaspoon of baking soda, 1 egg (beat it before adding) and a teaspoon of nutmeg, freshly grated if you can manage.. Mix well until smooth.
Now get the well buttered 9" X 9" baking pan and put half of the first mixture in it. Pack lightly but NOT too tightly. Just smooth it out and that should basically do it. Now ever so gently pour the contents of bowl #2 over the mixture. DO NOT STIR OR DISTURB! Now gently distribute the remaining contents of bowl #1 evenly over the top. DO NOT PACK DOWN! Now bake it for about 40 minutes in a 350F degree oven. Take out and allow to cool. Cut into squares and serve.
Some history to this recipe. It was a very popular dessert back in the middle of the twentieth century at George Mardikian's "Omar Khayyam's" restaurant on Powell Street in San Francisco. It burned down years ago, but it was a famous and truly great restaurant. I don't know exactly how my mother came by this recipe in the late forties or early fifties -- possibly from Chef Mardikian himself? -- but it has been a treasured family favorite for well over half a century. Amazingly simple. Divinely delicious! I don't make it all that often because when I do, if someone else gets to it first, that's the end of it. And if I cook when I'm going to be the only one around, that's the end of it. But I end upwearing it!
Anyway, Peg, I think this comes as close to your criteria as I can get. You've got to promise to try it at least once. Enjoy.
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re: Caroline1
buttertart
Jun 17, 2010 06:13 AM
Oh Caroline1, this sounds absolutely sublime, thank you for the recipe - I must make it this weekend. I remember the restaurant from early days in Berkeley...a Herb Caen hangout, wasn't it?
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re: buttertart
Caroline1
Jun 17, 2010 06:36 AM
Probably. I used to read him, but don't know that I'd have recognized him had he bit me! Mardikian's was a top restaurant in SF for many many years. I loved the place. And it has the supreme distinction of being the ONLY place my husband and I were trying to get to on foot, only to be engulfed by the wonderful dragon in the Chinese New Year Parade! Wound itself around us in the middle of a pedestrian crosswalk! We could hear giggles coming from it. Very playful guys under that dragon suit! And I'd wrestle a dozen dragons to get to dine at Omar Kayyam's one more time. GREAT food...! Enjoy the cake. I'm trying VERY hard NOT to make it...! '-)
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re: Caroline1
buttertart
Jun 17, 2010 06:47 AM
Great only-in-SF story! We left Berkeley in 1987 for the east coast and have yet to find our way back to the garden...one of these days, we hope. I vaguely remember having eaten there once but we were at Cal and on a very restricted budget, not too many splashouts at the time. Can't wait to taste the cake.
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re: buttertart
cosmogrrl
Jun 20, 2010 08:05 PM
I remember Omar's. Loved it. Bring's back memories of dinner with my parents.
buttertart, my advice is that unless you want to come back to an area that has changed drastically since '87, stay away. Breaks my heart sometimes to see all the changes sometimes. And not always for the better! If you want to see the "new" SF then please do come, but it's really hard to see everything so different sometimes. And I'm not even that old, I'm only in my late 30's. I go through areas that are completely unrecognizable from even 10 years ago. Many people here seem so hell bent on changing everything and that even means changing the "old" stuff from, say, 5 years ago. *sigh* Maybe my inner curmudgeon is beginning to show...
Caroline1 thanks for the memory and thanks for your recipe!
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re: cosmogrrl
buttertart
Jun 21, 2010 09:05 AM
Yes I've noticed it's not at all the same when we go back to visit (have friends from when we lived there), but it is still one of the nicest places to live in the US as far as climate and food are concerned. Not that I spend all my time pining for it, but there are places I'd like to have access to at shorter travel time than a 5-hr plane trip! (Berkeley Bowl comes to mind). You know the grass is always greener...
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re: Caroline1
Peg
Jun 19, 2010 02:04 AM
No chance of that - company No 1 went belly up taking my money with them. I have been without a 'proper' kitchen for almost 2 years. It is now due to be completed next month, so I'll be able to cook in my own house again and I'll not have to invite myself to friends houses to cook them dinner!
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re: Peg
Caroline1
Jun 19, 2010 01:57 PM
Oh my god, and I thought I had it bad with a painter who didn't know how to paint, painted a second time to try to rectify the first, failed miserabley at that and then put all thirty kitchen cabinet doors back on the wrong cabinets. Nothing fits! When I told him I wanted him to make it right, his response was, "So sue me." When it comes to "Kitchen Nightmares" we can both go sit next to Gordon Ramsey!
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maria lorraine
Jun 14, 2010 04:15 AM
"The discoloration is due to pigments that form between sulfur compounds in garlic and amino acids. When the garlic tissue is disrupted, as happens in processing, an enzyme is liberated and reacts with it to form thiosulfinates compounds that then react with the natural amino acids in the garlic to form blue pigments. The age of garlic determines how much isoalliin there is in the first place, and the nature of the processing determines how much enzyme is liberated."
Source:
Identification of Two Novel Pigment Precursors and a Reddish-Purple Pigment Involved in the Blue-Green Discoloration of Onion and Garlic, Journal of Agricultural and Food Chemistry, 2006, 54 (3), pp 843–847 DOI: Publication Date (Web): January 12, 2006.›7 Replies-
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re: FoodFuser
maria lorraine
Jun 15, 2010 12:05 AM
Here's my post again. I asked for the mods to delete a leftover scrap from my post, and the entire post get deleted.
I have front-door access to several journals, but for those to which I don't have access, Google Scholar is a good source. I type in "full text" into the search window, but often the abstract is all one needs and this food chem stuff can get pretty hairy.
The reason for the green color:
In pureed onion and garlic, there are two pigment precursors (not the colors themselves) and a purple pigment. When the purees combine, the pigments express and the color changes from purple to blue and then green.Though it's no bedtime reading, here's the passage from the abstract (edited) that describes this:
"By using a model reaction system representing blue-green discoloration that occurs when purees of onion and garlic are mixed, we isolated two pigment precursors (PPs) and a reddish-purple pigment(PUR-1)…[that] form conjugated pigments [and] a color shift toward blue to green can be expected as the cross-linking reaction continues to form."Good luck. If you need more research tips, please feel free to ask.
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re: maria lorraine
Paulustrious
Jun 15, 2010 07:26 AM
This is all technically correct. I absolutely concur with tastesgoodwhatisit, McGee's book is a treasure. 1000 pages that tell you a lot about food and cooking with nary a recipe in it. It explains the 'why' rather than the 'how to'. And finally it has 15 pages of references arranged by chapter.
Almost all the alliums have a defensive mechanism built in. Upon being crushed and the cell walls destroyed, the binary weapons of garlic jump to its defence. This rich morsel of food attempts to protect itself from larger predators. Try eating a whole one. (Chews carefully).
If you slice garlic less damage is done and the flavour is much less harsh. If you pulverise garlic you will maximise certain flavours, but that is not necessarily what you want. It is fine for longer cooking, currries etc, but in terms of raw garlic it is usually way over the top.
The colour also depends on what you cook with it. Slow cooking in olive oil will show more green. And if you really want the green colour then pickle the garlic in vinegar for a fortnight.
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A really good book to check out, if you're interested in this sort of thing, is On Food and Cooking: The Science and Lore of the Kitchen by Harold McGee. Tons of info on chemical reactions in cooking - for example, the browning of meat is a well known chemical reaction, as is the way that meat sticks in a pan at first, but loosens if you leave it for a few minutes.
As far as the colour changes go, I do know that purple cabbage changes colour when you add acid, as the juice is an acid-base indicator. And when you make pickled ginger, it goes pink when you add lime juice.
