Tuesday, June 24, 2014

Towards a Theory of Chinese Marinades: Part 5, Cornstarch

Cornstarch has become very popular in Chinese marinades. Martin Yan uses it in just about everything on his shows anymore, usually with the description of it making the meat tender.  It's viewed and used as the great secret to tenderness. I'm not convinced.

Texture is certainly important to Chinese cuisine. Texture is managed in many ways: drying, soaking, brining, how it's cut, how its cooked, velveting...

OK, velveting. That's cornstarch and it is a tender texture technique. Is it marination or is it battering and par frying / boiling in water.

Can you reduce the velveting effect to just including cornstarch in the marinade?

Does the order of using cornstarch matter? Some people think so. http://chinesefood.about.com/od/poultryreceo/r/moogoogaipan.htm

Note the emphasis on adding the corn starch last.

And also again in their beef and broccoli
http://chinesefood.about.com/od/beef/r/beefbroccoli.htm  I've noticed that Martin Yan tends to add it last, but have not seen him explicitly call for it to be added last, though it is often last in his list of ingredients as well. I've seen no explanation for this but it seems to me it's the easiest way to avoid clumping of the corn starch.

Hsiang Ju Lin notes two uses of cornstarch for controlling texture in his classic Chinese Gastronomy. One is described as "To preserve the natural delicate texture. To form an impenetrable barrier between meat and hot oil". The sample recipe is velveted.

His other  is "To bind juices of meat with seasonings. It is essential to add liquid at last stage of cooking."  The example recipe is marinated with corn starch and liquid is added at the end. In the recipe description, he indicates the corn starch seals in the juices.  I suppose juiciness is a related trait to tenderness but it's not the same thing.

At yet another point in Chinese Gastronomy, he notes that the cornstarch keeps the juices in the meat, to keep the juices away from the other ingredients. He had just finished discussing how in a longer cooking time, the juices from the meat run out and into the dish making everything taste of beef--a more western idea of unified flavors rather than contrasting flavors. And it's one of they key skills in stir frying to not cook anything to the point where it's juices run out. This is hard in the west with our lower output stoves and things tend to steam if one isn't careful in loading the wok.

Similarly, Cook's Illustrated opines (via lthforum.com)
The Mysterious Powers of Cornstarch Most cooks keep a box of cornstarch on hand for a single purpose: thickening. So did we - until we noticed that cornstarch was working its magic in other ways as well. Predictably, adding cornstarch (3 tablespoons) to our soup thickened it. What was surprising, however, were the two other uses we found for cornstarch. Adding just 1 teaspoon of cornstarch to the pork marinade of soy sauce and sesame oil caused the marinade to cling to and coat the meat during cooking, creating a protective sheath that slowed the inevitable rise in temperature that separates moist, tender pork from dry, chalky pork jerky. And adding just 1/2 teaspoon of cornstarch to the egg that's drizzled into the soup at the end of cooking seemed to have a tenderizing effect. Cornstarch stabilizes liquid proteins when they're heated, staving off excessive shrinkage and contraction. So this last bit of cornstarch helped the eggs cook up lighter and softer.

Or with a little variation alongside the Hot And Sour Soup recipe in "The Complete America's Test Kitchen TV Show Cookbook ". Click the image to read it in a bigger format.



And I agree that cornstarch in the marinade can help seal up the meat's juices. But I don't think it is the same end effect as velveting as is so often portrayed.  Also, it's use as a crutch over practicing good technique is saddening. Adding starch tends to cloud flavors. There are times the benefit of retained moisture outweighs the negative impact on flavor and it should be used. But it's not a universal solution to improving every marinade.  Before you just blindly add it because the recipe calls for it, or you've heard how great it is, try to understand what it will accomplish in the recipe. It might well be better without it.

One last note. Cornstarch is a relatively recent product of the west. Corn is native to the Americas and while there is a theory that corn was in China before Columbus came to the Americas (see http://yakushi.pharm.or.jp/FULL_TEXT/125_7/pdf/583.pdf) it could be the usage is generic as corn is in English for grains. Corned beef as a term similarly predates the Americas and referred to the size and shape of the seasoning spices. Or early English editions of the Bible use corn as generic for grain in the Old Testament which also would not have used corn in the modern sense. In any event, the early starches used in China before corn were from water chestnuts and millet primarily. (Harold McGee On Food and Cooking)

Other posts in the Marinade series:
Part 1
Part 2
Part 3

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