Between On Food and Cooking and CookWise you would think one would cover the topic of “binders” but NO – I’m left to my own devices. Internet searching for “food binders” gives some interesting results but no definitive reference – not even a Wikipedia article.
Binders are used in a number of meat mixtures – meatloaf is probably the best example in my mind. Not surprisingly I found an article about making meatloaf in which Alton Brown talks about binders – finally! However, beyond the basics there’s no discussion on ratios, applications, etc. Even before reading the article I was starting to think about binders like I would emulsifiers – their job is to hold together a mixture that otherwise would fall apart.
After reading the article and browsing a few recipes that included binders – meatloaf, crab cakes, etc. there seem to be only a few “natural” items that are considered binders – eggs, dairy products, and starch. Like double action baking powder, there are two kinds of binding that need to happen – one at mix time and the other at cook time. After all, if you can’t get it into the pan as a unit, you can’t cook it.
Starch, in the form of breadcrumbs, crackers, etc, would be active in the mix phase since they will soak up moisture, swell and stick to the foods that surround it. I’m guessing that too much starch and the mix will crumble apart since all the moisture will be gone. When cooked, the starch will expand and perhaps explode spewing the starch grains in the mix and tighten things up further.
Dairy, milk and cream in particular, seem to denature during cooking, although I suspect that acids and salt can get the process started sooner. Unlike eggs, I don’t think air alone can cause denaturing in dairy. It would seem then that other than providing moisture, dairy doesn’t contribute much at the mix phase, but can play a roll during heating/cooking. Dairy can also be an emulsifying agent.
The proteins in eggs will start to unravel, tangle and thicken somewhat in the mix phase, especially if exposed to air, acid and salt. This denaturing process will allow the egg proteins to tangle with each other and thicken the mix. Since they are a natural emulsifier, they will bond to watery and oily substances. When cooked they will tighten and pull the items they are bonded to together. Salts and acids also cause eggs to thicken at lower temperatures, but dairy raises their thickening temperature. Humm…
Chef Paul’s recipe calls for all three binders – bread crumbs, eggs and cream – all at mix time. No doubt that cream is being absorbed by the breadcrumbs but those crumbs are also absorbing liquid from the eggs, crab meat (the recipe doesn’t call for draining), and other liquid items hanging around. All 3 binders are added at the same time – right at the end before letting the mixture rest for 1.5 hours. The resting phase would seem to be there for the starches in the breadcrumbs to absorb the liquids and swell as well as give the eggs a chance to denature and begin to bind with each other and the surrounding mix.
Whew.. almost as complex as baking, which is probably why binders are not an exact science. Too much is dependent on the kind of liquid, the absorbency of the starch, what the eggs are exposed to (and when) and the temperature at which the dish is cooked.
An interesting experiment would be to add breadcrumbs to a wet meat mixture and see at what point it begins to “fall apart” – if it does. I think I’ll give that a whirl with tuna and some ground crackers.
