at Thu, 19 May 2005 22:48:14 GMT in <kj5q81ds748sqbscftd261l41fip5ka0qb@
4ax.com>, group (maxine in ri) wrote :

>I'm no expert when it comes to cooking with chocolate, just follow the
>directions and it works, mostly.
>
>Someone was telling me about a recipe she had that seized. It called
>for baking chocolate and margarine. One person advised her not to use
>margarine because it has water in it and that was why the chocolate
>seized.
>
>But I got to thinking, ganache uses cream and butter, both of which
>have some water content.
>
>Any help understanding the "chemistry" here would be appreciated.
>

Margarine would in and of itself probably not cause chocolate to seize. I
don't think it would make a good choice in terms of flavour and texture
(butter is a better choice) but that's a separate question. Water by itself
causes chocolate to seize because it forces crystallisation of the cocoa
butter in an undesirable crystal form and binds up the non-fat solids.
Cocoa butter has multiple crystal forms with slightly different melting
temperatures. When water is accidentally dripped into chocolate, it
instantly crystallises some of the cocoa butter into a random crystalline
form. Then, the water penetrates the non-fat constituents and glues them
together like cornstarch. The bad crystal shape meanwhile acts as a seed
which recrystallises the rest of the cocoa butter, thereby allowing the
water to clump even more of the cocoa... and you get a runaway effect.

Now, if you add liquids when they're warm, they won't recrystallise the
cocoa butter. And if the quantity of liquid relative to the quantity of
chocolate is reasonably high, instead of clumping up the cocoa particles,
it dissolves them into a smooth mass. Think again of cornstarch. If you add
enough water, and stir it in hot, you can make a smooth liquid rather than
an ugly, gummy paste - and this is basically what you do when you make
gravy. In a similar vein, you can safely melt chocolate in a reasonable
amount of hot water (try it! It works). This is why adding hot cream to
chocolate in ganache works, too.

The classic tactic of adding vegetable shortening to seized chocolate in
order to salvage it works because shortening contains emulsifiers that
break up the cocoa butter and penetrates the clumped-up cocoa. I don't
recommend this method except as a desperation tactic when you're out of
options - the best thing to do is throw the batch out and start again.

Margarine, butter, etc. should also not cause seizing because here the
moisture is suspended in a lot of fat. These fats stabilise the crystalline
structure of cocoa butter enough that it isn't so finicky (which is why,
for instance, you can make an icing using simply butter and chocolate and
it doesn't need to be tempered). The only risk with margarine might be, if
it has a LOT of water, and is melted rapidly, condensing steam might seize
up the chocolate before the fat could be mixed in. That's probably what
happened to your acquaintance - if she was using a double-boiler,
especially, it could have been condensing steam that was the problem.


--
Alex Rast

(remove d., .7, not, and .NOSPAM to reply)