Ah, food chemistry

Today I made the following:

• Raspberry paste
• Quince paste (which may or may not turn out; it’s cooling as I type, and I won’t know whether it’s too soft until after it finishes cooling)
• Reboiled the coconut fudge, it’s fine now
• Two batches of lemon-lavender-white chocolate fudge (the first batch failed)
• Gang mold of the dragon-pendant

The interesting part was the lemon lavender white chocolate fudge batch that failed.  It actually failed twice.  The first time, it failed because I added the lemon juice at the end of cooking, rather than waiting until it had cooled.  It crystallized instantly into big grainy crystals, and I had to reboil it.

The second time, I heated it to an adequate temperature (236 F, 2 degrees higher than called for in Shirley Corriher’s Cookwise) but it crystallized only into a very soft fudge.  My thought is twofold:

• There’s a LOT of fat in this particular fudge, between the  cocoa butter and the cream I used in place of milk.  Fat inhibits crystallization
• Sucrose (table sugar) + acid + heat ==> glucose + fructose.  The latter two are both invert sugars that don’t crystallize well, so heating the lemon juice in the mixture may have converted the sucrose to invert sugar, further reducing the crystallization of the fudge.

To get around these, for the second batch I boiled the syrup to a high 240F (to increase the amount of sugar in the solution), reduced the lemon juice in the microwave until it was about half the original volume (to avoid diluting the sugar with liquid), and added the lemon juice at the end, once it had already cooled to 110F.  This seems to have worked, although the resulting fudge is still pretty soft.  I’m low on Valrhona Ivoire (the white chocolate in the fudge), though, so if it fails, I won’t make a third batch.  I need some white chocolate for decorations et al.