Alex Rast wrote:

> Adding sugar is to some extent somewhat defeating the point - why not just
> use 70% instead? Perhaps the only reason you might decide to do so is if
> you were completely out of 70%, with no hope of rapid resupply, and had
> prior, urgent commitments you couldn't alter.
>
> ...
>
> If you add a small amount of invert sugar or corn syrup, this will improve
> your texture. Don't go crazy, however, or the truffles will become soft,
> and eventually will never solidify, remaining as a sauce. Another poster
> recommended honey and this also works but requires similar discretion as
> invert sugar/corn syrup: going overboard will soften the truffles
> unacceptably.
>

Valrhona have a range of "grand cru" couvertures ranging in cocoa
content from 64% to 72% (cocoa butter from 40.5% to 43.5%; sugar from
36% to 28%). These are delicious, distinctive, and well balanced
couvertures. I use them to create fresh cream ganaches.

I continually experimented with recipes, the results of which are
critiqued by a regular tasting group of 50 plus people. I recently
trialled a pure cocoa ganache - five different recipes; tasted at one
week old, and then again at four weeks old.

At the first tasting, tasters overwhelmingly preferred (A) a near 1:1
ganache (chocolate:cream) with no added sugar. But three weeks later
this chocolate had dried significantly. Tasters now preferred (B) a
3:2 ganache with 7% added invert sugar. Interestingly, the original
first choice (A) had become tasters' least preferred, and conversely
what had been the least preferred (B) came out tops at the second
tasting. Compromises (C) and (D) based on 3.5% added invert sugar made
up the middle ground; as did (E) a 1:1 ganache with 7% added invert
sugar (less chocolate to compete with the added sugar than the 3:2
ganache I guess).

Thus my dilemma - how to create the perfect pure cocoa ganache, one
which conveys, unadulterated, the distinctive, well based taste of its
constituent couverture (ie ganache A in our tasting). But also one,
which lasts at least four weeks in tip-top condition.

Could this be an advantage of 99% dark chocolate? As Alex points out,
sugar can be added to taste, a percentage of which could/should be
invert sugar. Two downsides: 1) the choice of couvertures at 99% is
far less than that at circa 70%; 2) the ability to create a ganache to
show case a producer's (eg Valrhona's) distinctive, and well balanced
couvertures is lost.

Alternatively, is their a humicant other than those based on sugars
(eg invert sugar, honey), whose inclusion with a chocolate ganache
decelerates the drying out of chocolate centres?

Simon