A marble slab or other cool flat surface is essential. Work from one end of the marble to the other, and then back again so that the temperature of the marble remains stable. At the end don’t be tempted to scrape off the hard bits from your palette knives as this will mess up your tempered chocolate – leave for consumption later, or give them to any willing helpers to lick. A stable room temperature of 20–24°C helps as does low humidity, less than 50 per cent. Different chocolates have different tempering curves. The precise temperatures vary with each chocolate. This is a technical point, and most manufacturers supply this information to anyone who needs it, as it is pretty important to get good results.
For most real dark chocolate, the starting temperature of the melted chocolate should not exceed 58°C. For milk or white chocolate, 50°C is the upper limit, because of the cassein, or milk protein, they contain. This protein is very sensitive to heat and will suddenly seize up at 54°C, rendering the chocolate useless.
Couverture is the technical name for the best-quality cooking chocolate, not to be confused with ‘covering’ chocolate which does not deserve to be called chocolate. Couverture must contain at least 31% cocoa butter. This rich chocolate is very fluid in its molten state and easy to work with, yet is very crisp and brittle when tempered.
© 2003 Chantal Coady. All rights reserved.