What Should You Know When Chopping or Grating Chocolate?

To cut chocolate into neat pieces, lay the block on a flat surface and slice it with a wide knife using a sawing motion; holding the knife upright and pressing straight down breaks the chocolate into uneven pieces and sends shards flying. Chocolate cuts most cleanly at room temperature, 18–20°C / 64–68°F. Grating requires the opposite: chilling the chocolate in the refrigerator for 15–20 minutes before grating keeps it from melting from the warmth of your hand. Chocolate that has not been chilled softens on the grater, turns into a sticky mass, and clogs the holes.

How Should You Chop Chocolate with a Knife?
Starting at the edge of the chocolate block, draw a wide, heavy chef’s knife back and forth in a sawing motion. The knife’s own weight separates the piece; applying extra pressure can make the chocolate crack in unexpected places. If the blocks are thick, first split them into 2 halves and then cut them into thin slices for more even pieces. In a warm kitchen, the chocolate may soften and stick to the knife; if this happens, wiping the knife occasionally with warm water reduces sticking. In a cold kitchen, the block becomes too hard, and fine shards fly in every direction while cutting; that is why the ideal range is 18–20°C / 64–68°F. If a cake recipe calls for evenly chopped chocolate, marking the block with a ruler before cutting or aiming for even slices by eye makes a difference; uneven pieces heat at different rates as they melt, so some may burn while others remain solid.

Why Is Grating Difficult, and How Can You Make It Easier?
The biggest problem when grating is the heat transferred from your hand to the chocolate; as your fingers touch the block, its surface begins to melt and leaves a thin layer on the grater. In addition to chilling the block, wrapping it in a paper towel while holding it prevents the warmth of your hand from making direct contact. Use a grater with small holes for a fine, powdery texture and one with large holes for thick, curled shavings; if these 2 are confused, you will not get the texture you want. If you will not use the grated chocolate right away, keep it in a covered container in the refrigerator; if left out uncovered, it absorbs moisture and clumps.

Why Does Chopped Chocolate Sometimes Turn White?
Chocolate pieces held for a long time in a warm hand or left on a warm counter may develop a dull white coating as the fat on the surface separates and recrystallizes. This does not affect the flavor, only the appearance; melting and solidifying the chocolate again resolves the problem. Limiting how long your hand touches the chocolate while chopping is the most practical way to prevent this whitening. Transfer the pieces to a bowl right away and avoid handling them more than necessary.

How Should You Keep Chopping and Grating Tools Clean?
Chocolate residue becomes harder to scrape off once it dries on a knife or grater; wash the tools with warm water as soon as you finish, while the chocolate is still soft. Trying to wash them with cold water can cause hardened residue to get stuck in the holes and along the edges. If the same grater was just used for a salty or spiced ingredient, rinse it thoroughly between uses to keep the smell from transferring to the chocolate; otherwise, the grated chocolate may have an off flavor. Do not leave knives or graters with wooden handles soaking in water for a long time; the wood may absorb moisture and crack over time. Dry and air out these tools right after washing for better hygiene and a longer tool life.