National Cinnamon Raisin Bread Day

What the day is

National Cinnamon Raisin Bread Day is observed on September 16. The loaf is a good example of ingredients that fight the dough they are in.

Origin and background

Cinnamon is antimicrobial. The compound responsible for most of its flavor, cinnamaldehyde, inhibits the growth of bacteria and fungi, and yeast is a fungus. Mixed thoroughly through a dough in quantity, cinnamon measurably slows fermentation, giving a sluggish rise and a denser loaf. This is the practical reason the classic version is made by rolling the spice into a sheet of dough as a swirl rather than blending it in: the yeast is largely kept away from it, and the flavor is concentrated where you meet it.

Raisins cause a different problem. A raisin is a concentrated sugar solution with very little free water, so placed against wet dough it pulls moisture out of its surroundings by osmosis, drying the crumb immediately around it. Soaking raisins before they go in, then draining them well, loads them with water first so they take nothing from the dough. Dry raisins also scorch at the crust, because their surface sugars burn long before the loaf is baked through.

The famous fault of this bread is the hollow tunnel that opens under the swirl. It happens because a layer of dry sugar and cinnamon between two sheets of dough never hydrates into anything and never bonds, so it acts as a slip plane and the layers separate as the loaf expands. The remedies are consistent: brush the sheet with water or egg first, use a paste rather than loose powder, roll it up tightly with no trapped air, and do not overfill.

The enriched dough involved is the same category as the hot cross bun covered in another entry, and rises slowly for the same reason.

How to take part

• Soak the raisins and drain them properly before adding.
• Swirl the cinnamon in, rather than mixing it through the dough.
• Dampen the sheet before rolling to stop the tunnel forming.
• Roll it tight, without trapping air at the seam.
• Toast a slice, where the sugar in the swirl caramelizes properly.