One of the defining characteristics of bagels is that differentiates them from other forms of bread is that they are boiled prior to making. This poaching liquid is usually alkaline. Historically, the strong base sodium hydroxide (lye) was used, though most home cooks rely on the milder sodium bicarbonate (baking soda) because it is more readily available. Both will help to develop the surface sugars that create a brown crust, but I’ve found that lye-poaching yields more flavor and a crust allows toppings to adhere better.
My current bagel recipe and cooking strategy is based off of that from Peter Reinhart’s The Bread Baker’s Apprentice, except that I use a 0.5% (25g/5L) lye solution instead of baking soda. In Artisan Breads Every Day, Reinhart takes a different strategy to the preparation and cooking of the bagels, including use a more complex poaching solution that includes baking soda, malt, and salt.
For the last batch of bagels I made, I poached half in 5L of my usual lye solution, then added 3 tablespoons of barley malt syrup and 2 teaspoons of salt. The solution quickly turned dark brown and then a murky black. I was a bit apprehensive, but went ahead and prepared the second half of the bagels. On the left in the image below, you can see that the bagels poached in the malt-based poach came out considerably darker prior to baking.
I baked both trays at 500 °F for 5 minutes, swapped and rotated the trays, then reduced the temperature to 450 °F for 6 more minutes. I was expecting two sets of drastically different bagels, but aside from a slightly warmer hue for the malt-poached bagels, they looked almost indistinguishable.
The taste? Even knowing which bagels were which in advance, I found the malt added only a subtle sweetness to the crust which the traditional approach lacked. There was no obvious difference in texture. My sense going forward is that it’s not really worth it to add the malt and salt, and that the alkaline bath alone is all that’s needed.