When I was younger, I had a strange obsession with baking. I would convince my parents to use their hard earned money to buy expensive ingredients. I would make cookies, pies, brownies, and I even tried bagels, which I would then sell at the fair for a paltry couple of dollars. My enterprise was all profit and I had no operational costs. Business was good. One thing I learned from my mass production of confectionaries was that what differentiates basic baked goods is essentially just the ratio of flour, sugar, eggs, and butter. More butter for brownies, less sugar for bread, easy. My next big discovery happened when I would run out of sugar and I either needed to put sugar on the grocery list or improvise. Since my parents usually travelled to the grocery store approximately once a week and my anxious fair-goers couldn’t wait that long, I would improvise more than not. Powdered sugar? Sure! Brown sugar? Why not? Black tar molasses? Now were pushing it...
Through all my substitutions and experimentations, I never got a single complaint. My baked goods were generally the same sweetness and the flavor was pretty constant. When cooked in with butter, chocolate, and what have you, people aren’t too pick about what sugar you use (at least not my fair-going Guinea Pigs). However, yeast does not share this indiscretion. In the next few paragraphs I will explain what differentiates sugar from a flavor prospective and how different sugars affect fermentation. I will try to keep science to a bare minimum.
Maillard Reactions (my-YAR, not like the duck)
Sugar beats are beige, sugarcane is yellowy green to red, cane juice is pale green, and molasses, a normal by product of sugar production, is… black. Hmm, seems strange. While some of this phenomena can be explained by caramelization, which is the breakdown (oxidation) of sugar through simply adding heat, the main culprit that produces the rich and almost savory tar is Maillard Reactions. Table sugar (sucrose) is produced by juicing beets and sugarcane and boiling off the water. The more pure sugar is extracted from the boiling mass early, before the heat has time to get some serious chemical reactions in. The second and third batch has been transformed from the heat into a completely different product. Ever wonder why cooked chicken smells so much better than raw or why seared tofu and mushrooms can taste meaty? Yep, that’s because of Maillard Reactions. It turns out, if you add heat, sugar, protein, and some moisture together, you can come up with some awesome smells and even better tastes. So show some respect to the next person you see milling about by the barbecue while consuming large amounts of beer and trying desperately not to burn the house down. After all, they are conducting science!
These Maillard Reactions and caramelization reactions create vastly different flavors that when disguised by a heaping portion of butter might not be recognizable, but when added to a very light combination of tea, water, and a S.C.O.B.Y. can be transformative (i.e. Kombucha).
In general, darker sugars (those that have undergone more Maillard and caramelization reactions) can contribute a range of caramel, nut, toffee, roasted, burnt, smokey, umami, and bread-like characters, among many others. Here is a ranking of sugar from least “character” to most:
- Granulated, powdered, pearl, confectioners sugar - different particle sizes and thus different rate of dissolving, however, these are all usually 99% sucrose and have little other contribution except simply adding sweetness
- Cane sugar - very similar to granulated sugar, but slightly darker
- Demerara sugar - slightly less refined and more toffee character
- Turbinado sugar - noticeably darker than Demerara and a bit more caramel character
- Light brown sugar - this can range in molasses character because it is granulated sugar with molasses added in various ratios
- Dark brown sugar - same process as light brown sugar, with more molasses added in
- Muscovado sugar - very dark and moist due to high amount of molasses with an extremely complex character (a little goes a long way)
Fermentability of Sugars
Here is where things get a little more science-y. Yeast and other microorganisms have many different enzymes and transport proteins to convert sugar into energy. Simple sugar is a broad term that describes monosaccharides (glucose, sucrose, galactose, etc) and disaccharides (sucrose, maltose, lactose, etc). Some types of simple sugars require much more work for the yeast to digest than others. It’s all very complex, but the take home message is that yeast is lazy. When given a choice between un-shelled pistachios and candy bars, yeast is going to go to town on the candy bars and then maybe shell a few pistachios if it absolutely has to. I blame poor parenting. A particularly noteworthy disaccharide that is easy to acquire and hard for yeast to digest is lactose (milk sugar). In other words, if you would like a Kombucha that finishes a bit sweeter, pick up some lactose and do some experiments.
Warning- if you are lactose intolerant (like me), do not consume ferments sweetened by lactose unless you feel like punishing yourself.
Here are the main points and how they will influence fermentation:
- Darker sugars will provide roasted, caramel character to foods and fermentations. Additionally, the darker the sugar, the harder it is for yeast to ferment, so the sweeter the final product will be.
- Your fermentation will change drastically with the type of sugar you use. If you want a dry finish, use a more fermentable sugar and if you want a sweeter finish, use sugars that are less fermentable. Here is a list of simple sugars from most fermentable to least:
- Sucrose - table sugar
- Glucose - fruit, honey, invert sugar
- Fructose - fruit
- Lactose - milk
That’s all for sugar. Variety is the spice of life. It is surprising how a little note of caramel can push a good ferment into a great one. Happy fermentations!
- Kunze, Wolfgang. (2014) Technology: Brewing and Malting. VLB Berlin.
- Amot, Stephanie. (2011) Fermentation of Various Sugars in Baker's Yeast.