In this episode, we talk about different sources of sugar and how they change between different fermentation base materials. Ryan Hembree from Skip Rock Distillers is the interview and we discuss how they make their variety of products.
This was episode one in a series that we’ll be doing exploring how different fermentation bases affect the process of making and fermenting your wash. Fermentation is really about the transformation of simple sugars into ethanol, or at least the type of fermentation we care about. The job of mashing, simply put, it is transforming start into the simple sugars that yeast can convert. There are very generally speaking three types of simple sugars; Glucose, Dextrose, and Fructose. These simple sugars get combined to form more complex simple sugars like sucrose and maltose. From there these building blocks can get combined to form long complex starch chains.
Different yeast prefers different forms of simple sugar. In some cases, like we talked about in our yeast episode that form is lactose but for the yeast that are common in our industry, they prefer their sugars as glucose and dextrose. Fructose is also a simple sugar though one slightly less preferred than the first two. Fructose and glucose combine to form sucrose which is also known as common table sugar.
The most basic processing for fermentation is done by using sugar directly. These are the fermentation of either sugar directly, molasses, honey or maple syrup. While except for white table sugar they all have more complex sugar chains as well they primarily have lots of sucrose. The sucrose does require some treatment in order to be readily consumable and that treatment is called inversion which is basically the process of breaking it down into glucose and fructose. When you get your reports on fermentable sugars this is basically what the sugars from invert section means.
One of the nice things about yeast is that they are adaptable to many different food sources and they don’t have to be fed straight glucose. The way that they are able to handle this is that they primarily look for certain molecules to meet their needs, oxygen, and glucose being two easy ones but then once there isn’t enough of that in their environment they will change their biologic processes to either create it in the case of glucose or so that they don’t need it in the case of oxygen. For glucose, they will actually begin emitting enzymes that will break down more complex sugar molecules and yeast are even capable of breaking down long complex carbohydrates as well if given enough time. Of course, that takes time and typically it’s time we’d rather have them converting that sucrose into ethanol.
This is helpful when we start talking about honey where there are some very complex sugars present but also lots of simple sugars. The yeast will start on the easy stuff and then begin converting over the longer chains. The real problem with fermenting honey is the concentration of the sugar since honey is typically 75% simple sugars it needs to be diluted considerably before it is capable of supporting yeast and then takes longer fermentations to convert all of the sugar present.
Molasses is created as a byproduct of the sugar creation process and the cane juice is boiled in order to get the sucrose to drop out. While this is happening we’ll also get some evaporation while both sugar is created and the relative sugar concentration in the juice goes up. The juice that they can’t remove more easy sugar from is molasses from there additional processing can be done to remove more sugar and the higher the processing amount the less sugar and the more by-products and you start getting the different grades. One of the processing methods I know well is for beet molasses and it is the Steffans process where the molasses is passed through a bed of resin containing various ions including Sulphur and the Sulphur is exchanged for the sugars. Undergoing this process makes the molasses only good for animal feed. Molasses in nice because not only does it typically have 50% sugar content the remaining mix is mostly nitrogen and other micronutrients for the yeast along with ash. The ash can be toxic for yeast in high concentrations so when you are using molasses with higher ash content (blackstrap) you won’t be able to use as high of a concentration as you would with a fancy molasses that had a lower concentration. The good news is that high amount of nutrients means that molasses fermentations typically need no supplemental nutrition, unlike white sugar and honey.
The other easy and common source of the monosaccharide sugars is from fruits, which are high in fructose. The nice thing about fructose is that it is perceived as the sweetest to the human brain this is great when you bite into an apple and it tastes sweet even though it only has a 7% fructose concentration and about 5% other sugars. The downside is that fruits that taste the sweetest don’t necessarily have that much sugar in them. The really good news is that, in theory, you could use less high fructose corn syrup to make things taste reasonably sweet. Of course, perceived sweetness has nothing to do with fermentation. Fruit juices are readily fermentable because their primary sugar doesn’t need to be converted before its converted. All you need to do for most fruit juice is ensure there is enough nutrients since aside from grapes the must tends to be low in nitrogen. While talking about fructose it is a good time to mention agave syrups which are the highest natural concentration of fructose and can be around 90% where even high fructose corn syrup is 55%
Grain on the other hand needs the most help in order to be converted into a usable form. In the life cycle of most grains the kernels are initially filled with sugar and then as the plant ripens that sugar is converted to starch. This is why the tip of an ear of field corn will be sweet even if it won’t be by the time it’s picked. Our job is to undo this process and that where mashing comes in. Mashing is not truly required since the grains themselves contain enzymes that are capable of converting that starch back to sugar so that the kernels can use that sugar to start growing a new plant. Not every type of grain has the same amount of intrinsic enzyme content which we can measure with a diastatic index. Grains like barley have a high diastatic index have extra enzymes that will not only convert their own starch but have the power to work on the starch from other grains around them. While these enzymes are always present they are most easily unlocked in the malting process that germinates the seeds and get them to start converting their own starch. The two main enzymes that are contained are alpha and beta amylase and these two work together to process the starch back into simple sugars. Alpha’s main job is breaking the long starch molecules in the middle while the beta snips the ends of chains to create maltose. Beta is the one doing the job we need but since it only accesses the end it works much slower by itself then if the alpha is able to open up more ends by splitting the longer chains. This is one reason is good to do you alpha rests before the beta, though that’s not always true. The alpha activation temperature does have some overlap with the beta range and so they are sometimes carried out together as a single rest. The most common sources for the amylase enzymes are from malted barley, malted wheat and malted oats. There is also the option of purchasing them directly if you want to use a single grain that has a diastatic index. The maltose that is created is a disaccharide that is made up of two glucose molecules.
The mashing of starches is the most common way to convert their sugar over and this process works whether we’re using ancient grains like quinoa, sorghum or buckwheat. Which aren’t true grains that can be made to be used to make whiskey but they are very similar though sorghum can also be processed to release sugar directly so it’s a bit of an odd duck. It also works on potatoes, sweet potatoes (high diastatic index!) and rice. There are some other methods available though. One common one found in the manufacture of sake is using a mold to do the conversion. The mold used is called Aspergillus Oryzae or better known as the koji. By allowing the rice to mold the starch is converted as well as make soy sauce, and convert over soybeans and potatoes.
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Mentioned in this Episode:
Skip Rock Distillers in Shohomish, WA: www.skiprockdistillers.com
Check out other episodes of the Distilling Craft Podcast here.
