In episode 21 of Distilling Craft, we talk about sugar fermentations to wrap up the fermentation series we started last season, and we bring in Greg Eidam from Sugarlands Distilling Company in Gatlinburg, TN to talk about making sugar shine and how the rest of their process goes.
Everyone’s First Fermentation
Sugar fermentations are typically the first fermentation that is tried by anyone looking to make a little hooch. Unfortunately, since we don’t know much, they end up being very poor tasting either because we used too much sugar trying to crank up the ABV or we used too much nutrient and that caused the spirit to burn all the way down. Sugar is used because it is about the easiest thing to ferment since it is already in the raw form that the yeast need. About the only thing that comes close is the fermentation of fruit juice since it also is already in a usable form, but with sugar washes, you can control the concentration at the start to ensure you get the ABV that you are looking for. With fruit juice washes, you’re pretty much stuck with what nature gave you and every year can be different based on the growing conditions. With sugar washes, you get a lot more control. Since you are controlling the amount of sugar, you can design your washes to maximize your yeast’s production without causing off flavors and it is possible, though not advisable, to get 20% ABV washes from sugar fermentations. Maximizing the ABV of your ferments will decrease your labor and energy costs in the production of your spirit; you just also need to maintain good flavor while doing so. Also, as a feedstock, sugar can be utilized 100%, whereas, with any other stock, you will be paying for things you can’t convert to alcohol. That being said, sugar washes are generally not very flavorful because everything in them gets converted to alcohol, so we need to be careful because every off flavor stands out that much more against a plain background. Typically, pure sugar washes are headed to be either light rum or vodka and so yeast selection and ensuring that you maintain their ideal conditions become much more important. The first step in not over-stressing your yeast is to not overload them with sugar, this means 1.5 to 2 pound of sugar per gallon. When targeting higher ABV washes, start with the 1.5 to 2 pounds of sugar and then, once fermentation is halfway through, add 50% more sugar and don’t forget the nutrient to go with it, this way your overall sugar concentration stays the same and you don’t put too much osmotic pressure on the yeast. You can tell you’re halfway by watching the weight of your fermentation.
Photo provided by Sugarlands Distilling Co.
The Details About Sugar Fermentations
Since you’re keeping the sugar down, at least initially, you will get very fast fermentations with sugar. There are no longer chain sugars that need to be converted, so after your lag phase, you can have as short as 24-hour fermentations and even with keeping the temperature under control (which you should to prevent those off flavors), we’re only looking at 72-hours. The lag phase is dependent on pitch rate and I generally prefer a higher pitch rate so that fewers nutrients are needed in the wash, and your lag phase should be around 12-16 hours. Let’s take a quick side trip to talk about what the sugar that the yeast are eating really is. Sugar seems obvious since it’s ubiquitous, but even a common sugar like high-fructose corn syrup isn’t as simple as it seems since, due to the backlash against it, a whole new branch of sugar is being created. Corn Dextrose, corn glucose and now High Fructose corn syrup are being called corn sugar, though there is some pushback from the FDA on the issue because they are not chemically the same thing. The chemical makeup is very important with sugar though and that is why all refined white sugar is 99.95% pure sucrose. Even brown sugars are 96% sucrose so combining a dextrose with a fructose doesn’t make a lot of sense. The other side of this argument and the one that is relevant to us is that due to this purity, sugar can’t bring a lot to the table beside sugar. 0.1% is all that is available for flavor and, according to my local Beet Sugar Co-op, the rest is Sodium, Potassium, Calcium, Magnesium, Iron, and Phosphorous so not a lot of flavor but a few micronutrients for the yeast. Because of this minor difference, beet sugar is used widely in the professional sugar market; basically, any time that you see a product made with sugar and not specifically cane sugar, it’s probably made with beet sugar and in fact 60% of all sugar used in the US come from sugar beets. Most of the time the recipes are interchangeable between beet and cane, though I’ve been told that beet brow sugar cannot substitute for cane brown sugar. So, the 4% difference between them is too much. Where I’m going with this is that if you are going to be making a white sugar product and if you’re not specifically trying to make rum, then beet sugar can be a great alternative to cane sugar at a lower cost and lower trucking—depending on where you live. Particularly when you are making vodkas and flavored vodka, it can be a way to decrease your ingredient cost without changing the flavor of your spirit. Where the source of sugar really matters is with the TTB. If you’re using cane sugar you can also make rum; if you’re using corn sugar you can make whiskey, but if you’re using beet sugar you’re making a DSS or vodka. One kind of weird sugar I’ve been working with lately is coconut sugar, which is derived from the sap of a palm tree and, while several types of palms are used, the coconut palm is one of them so that’s what stuck for marketing reasons. I haven’t had a chance to distill it yet but that will be coming later this year, and this example just goes to show how many weird types of sugar are out there. Of course, I can’t forget sorghum which also makes a very fine granulated sugar and if you’re in that part of the country, can also make good vodka. There are some micronutrients available to your yeast in using a sugar wash but there aren’t very many, so we’re going to need to provide supplemental nutrients in order to help the yeast propagate and ensure they don’t produce off flavors. Generally, you can go three generations of yeast without nutrient before their daughter cells start showing major defects, which is why I was recommending increasing your pitch rate above. Though it’s probably cheaper to provide nutrient and pitch at lower rates, and if you’re doing multiple sugar additions you’ll have to add nutrient in each stage.
Photo provided by Sugarlands Distilling Co.
The most important nutrient for yeast is nitrogen, and there are several measurements used to determine how much nitrogen is in your wash. The easiest one is FAN (Free Amino Nitrogen), which measures the amount of amino acids and peptides and can be used by yeast. FAN can get combined with ammonia and ammonium for a different number YAN (Yeast Assimilable Nitrogen). In either case, the number basically means how much nitrogen is there for your yeast to consume. FAN is the easier of the two to measure and it makes up the majority of YAN, so really you just need your FAN number. There have been a bunch of studies of how much nitrogen is needed and generally, it looks like 150 mg/L is the minimum, while 200-250 mg/L is ideal. The higher the gravity of your wash the more nitrogen you’ll need, and Stone Brewing has done some studies showing that their high gravity IPA needs 316 mg/L of FAN. Of course, having enough Nitrogen is important but as with most things in life, too much is a bad thing. Excess Nitrogen can be lead to the production of diacetyl, isoamyl alcohol, propanol, and isobutanol— all of which lead to that sensation of burning while drinking spirits. It is possible to minimize these by taking good cuts, but why increase the work for yourself and just eliminate them in the fermentor. This excess nitrogen problem can appear in many spirits, especially those who have naturally high nitrogen to begin with, like molasses and all malt fermentations. In order to determine the amount of FAN, traditionally the Kjeldahl method was used but it was replaced by the Ninhydrin method, which is the preferred method for the American Society of Brewing Chemists. In order to do it, you’ll need a spectrophotometer, hot water bath, and several different reagents. If you have a full lab set up, this is the best way to go. For those who are lacking on their distillery lab or just don’t want to spend more time in there then they have to, there is another method called the NOPA Procedure that runs about $1.5-4 per test kit. These kits are self-contained and don’t need a large lab set up to make them work, though you will still need to be careful. I’d recommend using them as you are dialing in your recipe and then every time you get a new delivery of fermentable since the nitrogen content can change from batch to batch. There are other minerals and nutrients that your yeast need but they are best sourced, for sugar washes at least, from a commercial yeast nutrients. These will come with dosing instructions and you can ensure that you are getting all of the little things you need into your wash. Do be careful that you aren’t adding more nitrogen to your wash with these nutrients or if you are, that you account for that source when doing your separate nitrogen addition. There are other ways to bring these nutrients to the party and that is with adjuncts. Historically, this was the common way to do things. You would see a white sugar rum cut with molasses, which has tons of nutrients and minerals in it. In the modern era, corn sugar washes will have malt added to them and then of course, there is sugar shine where the corn addition brings the nitrogen and other nutrients that the yeast need. All of these methods also bring flavor to these fermentations which may not be best if you’re trying to made vodka. A first source of yeast nutrient can be dead yeast. Yeast are capable of cannibalization and the dead yeast that successfully completed a fermentation will already contain all of the nutrients needed for the next batch to be successfully fermented. If you are using this method, make sure to boil the yeast or pull them out of the bottom of your still so that they are dead and will not reactivate in your wash. Having already been through a fermentation they will be more stressed than your currently pitched yeast and can produce off flavors.
Meet The Guest
Sugarlands Distilling Company, located just outside the mountains in downtown Gatlinburg, Tenn., is a fully functioning distillery and entertainment venue. Guests may sample Sugarlands award-winning line of spirits, take behind-the-scenes tours of the still house, enjoy live regional music and enjoy hand-crafted cocktails at the Sugarlands Cocktail Kitchen.