Yeast Selection for Fermentation of Sugar and Grain
Fermentation and Yeast – What’s the Big Deal
Yeast is one of the most important components in your wash whether you’re making a Sugar Wash, Grain Wash, or Fruit Wash. Remember Yeast is the one’s converting sugar to alcohol in the fermentation process so without them there wouldn’t be any Alcohol. Yeast also has a major impact on the flavour of your final spirit. The aroma and flavour from whiskey, rum, gin, and moonshine arise during the fermentation process, and thus choosing that proper yeast and keeping them happy during fermentation will leave you with an end product that tastes better than any other store-bought spirit ever could.
How Does Yeast Make Alcohol?
Yeast cells consume sugars found in corn, barley, sugar, or fruit mash and produce carbon dioxide and alcohol as waste products. To relate think about you eating a hamburger and a glass of milk, 8 hours later what comes out is the equivalent to the carbon dioxide and alcohol the yeast extrudes. When you drink that ice cold beer, you’re essentially drinking 3 – 5% yeast piss lol. Sorry I just couldn’t resist. With Spirits, it’s more like 40 %
What basic conditions do yeast need to thrive?
Correct and Even Temperature – The Correct Temperature will depend on the yeast strain that you are using for Fermentation. Check the back of the packaging for the correct Temperature and try to keep it within that range through the fermentation. It is important to maintain the correct fermentation temperature because if the yeast gets too hot, they will become stressed and die too cold and fermentation will stall.
Proper pH – The pH of the mash should be between 4.0 and 4.5 before fermentation. This will limit the growth of lactic acid microorganisms during fermentation. If you’re fermenting with fruit that is naturally alkaline pH you must be acidified prior to fermentation. You can adjust the pH using fresh lemon or lactic acid for acidifying the mash.
Oxygen – Oxygen is an important component of the Fermentation process that many people don’t consider. Its presence is required at the beginning stages of the fermentation as Yeast needs oxygen to reproduce. When oxygen is absent the yeast will begin to produce alcohol and will cease to reproduce. You can aerate your wash by a string it vigorously or giving the carboy a good shake before adding the yeast.
Nutrients – Yeast is a living organism and therefore needs nutrients to survive they can’t simply survive on sugar alone. If you’re doing a grain wash with malted barley, rye, or wheat, geared to produce wash alcohol of 5-10% there will be enough nutrients present to keep your wash healthy. However, if you’re planning a sugar wash or a grain wash with an alcohol content higher than 10%, you should add fermentation nutrients to avoid any nasty smelling or tasting by-products that unhealthy yeast will produce.
What problems can arise when yeast are stressed?
If you’ve created a terrible tasting rum, whiskey, vodka, or moonshine in the past and can’t figure out why it turned out so bad. The reason could be “Stressed yeast”. When Yeast is stressed, they produce excessive amounts of chemical compounds and flavours that don’t taste very good these include:
Sulfur – Everyone knows that Sulfur gives a flavour of rotten eggs that nobody wants to sip on over ice. Sulfur naturally gets removed from your wash by CO2. The more vigorous the fermentation, the less sulfur will be present at the end of the fermentation. You can achieve a healthy wash by creating a Yeast starter which will help the yeast to rapidly reproduce initially. Keep the temperature steady and make sure there are plenty of nutrients. Copper is also great at removing sulfur so if the plan is to distil your wash you won’t need to worry about the sulfur.
Fuel Alcohols – If you’ve had a wicked hangover after drinking a bottle of Moonshine Fusel Alcohols are to blame. This group of chemical compounds have no distinctive aroma or taste but will give you a killer hangover. Fusel alcohols can be removed during the distillation process by cutting the tails. To learn more about his process, check out our Cutting tails procedure to keep the production of Fusel Alcohols to a minimum you should ferment your mash as close as possible to the recommended temperature and keep it as steady as possible.
Overly Dry – If there is a total lack of sweetness or taste in your wash, your yeast might have powered through the mash and eaten all of the good stuff themselves. Champagne yeast and distiller’s yeasts have a tendency to do this.
Overly Sweet – If fermentation stops and your wash is still very sweet you’ve probably ended up with a high concentration of non-fermentable sugars this could be caused by incorrect temperatures when making your mash in the case of a grain wash. If you are using a sugar wash you’ve either got a stalled fermentation generally caused by low temperatures or your yeast have died off due to high temperatures or lack of nutrients. The end result is the same, a low alcohol yield.
Phenols – Phenols produce a plastic/medicinal/Band-Aid taste to the wash. How can you stop the production of Phenols? Well, start off by not using chlorinated water. You should also make sure all equipment used in the fermentation process is properly sterilized and an airlock is used during fermentation. Wild yeast contamination can contribute to the presence of phenolic compounds, so a properly sterilized environment is key to reducing the production of Phenols.
Acetaldehyde – Has the smell of green apples and can also cause bad hangovers. How can you eliminate the production of Acetaldehyde? Acetaldehyde exists in high concentrations when the mash is not allowed to finish fermentation. So always allow it to finish up don’t be in a rush. They can also be produced when the wash is aerated in the late stages of fermentation or when it is allowed to sit for long periods of time after fermentation is finished. How can you Remove Acetaldehyde from your Moonshine? Acetaldehyde has a very low boiling temperature so it will all be stripped out of the final product.