Fresh pressed apple and pear juice will naturally have the microflora (yeast and bacteria) to ferment into hard cider. For many people, they use these natural organisms to create great hard cider. For others, they want to control the flavors and process and will use commercial yeast. In both cases some people use Campden tablets, which is either sodium or potassium metabisulfite. When added, it becomes sulfur dioxide (SO2) that binds with many compounds to kill or suppress organism and various reactions. The details behind why you should or shouldn’t add metabisulfite and sorbate are covered in my other post on that topic. However, it is not uncommon for people to post or ask for help because there cider isn’t fermenting and the reason is often caused by the addition of Campden tables.
In simplistic terms, you crush up some Campden tablets and dissolve that in your juice. You wait 24 hours or more and add your yeast. The Campden as it dissolves becomes sulfur dioxide and either binds with compounds in your juice or floats freely around looking to bind with something. When it binds, it kills or suppresses the microflora in your juice and also prevents oxidation of tannins and other compounds. However, the amount of SO2 needed to do this is dependent on the pH of your juice. The more acidic your juice and the lower the pH, the more effective SO2 is at suppressing microflora. Think of the acid as an enabler.
The yeast and bacteria have a strong wall that protects it. Acid breaks down that wall and makes it more susceptible to attack. Just like SO2, acid can suppress microflora so when you combine these two, they can both gang up on the poor microflora and overwhelm it. Remember, this microflora is bacteria and yeast. While bacteria is more susceptible to SO2, yeast is as well. Also, commercial yeast is no different from the yeast found as part of your microflora. It is just wild/natural yeast that was harvested, isolated, and grown because someone liked its fermentation characteristics. Therefore, if you have a highly acidic juice (low pH) and you add Campden, you have the potential to create an environment that is inhospitable to not only your natural microflora but also your commercial yeast.
Many recipes and articles blindly include the use of Campden based on wine making processes that are proving somewhat dated. Unfortunately, this often leads to the most likely cause for posts and questions like “Help! My cider isn’t fermenting”. In my opinion, recipes shouldn’t include Campden unless they are going to explain how and why to use it. Apple and pear juice vary so much in acidity and other compounds that affect the dosage of Campden that is can be challenging to get it right. The impact of getting it wrong is your juice won’t ferment, is slow to ferment, or gets stuck while fermenting. While the impact of not including it at all is that you have a small chance that your cider will have a funky or unique flavor. By the way, the funky flavor is what many people are trying to achieve. Regardless, if you find yourself in a situation where you added Campden and now your juice isn’t fermenting, what do you do?
If you have accidentally added too much metabisulfite to your juice, you have a lot of free SO2 suspended and floating around looking for things to bind. You can think of it like CO2, and what’s the best way to remove CO2, degassing or agitation. The good thing is that the first stage of fermentation needs and loves oxygen. Yeast need it to reproduce. It’s only after fermentation ends that you want to restrict oxygen. Also, it’s almost impossible for a home cider maker to add too much oxygen to their juice. In a lab or a commercial cidery that has oxygenation equipment, you might be able to over oxygenate your juice but generally, this isn’t something you need to worry about. To remove the free CO2 so that you can add more yeast and start fermentation, you want to aerate and agitate your juice. Here are the most common methods.
- Splash Racking: If you have a large fermenter, you can rack your juice back and forth between containers while intentionally splashing and agitating it. Racking means to siphon or pump it back and forth between containers. Racking also helps if your juice has clarified and you want to take advantage of siphoning the clear juice off the sediment at the bottom.
- Pour Racking: If you have smaller fermenters, you can simply pour it back and forth between containers. Again, you are not worried about oxygen and in fact, the more the better.
- Shake Aeration: Another good option for smaller fermenters is shake aeration. Pour half the juice into another fermenter, cap and shake them aggressively. Ensure you have a good grip and it’s well sealed.
- Forced Aeration: For larger fermenters, you can aerate in place with a pump and diffusing stone, similar to force-carbonation devices but instead of CO2, you pump air through the juice.
All of these methods result in free SO2 being released and oxygen be added. That means that your juice will be more hospitable to yeast that you add. Instead of the free SO2 floating around and binding with the yeast you add, the yeast can finally absorb the oxygen and nutrients in the juice and begin the fermentation process. You do need to add more yeast and there is one more recommended action to take.
- Yeast Inoculation: If you added enough Campden to suppress fermentation, you need to inoculate your juice with more yeast. It’s also advisable to make sure the yeast is healthy and active before you add it. That means you should create a starter. Hydrate your yeast not only in water but include some sugar and nutrients and wait until the yeast is frothy and working before you add it to your juice.
Following these recommendations should result in the creation of that hard cider you wanted. Hopefully, it also helped you realize the importance of understanding your juice and the impact of adding metabisulfite. Like all things related to making hard cider, there are often no wrong or right methods. My main goal is to help you understand what decisions you are making so you make the best hard cider possible. I hope this helps and as always, let me know if you have questions.
Did you enjoy these tips on making hard cider? Check out my book to learn more ideas and information on making and enjoying hard cider. It will help you develop a process that matches your desire and equipment. It will also show you how to pair cider with food to maximize your experience. You can find it as an eBook and a 7×10 paperback on Amazon or a 7×10 paperback on Barnes & Noble. Click on these Links to check them out.