Usually, my answer to a question about hard cider is “it depends”. I generally try not to be definitive because there are simply so many unknown factors that being definitive is almost always wrong. However, for this article, I’m going to argue a definitive. The definitive is that you should not use Campden tables in your apple juice before fermentation. In other words, stop killing your juice. For reference, Campden is a brand name for sodium or potassium metabisulfite, sulfite, suliphite, and metabisulphite. My arguments will also hold for pasteurizing your juice if you are fermenting it. If you are drinking it fresh, there are different considerations, but for juice that is being fermented into hard cider, stop killing it!
Basically, Campden or potassium metabisulfite converts into sulfur dioxide (SO2) when added to your apple juice and provides preservative capabilities. For more details on what they do and don’t do, check out my earlier post on sulfites and sorbates. As I noted in that article, sulfites don’t do anything to protect your juice or prevent you from getting sick and that argument for pasteurization doesn’t hold for fermented juice either because hard cider is capable of naturally killing off those pathogens. Campden and pasteurization can also impact the potential benefits to probiotic gut health. However, for now, let’s just explore the impact to fermentation. For this article, I am going to layout the research I’ve done on why you should avoid killing your apple juice before fermentation by adding Campden (or pasteurizing). I am going to do this by reviewing what are commonly held beliefs and arguing why they are wrong. If I miss something, leave me a comment.
Belief #1: The recipe, book, or friend told me to treat my juice with Campden before adding yeast.
If you are adding Campden to your apple juice because someone said you should, stop. This is the first indication that you should stop killing your juice. Campden, or potassium metabisulfite, is pH sensitive and the pH of apple juice is always changing. There is not an average treatment that works for all juice. Use of Campden requires you to know your pH or you risk adding too much and having fermentation issues. If you are not measuring your pH, you should not be adding Campden.
However, if you are measuring your pH and you know the proper amount of Campden to add, do you understand why you are adding it? If a recipe or book said to add it, did they explain why it’s important and what it does? It kills and suppresses the natural micro flora in your juice. These are wild yeasts and bacteria. Yes, some of those yeast and bacteria could produce aromas and flavors that are not desirable. But you can’t simply isolate the bad actors from those that produce good flavors. Also, there is the benefit of the many over the few. One of the common themes that I run across in my research is that you can’t judge aroma individually. What smells like rotten flesh in an isolated laboratory experiment, may make a hard cider smell perfect when combined with the other 20-30 aromas created in a natural fermentation. The whole works to create complexity and that complexity is often appreciated by the consumer. So, if you are adding things because something says to do it that way, stop doing that. My recipes include pectic enzyme but if you haven’t read my articles on pectic enzyme or juice clarity, you shouldn’t add it. It is often stated that everything you need to make hard cider in contained in the apple. If you are adding something to that process, understand why before you add it.
Belief #2: I want to kill off all the bad natural micro flora so my inoculated yeast can work freely.
I recognize that the natural micro flora in your juice will not always create the perfect hard cider. Yes, there is the risk that you might get undesirable results if you allow the natural micro flora to run wild. If you are like me and want the perception of more control, you can inoculate with yeast. This might lead you to think that you should therefore “kill your juice” so it doesn’t interfere with your inoculated strain. I have good news. Inoculating with yeast will overwhelm the natural micro flora by first robbing it of nutrients(1) and then through the creation of ethanol(2). The instruction yeast providers give when using their yeast strains ensure you will literally have an overwhelming amount of yeast that is also healthy and ready to start working. Natural micro flora takes time to build its colony and while some work faster than others, none of them work as fast as an inoculated yeast. This is why there are multiple phases in a natural fermentation(3). It takes time to build the various colonies.
Saccharomyces cerevisiae will naturally dominate a wild ferment. In warm temperatures, it can be hours where it might take up to 3 days in cold temperatures. However, cold temperatures suppress all activity. Apple juice/must is initially dominated by Hanseniaspora and Kloeckera type yeast and it takes a few days for the smaller saccharomyces yeast population to become dominant. If you want to eliminate these “wild” yeast, you don’t need to add sulfites. Just help nature along by inoculating with a large colony of commercial yeasts. This eliminates the first phase of a natural/wild ferment, which is where the saccharomyces population grows. By inoculating, the yeast immediately begin robbing the natural/wild Hanseniaspora and Kloeckera yeast of nutrients and kills off these types of yeast as well as many bacteria with the production of ethanol. What is left are strains that you may actually want. These are the lactic acid bacteria (LAB) strains that can perform malolactic fermentation (MLF). Note, there are potential spoilage bacteria and yeast remaining that are more resilient. These are the hardy acetic acid bacteria and Brettanomyces strains of yeast. However, these can be controlled through other means, one of which is the use of Campden or pasteurization. But, my point is that you don’t need the Campden pre-fermentation. Post-fermentation additional are for another discussion, which goes back to the debate about probiotic gut health.
(1) G. Specht and D. Delteil, Yeast Fermentation in Wine, Chapter 3, 3.14 Is it important to inoculate the grape with yeast before a cold soak with Pinot Noir?, Woodhead Publishing, 2010.
(2) Menz, G., Alfred, P., and Vriesekoop, F. 2011. Growth and Survival of Foodborne Pathogens in Beer. J. Food Prot. 74:1670-1675
(3) W.F. Morrissey, B. Davenport, A. Querol and A.D.W. Dobson, The role of indigenous yeasts in traditional Irish cider fermentations, Journal of Applied Microbiology 2004, 97, 647–655
Belief #3: I will add just a little Campden to kill off the bad stuff so only the good micro flora work.
Are there really bad types of micro flora? For example, are acetic acid bacteria that create acetic acid considered bad? If you are making hard cider, you don’t really want vinegar, which is what acetic acid is. However, small amounts of acetic acid can actually create a positive flavor profile in hard cider. Also, it is easily controlled by limiting oxygen and is one of the more resilient bacteria in your micro flora. What about Brettanomyces? You can actually buy cultured Brettanomyces yeast for fermenting to encourage sour and farmhouse aromas. This is like asking if nitrogen in your juice is bad or pyruvic and succinic acid. Too much of anything is probably bad. However, some of these items can add positive characteristics. The other aspect is whether the Campden or potassium metabisulfite you add can actually kill or suppress the all the natural micro flora. It will kill and suppress some of these but you have to add so much to actually kill off everything you probably wouldn’t want to drink it. The belief that you can kill the bad and leave the good is nebulous at best and wishful at worse. What you do is kill the most sensitive and leave the more robust.
Are the sensitive yeasts and bacteria the bad ones? Actually, they are some of the yeasts that might be most interesting for hard cider. For example, alternative yeasts can leave residual sweetness and create unique aromas. However, they are often more susceptible to Campden and the sulfur dioxide (SO2) it creates. This is why they tend to leave more residual sugar. They are not as efficient at producing ethanol as saccharomyces cerevisiae yeast, which means they use up all the nutrients but don’t produce as much alcohol. Also, the ethanol they do produce along with acid and other compounds kills them off faster. If your goal is to kill off these less hardy yeast and bacteria, I would suggest you just inoculate with a large yeast colony and let it do it’s thing. If you are wanting a wild yeast, I would just let the natural micro flora work its magic. This also gives you more options if you want to try for Malolactic Fermentation or improved maturation process post fermentation. There is a natural competition occurring in the micro flora, some even have killer characteristic. However, it’s this competition that can create the complexity many are seeking in their hard cider.
Ultimately, if you are adding just a little Campden or potassium metabisulfite, why? Either embrace the complexity of a wild ferment or inoculate for consistency. Leave the Campden for if you want to stabilize your hard cider. However, you know my article on that topic is going to cover probiotic gut health and the reasons you might not want to add it post-fermentation. However, I have more research to do before I’m ready to write that one.
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