There is often a debate about the need, use, and benefit of sulfites (or sulphites if you live in many other English speaking countries) when making hard cider or even wine. Using or not using them along with sorbates can be a cause for much debate. Therefore, I wanted to explore the reasons why you might or might not add sulfites and sorbates to your juice and hard cider and what they do and don’t do to your cider. The research that I have reviewed suggests the following.
- Sulfites and sorbates at levels used for food preservation will not kill common human pathogens.
- Human pathogens are reduced and eliminated by ethanol, acid, and iso-a-acids like those found in hops.
- Temperature has a large impact on pathogen growth and reduction.
- Sulfites can act as an antiseptic to some bacteria and can suppress some yeast reproduction.
- Sorbates can suppress yeast growth.
Let’s review why I make these claims but first, let’s review a few key fundamental points about sulfites and sorbates.
When hard cider and wine makers talk about adding sulfites to their product, they generally mean potassium metabisulfite or sodium metabisulfite. This is also known by the brand name Campden and can be spelled sulphite if your English is from England. Per Wikipedia, Campden gets its name from Chipping Campden, located in Gloucestershire, England. This is where the solution was developed in the 1920s by the Fruit and Vegetable Preserving Research Station located there. You can thank the Boots Company for creating the tablet form that is ubiquitous with the name Campden today. The tablet form can be either potassium metabisulfite or sodium metabisulfite but they are usually configured to provide a predefined (50 or 67) parts per million (ppm) of sulfur dioxide (SO2) when dissolved in 1 gallon of liquid. The SO2 is the goal, the sodium or potassium metabisulfite is the means to that goal. Sorbates can also be various compounds but hard cider and wine makers are usually talking about potassium sorbate. When you add potassium sorbate to your hard cider or wine, you are creating sorbic acid, which is the goal.
Another fundamental point that I believe is key to understand is the natural creation of sulfur dioxide (SO2) in the hard cider or wine making process. Yes, fermenting juice naturally creates SO2. How much is created depends on the yeast and the fruit. In an article published in the January/February 2009, Practical Winery & Vineyard Journal by Pat Henderson (3) , he states that it is usually about 10 ppm. However, Lalvin EC-1118 yeast is noted to produce as much as 50 ppm. What’s important to understand is that the fermentation process naturally creates some SO2, which means all cider and wine contain sulfites or SO2. Some countries require sulfites to be identified on a label and this can be why you find labels that say “Contains Sulfites” even when no sulfites were added. On the other hand, hard cider and wine will not normally create sorbates or sorbic acid.
Okay, so we know what sulfites and sorbates are and whether they naturally occur in your hard cider. The key question is what do they do. For hard cider and wine, they act as a preservative. Sulfites can be used as an antiseptic if the concentration is high enough and while some use that to sanitize equipment, you wouldn’t purposely add that level to your juice or hard cider. However, many books and recipes advocate for sulfite to be added to juice prior to adding yeast and both sulfite and sorbate to be added to hard cider before bottling. Do you fully appreciate what these recommendations are trying to accomplish? Let’s explore what you are doing in these two situations.
Adding sulfite to juice before fermenting.
Many hard cider recipes have you add a small amount of sulfite to your apple juice 24 hours before you add yeast. One argument could be to eliminate any human pathogens in your juice. By pathogens, I mean bacteria that could make humans sick, like E. coli, listeria, or salmonella. However, research conducted on apple juice with various preservative found that they didn’t eliminate or prevent the growth of common pathogens (1). It also indicated that just the acid found in apple juice isn’t always enough to kill all forms of some common pathogens. However, research on beer’s ability to kill these pathogens indicates that hard cider with an ABV above 2.5% would do the same or better given the pH is normally lower in hard cider (2). Hard ciders of normal pH (3.0-4.3) and alcohol (5.0-8.5% ABV) would naturally eliminate common human pathogens in the process of making it. Therefore, adding sulfites (or other preservatives) doesn’t help with pathogens control. What does it do?
Sulfites added to fresh juice suppress bacteria and some wild yeast found naturally in the juice unless the juice has been already been pasteurized. However, these naturally occurring organisms are how many hard cider producers in the world ferment their juice and have been fermenting it for centuries. These are not human pathogens but organisms that create alcohol and flavors in your hard cider. Note, I didn’t say kill. Sulfites can kill some bacteria but they are generally suppressing the reproduction of these organisms. They are also preventing oxidation. They do this by capturing the oxygen molecules and binding them as sulfur dioxide. I suggest reading Henderson (3) for more details on free and bound sulfites. For the purpose of this article, the main point is that you would add sulfites to your apple juice only if you are worried about the potential flavors you will create as part of the wild yeast and bacteria in your juice. Sulfites are providing you a clean slate from which you can build your hard cider. If you are worried about pathogens, you need to pasteurize or find different apples or juice because sulfites won’t protect you.
Adding sulfites and sorbates to hard cider before bottling.
Hard cider is neither beer nor wine but you find lots of people applying processes and ideas about one of both to the making of cider. Don’t get me wrong, there are a lot of good ideas and processes that work well on cider. However, I also believe this often creates misunderstanding about what they do for hard cider. Wine uses sulfites as a preservative to stabilize the wine and try to keep it from evolving further. It can prevent malolactic fermentation in a wine where it isn’t desirable. It can also help retain color by preventing oxidation. It’s main focus is to address potential bacteria spoilage and changes. Potassium sorbate is added for yeast and mold control.
Potassium sorbate added to wine or hard cider is used to suppress the reproduction of yeast and mold by creation of sorbic acid. It does not kill these organisms but prevents them from reproducing. This is why adding it to something already fermenting doesn’t stop the fermentation. Potassium sorbate is what allows you to back sweeten with sugar and avoid fermentation of those sugars. However, It can break down over time and if sulfites are not added along with the sorbates, some bacteria can break down the sorbates creating a geranium aroma. The addition of sulfites and sorbates together before bottling creates an environment that stabilizes a hard cider and prevents it from evolving. It also prevents yeasts and organisms from converting any sugar added after treatment from being fermented. This provides the ability to sweeten a hard cider. However, it means you can’t bottle condition the cider. It also creates a shelf life for the hard cider since the yeasts are not killed and the sorbic acid can be broken down with time.
Hard cider is generally considered a live and evolving drink. The longer it ages, the better it becomes. Some like to think of it as wine where the addition of sulfites and sorbates preserve it in its current state. However, that means it’s no longer evolving. This is where you really shouldn’t think of hard cider as wine or beer but hard cider. If you want it to stop it from evolving, adding sulfites and sorbates may be the right choice. However, if you feel it should be continually evolving then adding these may not be what you want. If you need a sweeter cider, you may want to add them to prevent the added sugar from fermenting in the near term or consider filtration or pasteurization. If you are trying to protect yourself from pathogens, you should probably find better fruit or use pasteurized juice.
Sulfites and sorbates may be perfectly fine and not cause any health issues. However, I wish to eat fresher foods with fewer preservatives in them. I think diet and exercise are key to a long and healthy life. For me, that diet should include fresher and more natural food and drinks. Whether you decide to use them or not, I hope this article has helped you better understand what they do, what they don’t do, and why you may or may not need to use them.
(1) Miller, L. G., and C. W. Kaspar. 1994. Escherichia coli O157:H7
acid tolerance and survival in apple cider. J. Food Prot. 57:460–464.
(2) Menz, G., Alfred, P., and Vriesekoop, F. 2011. Growth and Survival of Foodborne Pathogens in Beer. J. Food Prot. 74:1670-1675.
(3) Henderson, P., 2009. Sulfur Dioxide: Science behind this anti-microbial, anti-oxidant, wine additive. Prac. Winery & Vineyard Journal Jan/Feb 2009.
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