Cyser Fermentation Problems

Home brewers know that apple cider is an incredible fermenter- it just wants to ferment. If you’ve ever had cider in your fridge develop a sharp flavor, congratulations, you’ve successfully fermented cider using wild yeast. So imagine my surprise when my cyser, which is cider and honey, failed to begin fermenting even when I added an aggressive commercial champagne yeast. Champagne yeast will ferment almost anything and are robust enough to handle even the most difficult conditions, such as cold temperatures, low nutrient levels and high alcohol levels. Even still, no fermentation!

Thinking out the possible causes for this problem, I thought that I had possibly mistakenly bought cider with preservatives in it. Sometimes orchards add potassium sorbate to their cider, which is a preservative that prevents mold and bacterial growth. It does not kill yeast and is not a poison or fungicide. Rather, potassium sorbate prevents yeast from multiplying. And since yeast need to be multiplying constantly to survive, potassium sorbate is a death sentence. Cider that is unpasteurized (which I don’t think you can even buy unless you know someone who owns a cider press) will start going hard immediately, as the apple skins tend to have lots of wild yeast. Most commercial cider is pasteurized, which means it is flash heated to kill bacteria and wild yeast. Even still, without potassium sorbate, this cider will still spontaneously ferment. Wild yeast in the air just love cider, and interestingly enough, (and unlike wine and beer) they will make a delicious hard cider. I’m not too sure why wild yeast works so well for cider but produce off flavors in beer and wine (except for traditional lambics, which are wild fermented), but it works! Anyway, I raced out to my recycle bin and the label clearly says “no preservatives”.
As I wasn’t coming up with any other answers, I emailed the Hudson Valley farm I bought the cider from to ask them, even though their label said no preservatives, it might be possible that potassium sorbate made it’s way into the cider. Perhaps the honey was making fermentation more difficult in a way I couldn’t understand, but cider is usually just so easy to ferment that I thought I would investigate the most likely causes first, namely potassium sorbate.

I got an immediate email response from the owner of Breezy Hill Orchard in Staatsburg, NY, and low and behold, the owner makes hard cider commercially and has studied hard cider making in England, which is the world-wide epicenter of hard cider (or as they call it, simply, cider). She told me she was an avowed anti-potassium sorbate advocate and never puts sorbate into her cider.

With the most likely culprit exonerated, I turned my attention to the next likely suspects. Namely fermentation temperature- the cyster must was in the low 70s, which is a good temperature for fermentation. Low temperatures can cause sluggish fermentations and can even send the yeast into dormancy, which could potentially explain fermentation failing to start. Very high sugar levels can also overwhelm even aggressive yeasts. Champagne yeasts can handle high alcohol and high sugar levels, but if the levels are too high too soon, they can shock the yeast into dormancy and fermentation may never begin. But that usually only happens with VERY high sugar levels.

Another reason yeast might go dormant is adding yeast too soon after sulfiting. Potassium metabisulfite is a winemaking chemical added right after the fruit is pressed. This chemical is similar to potassium sorbate in that it prevents yeast from multiplying, but it’s much weaker than sorbate and after about 24 hours (after all the other yeast has gone dormant) you can add commercial yeast and they will get a good start at fermenting the cider or wine. I don’t use sulfites because cider is already pasteurized to kill bacteria and as I detailed above, wild cider yeast doesn’t seem to harm the flavor of the cider. Plus the commercial yeast will almost instantly overwhelm the wild yeast and out-compete them for food. The wild yeast will simply not have the time to build up their populations before the commercial yeast takes over. Adding honey doesn’t change the thinking, as honey is naturally resistant to spoliation and will not contribute wild yeast or molds in any meaningful quantity.

The last culprit was nutrients. Beer, wine and cider all have more than enough nitrogen and other nutrients for a healthy fermentation. Honey on the other hand, natural as it is, tends to be only low levels of these nutrients. If you don’t add these missing nutrients, you’ll have a slow and painful fermentation. This isn’t just time consuming because when yeasts are stressed, they produce off flavors. Yikes. I thought the cider would add more than enough nutrients to the cyser to get the fermentation going. After all, even if there was enough nutrient to ferment the whole batch, there would at least be enough to get the fermentation started. Logically speaking, if there’s enough nutrient to ferment the cider, even if you add honey, there’s still enough nutrient to ferment the cider. Yet here we are.

I added a healthy amount of yeast nutrient to the cyser must about 40 hours into the fermentation. About 12 hours later the cyser was bubbling away. I still don’t understand how the nutrient could have been such a problem to prevent fermentation from even starting, but problem solved.

I bounced this off my new friend at Breezy Hill and she said she always uses nutrient when making cider and that in the olden days cider makers used to throw a leg of lamb into the cider to add nitrogen. They didn’t know what nitrogen was back then, in fact they didn’t even know what yeast was, but they saw that it led to a better fermentation and better cider.

I’ll be keeping an eye on this fermentation. More nutrient may be necessary to get the fermentation over the finish line!