Defeating potassium sorbate, pt 1

It’s fall season here in Toronto and grocery stores are carrying delicious, high grade apple cider that is seasonally pressed at local Ontario farms. I wait every year for the stuff and this time I was determined to brew some delicious hard cider.

So I was extremely distraught to find out they use my nemisis, potassium sorbate, to keep the stuff fresh.

Potassium sorbate is yeast killer. It stops fermentation dead in its tracks. It is a most powerful foe. There’s no way you can ferment around it.

Or is there?

After reading around online I came up with two possible approaches to defeating potassium sorbate (and similarly, sorbic acid). Both approaches are only proof of concept and my experiments are not scientific, however this is a good starting point to figure out which process I want to explore further.

Approach #1 was to overcome the potassium sorbate by bombing it with yeast. I poured one gallon of apple cider into an airlocked jug. Every eight hours I added 1 tsp of bread yeast (Lalvin 1118 too expensive, and unnecessary) over the course of two days, for a total six different doses of yeast.

The first three or four doses of yeast did nothing. The cider absorbed them completely. The last two doses, however, did kick off a gentle fermentation. Over the course of one week I observed a decrease in specific gravity from 1.050 to roughly 1.025. So conceptually this approach could work although it would require more yeast.

This is however a significant problem. There’s already 30g of yeast floating around in one gallon of cider, the liquid is cloudy, distinctly yellow and tastes horribly of yeast. Ultimately I wasn’t even able to drink through a small glass of the stuff. So I will consider this approach not useable.

Approach #2 was to kick off fermentation in a starter solution that does not contain any potassium sorbate, then add this to the main batch once the yeast is highly active. This was a technique I read about on fermentarium in a wonderful article titled Everything You Know About Potassium Sorbate Is Wrong. I decided to attempt this myself, with modifications.

First thing I tried was to ferment the batch with sediment from a previous batch of apple cider. Usually this works just fine. In this case, no dice. The potassium sorbate swallowed the sediment and killed it instantly.

So next I tried a process similar to the article. In a separate container, I pitched 5g of bread yeast into 250 mL of cheap apple juice. I waited 12 hours until the fermentation kicked into high gear. Then I poured this solution back into the main batch of cider.

This was enough to kick off a gentle, but consistent fermentation. Within four days the specific gravity had dropped from 1.050 to 1.030, which is not as fast as I’d like but still fast enough.

The next step in this project is to run a different experiment, with more controlled variables, to measure the effect of starter time, temperature and yeast concentration. I’d like to see if doubling the yeast dosage + allowing the starter 24 hours to kick off will result in stronger fermentation. More soon!

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4 Comments

  1. Posted November 19, 2010 at 10:51 pm | Permalink

    I’m looking forward to seeing your results. I’ve stayed away from making hard cider because I didn’t want to go through all the scenarios to see what would work until I had a better plan. Maybe I’ll be able to do some cider next year!

  2. Mark
    Posted November 19, 2010 at 11:10 pm | Permalink

    Kelly I’ve actually found cider is one of the easiest things to make. Even the cheapest apple juice will ferment easily and taste great. Potassium sorbate is only really used in super fresh high grade ciders — everything else uses weak preservatives like acsorbic acid which you can easily beat. Good luck!

  3. Phil
    Posted November 24, 2010 at 4:23 am | Permalink

    Hello Mark,
    Saw you at nerd night at the firkin pub.

    If you want a cheap source for EC1118 – go to Esperia on Warden, one bus stop north of the subway station. They sell EC1118 sachets for 50 cents which is cheaper than bread yeast.

    Asorbic acid is Vit C – Lovely stuff and no threat to yeast.

    The reason they chuck chemicals in is not because they’re buggers, but because apple skins are covered in yeast and they want to preserve that fresh pressed taste. Why the blue blazes do they not pasteurize it. Well, that’s the cheap easy option. If you’ve bought loblaws fresh pressed sweet apple cider (on sale at time of writing) then you know you can make a kick ass cider out of it. That stuff’s pasteurized. However, apples don’t work well under heat, in fact they cook. The PC stuff, has a slight apple pie-ness about it.

    Not bad, just not cider. That’s why the orchards sorbate or sulphite their stuff. If you get to them at the right time, at pressing time, they’ll give you apple juice happily without sullying it with heat or chemicals. You can drink it right away, or leave it a few days and it’ll ferment by itself!!! for free!! no EC1118 or fleischman’s in sight.

    So apple skins are covered in yeast. If you want free cider yeast., buy some organic apples, fill some sanitized 2L pop bottles with apple juice and grate the apple peel into those bottles. Loosen the lid to let gas escape. The bottles that do not grow mould, smell and taste lovely, will have a lovely deposit of genuine cider yeast at the bottom.

    Phil

  4. Mark
    Posted November 30, 2010 at 7:06 pm | Permalink

    Thanks Phil! I actually get my EC-1118 at Macedo Wine Juice (30 Ossington Ave). It’s also 50 cents a pack there, but much closer to where I live.

    I totally understand why they add the chemicals — the stuff is meant to be consumed, not bootlegged. You’re right that buying the cider fresh from an apple farm is the best route. However I don’t have a car, and trying to break chemicals is fun 🙂

    The PC Sweet Pressed Apple Cider is brilliant for fermenting. Tastes great and no heavy preservatives, plus it’s available year round. I recently made a batch where I mulled the cider with cinnamon, nutmeg, cloves and maple syrup before fermenting. Needless to say it was absolutely delicious!

    That’s an amazing idea using apple peels for starter, thank you! I will definitely try that in a future batch. Probably easiest to wait until summer when 30C heat will kick it off quickly.

    Thanks again for coming out to Nerd Nite, hope you enjoyed it!

    Mark

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