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So I just fermented a 80 Shilling and thought I would try cold crashing for the first time. I dropped it from mid 60's to 38 or so in a 24 hour period and it sucked about 4 cups of sanitizer up the blow off tube and into my 5 gallon batch. The sanitizer was the usual dilution to half ounce per 5 gallons.

couple questions:

  1. Is the beer safe to drink?
  2. Can I re-pitch the yeast into another batch or is it damaged?
  3. How do you prevent suckback when cold crashing???

Edit: The sanitizer is StarSan.

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which sanitizer did you use? From the concentration, I'm guessing iodophor. – mdma Mar 9 '12 at 18:01
The sanitizer was StarSan – Patrick Kafka Mar 9 '12 at 20:40
What if it was Steramine that dropped in the beer? I wasn't thinking when I transferred my beer from the carboy to a container that had a spigot to make bottling easier, and the Steramine solutions in my rack and cane dropped into the beer. – Dave Apr 26 '15 at 6:20
up vote 9 down vote accepted

If the sanitizer was StarSan, then you'll be fine. At the usual concentration of 1oz per 5 gallons, it's safe - even safe enough to drink. StarSan is phosphoric acid and surfactants - coke is also largely phosphoric acid and sugar, so the two are in someways similar. In a radio program, Charlie Talley, 5 star chemicals allegedly drank a glass of starsan, and he mentions that the yeast can also feed on it. (The phosphoric acid disassociates and the yeast absorb the phosphorus.)

If it was iodophor, then it's only prudent to be concerned since iodine is toxic (to people and yeast) in high enough doses. However, after 24 hours most of the iodine will have degraded/evaporated. Was the solution still orange/brown color? I'm guessing not, and so you will be fine. But let's consider the worst case - that the solution was freshly made. 1/2oz iodophor to 5 gallons gives 12.5ppm. 4 cups (ca. 1 liter) contains 12.5mg of iodine, and that's what was added to the beer, so your 5 gallons of beer has 12.5mg of iodine in the whole batch. In a pint, that's 0.31mg of iodine.

So, how many pints of iodine beer can you drink in a day?

"Iodine is an essential component of the thyroid hormones that are involved in the regulation of various enzymes and metabolic processes. Thyroid iodine accumulation and turnover were used to set the Estimated Average Requirement. The Recommended Dietary Allowance (RDA) for adult men and women is 150 μg/day. The median intake of iodine from food in the United States is approximately 240 to 300 μg/day for men and 190 to 210 μg/day for women. The Tolerable Upper Intake Level (UL) for adults is 1,100 μg/day (1.1 mg/day), a value based on serum thyrotropin concentration in response to varying levels of ingested iodine." (p. 258)


If you only drank beer, and didn't eat anything else, then you could consume 3 pints and be below the tolerable upper intake level quoted there.

But keep in mind this is worst case scenario. Iodine is very volatile and will evaporate into the headspace of the fermentor.

The yeast will also be fine, although I would make a starter to proof the yeast and test viability, just to be sure.

To prevent this from happening in future, replace the blowoff tube - a regular airlock should be fine once the the vigor of primary fermentation is over.

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A 3-piece airlock will suffer from the same problem as the blow-off tube. The negative pressure created in the carboy as the beer cools will suck the liquid from the airlock into the beer, though less that 4 cups. I believe that a 1 piece airlock will not let any liquid into the beer while it cools. – Tobias Patton Mar 9 '12 at 18:50
That's partially true - depends upon how full the 3-piece is. I was unsure about this, so I just grabbed a 3-piece and tried it! The water comes out, but only when the airlock is full. Two things happen - the hat gets sucked down to the base, making it hard for any water to pass. Pushing the hat to the side, allows more water and air in. But, when the airlock is about 1/3 full, it's not possible to suck up any more water. Like you say, the same is true for the single piece airlock - under half full and you can't suck up the water. – mdma Mar 9 '12 at 19:01
thanks for the response. btw, it was StarSan. – Patrick Kafka Mar 9 '12 at 20:34
ok, then no danger at all. But Starsan should be made up to 1 oz per 5 gallons - you write 1/2 oz, which is too little to be effective, especially your water is hard. – mdma Mar 9 '12 at 20:36
@TobiasPatton - I just checked my airlocks - they all have markings, below which it's not possible to get any backdraw of liquid. Although I'm glad you mentioned it, since I'd assumed they were overflow markings, not underflow markings. – mdma Mar 9 '12 at 23:21

I use gin as it is fine to drink if you accidentally suck it back through the airlock.

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