Quick Question

[Ck27]

So, I had some fresh passion fruit and I pasteurized then added it to the beer but found out that the skin and rind can contain some levels of cyanide forming compounds. I just cut them up and added them basically whole to the beer. Is that okay? I just haven't brewed many fruit based beers and have been worried about it.

[Oginme]

The peels of passionfruit (P. edulis) does contain the cyanide precursors Cyanogenic Glycoside.  The amount varies quite a bit from cultivar to cultivar.  If you take the worst case scenario of P. edulis f.flavicarpa, this dosage amounts to an average of 287 mg/kg of peel.  Not being sure how much you put into your beer, you can figure on the weight of a passionfruit to be on the order of about 50 g max. the skin comprises less than 10% of the weight.  So if you have 10 passionfruits added to 5 gallons of beer, you would have added about 50 grams of the skin, which would result in about 14.35 mg of Cyanogenic glucoside in your 5 gallon batch.  The resultant concentration of Cyanogenic glucosyde would be approximately 0.76 mg/L at the most.  A blood level of 0.5 to 1.0 mg/L is considered mild exposure. Mild exposure manifests in general weakness, lowered blood pressure, light headedness.  A standard 12 oz pour or bottle would represent a dosage of around 27 mg. 

I could not find a good reference source on the bioavailability of Cyanogenic glycoside nor the rate of degradation to Cyanide in the body.  Nor could I find any reference in a short time to the rate of elimination from the blood stream of Cyanide. 

Not knowing how much you actually added to your batch, it would be impossible to say it is OK or not.  It is certainly a risk that you need to evaluate for yourself.  Honestly if it were me, I would dump the sucker and start over again.  Chalk it up to the cost of learning.

[Ck27]

The peels of passionfruit (P. edulis) does contain the cyanide precursors Cyanogenic Glycoside.  The amount varies quite a bit from cultivar to cultivar.  If you take the worst case scenario of P. edulis f.flavicarpa, this dosage amounts to an average of 287 mg/kg of peel.  Not being sure how much you put into your beer, you can figure on the weight of a passionfruit to be on the order of about 50 g max. the skin comprises less than 10% of the weight.  So if you have 10 passionfruits added to 5 gallons of beer, you would have added about 50 grams of the skin, which would result in about 14.35 mg of Cyanogenic glucoside in your 5 gallon batch.  The resultant concentration of Cyanogenic glucosyde would be approximately 0.76 mg/L at the most.  A blood level of 0.5 to 1.0 mg/L is considered mild exposure. Mild exposure manifests in general weakness, lowered blood pressure, light headedness.  A standard 12 oz pour or bottle would represent a dosage of around 27 mg. 

I could not find a good reference source on the bioavailability of Cyanogenic glycoside nor the rate of degradation to Cyanide in the body.  Nor could I find any reference in a short time to the rate of elimination from the blood stream of Cyanide. 

Not knowing how much you actually added to your batch, it would be impossible to say it is OK or not.  It is certainly a risk that you need to evaluate for yourself.  Honestly if it were me, I would dump the sucker and start over again.  Chalk it up to the cost of learning.

It was a gallon batch, for testing purposes, It was also your standard purple skinned passionfruit and i added 3 whole normal sized passionfruits. I took out the skin part after like 16 hours.

[dtapke]

I'd have to bet that its safe, but I'd definitely toss it. Especially with such a small batch. Alternatively you could likely send it out to a lab for testing (call your local college maybe even?)

my biggest question would be how available the cyanogenic glycosides would be to the wort, and how the fermentation process would reduce the availability of it? Generally to get something in liquid suspension out of a host plant you've got to meet some specific requirements, often changing PH, Temperature, and all sorts of things. This is obvious given our principal interest in beer. If you mash at 20C you're never going to make beer. I imagine extracting Cyanogenic Glycosides have some similar needs to be brought out of their natural, happy home inside the skin and into your wort, but without knowing those requirements its a guessing game, and I'd likely prefer not to bet my life on it.



"Processing operations such as fermentation, boiling/cooking, and drying, applied to process food‐containing cyanogenic glycosides have been reported to reduce cyanide content to acceptably safe levels" (https://www.intechopen.com/books/toxicology-new-aspects-to-this-scientific-conundrum/a-review-of-cyanogenic-glycosides-in-edible-plants)

[Ck27]

I'd have to bet that its safe, but I'd definitely toss it. Especially with such a small batch. Alternatively you could likely send it out to a lab for testing (call your local college maybe even?)

my biggest question would be how available the cyanogenic glycosides would be to the wort, and how the fermentation process would reduce the availability of it? Generally to get something in liquid suspension out of a host plant you've got to meet some specific requirements, often changing PH, Temperature, and all sorts of things. This is obvious given our principal interest in beer. If you mash at 20C you're never going to make beer. I imagine extracting Cyanogenic Glycosides have some similar needs to be brought out of their natural, happy home inside the skin and into your wort, but without knowing those requirements its a guessing game, and I'd likely prefer not to bet my life on it.



"Processing operations such as fermentation, boiling/cooking, and drying, applied to process food‐containing cyanogenic glycosides have been reported to reduce cyanide content to acceptably safe levels" (https://www.intechopen.com/books/toxicology-new-aspects-to-this-scientific-conundrum/a-review-of-cyanogenic-glycosides-in-edible-plants)

I've got just enough time to brew the beer again so I'm going to do it.