Dear Fellow Bread Bakers,
At long last, I have an answer to the posting (bread-bakers.v104.n005.9)
concerning poisoning about my recipe for waffle batter
(bread-bakers.v104.n004.1). For those who do not recall, a poster was
concerned that the batter for my recipe for yeasted waffles would become
poisonous as it fermented overnight at room temperature. I wrote to Prof.
Hammes, a microbiologist at the University of Hohenheim in Germany who
specializes in studying fermented foods, asking him if leaving a milk based
batter to ferment overnight was dangerous. A colleague of his, Michael
Seitter, replied.
Here is his response:
>I do not think that you can poison people with this recipe. You make a
>sourdough with instant yeast. Instant yeast contains commonly also >10000
>lactic acid bacteria (LAB) per gram as contaminants. Over the fermentation
>time of 12 hours at room temperature the LAB produce lactic acid, which
>causes a pH decrease to about 4 to 5. If you do add yogurt, which is also
>a safe lactic fermented food the batter becomes safe against spoilage by
>other microorganisms at once, because the yogurt already has a low pH of
>about 4 to 4.5.
>
>The only point of slight risk in the recipe is that if you don´t work
>asseptically in making your mixture therefore Staphylococci may grow and,
>before the pH drops to the safe range, may cause food poisoning by Toxin
>which is heat stable.
>
>I suggest you that you take pasteurized or UHT-milk for the dough and not
>raw milk.
>
>If you want to play safe you can additionally hold your batter in the
>refrigerator, here the yeast can ferment the batter and no other
>pathogenic microorganism can grow up during the time of fermentation.
>Additionally can you increase the yeast, 1 kg of instant yeast replaces 3
>to 4 kg of compressed yeast. You should have about 1% of compressed yeast
>in the batter.
The conversion to 1% compressed yeast is 0.25% instant yeast, which in this
case is 0.4 teaspoons yeast (based on about 450 g flour, and about 3 g
instant yeast per teaspoon). The original recipe calls for 1/4 teaspoon
yeast, so I would just round it up to 1/2 teaspoon if you are concerned.
Better yet, work clean and wash your hands well!
I hope this clears up the issue.
All the best,
Maggie Glezer