r/Judaism 1d ago

Halacha Siur, sidduk and chametz

In the Talmud there’s a description of the stages of dough turning into chametz, namely siur and sidduk.

There is some disagreement on exactly what is what at each stage, but overall the process is described as

  • Dough turning pale (like the color of someone’s face when their hair stands on its end due to fear. This may be the criterion for siur

  • When cracks form that look like locust antenna. This may be the criterion for siur

  • When the cracks intermingle…this is sidduk.

So when cracks intermingle, that is sidduk and thus full chametz. Does anyone have photos of doughs that exhibit this behavior, so we can see each stage?

How long approximately in standard room temperature does it take to reach each stage for an unyeasted dough without a sourdough starter like se’or?

Thanks!

2 Upvotes

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u/IbnEzra613 שומר תורה ומצוות 1d ago

I've always wanted to test this out. In the Yerushalmi, it says the time to walk from two particular cities which are 4 mil apart (thus some have proposed that the 1 mil in the Bavli is an error due to being unfamiliar with the geography of Eretz Yisrael). The mil is the Roman mile which is about 0.92 US miles. According to Google, an average walking speed is anywhere between 2.5 to 4 miles per hour. The means the time it takes to walk one Roman mile is anywhere between ~14-22 minutes, thus 4 Roman miles would be ~56-88 minutes. But it would be interesting to actually knead some dough and leave it and see how long it takes.

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u/Complete-Proposal729 23h ago

Yes thank you for recognizing that the original Halacha is probably 4 mil and not one as a simple google maps search will tell you

https://maps.app.goo.gl/g6fzSF9UU3EkP4p89?g_st=ic

But yeah it seems like this should be an easy experiment to do

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u/Thebananabender Secular Mizrahi Jew 1d ago

Generally, the time the dough is still not hametz is 18 minutes (or mil= the time it takes to walk a mil which is roughly a kilometer)

So 15 mins or so is just fine.

Fur the accurate stages, some say that the second stage happens some time later after 18 min…

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u/Complete-Proposal729 23h ago

The 18 min thing (or time to walk a Roman mile) is technically for a deaf dough. That is one that does not show signs of fermentation and one for which another dough that does was not made at the same time. Nowadays we treat all doughs as deaf, and we even take another stringency. According to Jewish law the 18 min is resting time after kneading, not time after flour meets water.

But that doesn’t mean that that tells us how to identify the signs for a dough that does show these signs.

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u/IbnEzra613 שומר תורה ומצוות 23h ago

That's an Ashkenazi stringency for the most part. Some Ashkenazi acharonim have said that if you knead a dough and then stop, the heat from the kneading might cause the dough to ferment instantaneously (I guess with the help of SuperYeast, pictured below).

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u/Complete-Proposal729 12h ago

Yes.

It bothers me that the 18 min thing is so widely known because most people misunderstand the actual rules.