Jerusalem Talmud Pesachim 3:5

משנה: שֵׂיאוּר יִשָּרֵף וְהָאוֹכְלוֹ פָּטוּר. סִידּוּק יִשָּׂרֵף וְהָאוֹכְלוֹ חַייָב כָּרֵת. אֵיזֶהוּ שֵׂיאוּר כְּקַרְנֵי חֲגָבִים. סִידּוּק שֶׁנִּתְעָֽרְבוּ סְדָקָיו זֶה בָזֶה דִּבְרֵי רִבִּי יְהוּדָה. וַחֲכָמִים אוֹמְרִים זֶה וָזֶה הָאוֹכְלוֹ חַייָב כָּרֵת. אֵי זֶהוּ שֵׂיאוּר כָּל־שֶׁהִכְסִיפוּ פָנָיו כְּאָדָם שֶׁעָֽמְדוּ שַׂעֲרוֹתָיו׃ MISHNAH: Sour dough¹⁰⁹Dough in the process of fermentation which is not edible for most people. Extirpation is decreed only for people eating leavened food on Passover. is to be burned but a person who eats it is not liable; cracked dough¹¹⁰Not fully fermented but edible dough. is to be burned and a person who eats it is liable for extirpation. What is sour dough? Like locusts’ antlers¹¹¹The CO₂ created in the fermentation process causes small fissures the size of locusts’ antlers.; cracked if its fissures joined one another, the words of Rebbi Jehudah, but the Sages say, in both cases one who eats it is liable. What is sour dough? Any which is pale like a man whose hair is standing up¹¹². In fear..

הלכה: רַב הוּנָא בְשֵׁם רַב. מוּתָּר לְהַאֲכִילוֹ [לְכַלְבּוֹ.] תַּנֵּי בַּר קַפָּרָא. אֵין לָךְ סֶדֶק מִלְּמַעֲלָן שֶׁאֵין תַּחְתָּיו כַּמָּה סְדָקִין. HALAKHAH: Rav Huna in the name of Rav: One is permitted to feed it [to his dog]¹¹³Since it is inedible, the prohibition of eating cannot imply prohibition of usufruct; cf. Chapter 2, Notes 9,14.. Bar Qappara stated: There is no fissure on top which does not have several fissures below¹¹⁴He gives the reason why the Sages reject the definition of R. Jehudah. Even if only one fissure the size of a locust antler is visible, it is a confluence of a number of interior bubbles. Pesachim.48b">Babli 48b..