יורה דעה נ״בYoreh De'ah 52

Se’if 1א׳

עוֹף שֶׁנָּפַל לָאוּר וְנֶחְמְרוּ בְּנֵי מֵעָיו וְנִשְׁתַּנּוּ, הַלֵּב וְקֻרְקְבָן וְכָבֵד שֶׁדַּרְכָּם לִהְיוֹת אֲדֻמִּים וְהוֹרִיקוּ כְּכַרְתִּי, אוֹ הַמֵּעַיִם שֶׁדַּרְכָּן לִהְיוֹת יְרֻקִּים הֶאֱדִימוּ, טְרֵפָה אֲפִלּוּ בְּמַשֶּׁהוּ מֵהֶם שֶׁנִּשְׁתַּנּוּ, וַאֲפִלּוּ לֹא הִגִּיעַ לֶחָלָל, כֵּיוָן שֶׁנִּשְׁתַּנּוּ מֵחֲמַת מִכְוַת אֵשׁ סוֹפָן לִנָּקֵב. וְהַכָּבֵד אֵין הַשִּׁנּוּי אוֹסֵר בּוֹ אֶלָּא אִם כֵּן נִשְׁתַּנָּה כְּנֶגֶד הַמֵּעַיִם, דְּהַיְנוּ בָּרֹאשׁ הַדַּק שֶׁלּוֹ וּכְלַפֵּי פְּנִים, אוֹ אִם הוֹרִיק כְּנֶגֶד הַמָּרָה אוֹ כְּנֶגֶד כָּל מְקוֹם חַיּוּתָהּ. אֲבָל הָרֵאָה אֵין חוֹשְׁשִׁין לָהּ, מִפְּנֵי שֶׁצַּלְעוֹתֶיהָ מְגִנּוֹת עָלֶיהָ. הַגָּה: וּטְחוֹל שֶׁהוֹרִיקָה בְּסוֹמְכֵיהּ, אֲפִלּוּ רַק מַשֶּׁהוּ, טְרֵפָה, שֶׁסּוֹפוֹ לִנָּקֵב (בֵּית יוֹסֵף לְדַעַת הָרַשְׁבָּ"א).

A bird that fell into the fire and its entrails were singed and changed - the heart and the gizzard and the liver, whose way it is to be red, and they turned green like a leek; or the intestines, whose way it is to be green, and they turned red - it is a tereifah (an animal with a fatal defect), even in the least amount at all of them that changed, and even if the fire did not reach the cavity; since they changed on account of the burning of the fire, they will in the end be perforated. And as for the liver, the change does not forbid it unless it changed over against the intestines, that is, at its thin end and toward the inside, or if it turned green over against the gall bladder or over against the whole of the place upon which its life depends. But as for the lung, we are not concerned for it, because its ribs shield it. Hagah [Rema]: And a spleen that turned green at its thick end, even in the least amount at all, is a tereifah, for it will in the end be perforated (Beit Yosef, according to the opinion of the Rashba).

Se’if 2ב׳

הָא דְּשִׁנּוּי פּוֹסֵל בְּאֵבָרִים אֵלּוּ, דַּוְקָא כְּשֶׁעָמְדוּ בְּשִׁנּוּיֵיהֶם אַחַר שֶׁשְּׁלָקָן, אֲבָל אִם שְׁלָקָן וְחָזְרוּ לְמַרְאֵיהֶן, כָּשֵׁר.

That a change disqualifies in these organs is specifically where they stood in their changed state after he boiled them; but if he boiled them and they returned to their proper appearance, it is fit.

Se’if 3ג׳

אִם לֹא נִשְׁתַּנּוּ אֵבָרִים אֵלּוּ וְאֵרַע שֶׁשְּׁלָקָן וְנִשְׁתַּנּוּ, טְרֵפָה, כֵּיוָן שֶׁנָּפְלָה לָאוּר.

If these organs did not change, and it happened that he boiled them and they changed, it is a tereifah, since it fell into the fire.