By Rabbi David I. Sheinkopf

Gelatin produced from cattle bones or hides of even non-ritually slaughtered animals is kosher in full accordance with orthodox Jewish dietary laws. The reason is that only the edible parts of non-kosher animals are forbidden. Bones and hides, however, which are inedible, are excluded by the Talmud and Jewish Law Codes from any category of foodstuffs. Therefore, after undergoing chemical pretreatments which render them absolutely free of any forbidden extraneous materials, bones and hides in themselves are permissible.

Soaked in hydrochloric acid and/or lime for extended periods of time, the raw material is reduced to pure collagen with no traces of adhering flesh, marrow, or grease whatsoever. (Those who contend otherwise are simply unfamiliar with the manufacturing process.) Hence, the gelatin extracted from the collagenous residue of bones and hides is kosher. This is true regardless of whether gelatin is considered a new substance (davar hadash). Also, because it originates from a non-edible substance, gelatin is pareve (neither meat nor dairy.)

On the other hand, pigskin, which Jewish Law equates with flesh itself, is rejected by nearly all rabbinic authorities as a source of kosher gelatin. It is true that pigskin becomes unfit for consumption in the extraction tanks where it is treated to acid and dissolved into protein solution. At a later stage, however, as the acid is removed, the solution becomes edible and is then subject to the rule of hozer venei'or, by which the prohibition of the original material reverts. Neither can pigskin gelatin be considered kosher as a new substance because that too must originate directly from an inedible substance. By contrast, the removal of the acid from bones and hides during the manufacturing process does not affect the kashrut of gelatin derived from these raw materials because bones and hides, unlike pigskin, were never considered edible in the first place. The upshot of all this is that gelatin made from bones or hides is kosher. Pigskin gelatin is not. The kosher consumer should note the difference.

Among the chief rabbinic decisors for the approval of bone gelatin as kosher are: R. Hayyim Ozer Grodzienski, (Ahiezer, vol. 3); R. Yosef Konvitz (Divrei Yosef, vol. 1); R. Ezekiel Abramsky (Tzitz Eliezer, IV); R. Yehudah Leib Seltzer (Vetzot Lihudah); R. Yosef Henkin (Edut LeYisrael); R. Simcha Elberg (HaPardes, Tammuz 1952). Bone gelatin has also been approved by other noted authorities in the State of Israel, including but not limited to, R. Tzvi Pesach Frank (Chief Rabbi, Jerusalem); R.Yizhak Halevi (Chief Rabbinate, Israel); Rabbi Shlomo Schreiber (Agudat Yisrael, Jerusalem); and Rabbi Michael Ehrlich (Chief Rabbinate, Tel Aviv). This same gelatin is approved today by Israel's Chief Rabbinate with the stipulation, "for those who allow gelatin". See also comprehensive responsum by Rabbi Ovadia Yosef, former Sephardic Chief Rabbi of Israel (Torah Sheb'al Peh, ed. Y. Rafael).

Rabbi David I. Sheinkopf was ordained at Mesivta Rabbi Chaim Berlin and earned a doctoral degree in Judaic Studies from Yeshiva University. He is the author of Gelatin in Jewish Law (Bloch, 1982) and Issues in Jewish Dietary Laws, (Ktav 1988), and Expositions in Jewish Dietary Laws (Ktav 2010). Each of these studies devotes a full chapter to the annulment of Jewish dietetic prohibitions in substances rendered unfit for animal consumption.