A prominent Israeli rabbi recently made headlines for suggesting that artificial meat grown from the stem cells of pigs would be kosher. Gil Student argues that the halakhic consensus is not on the rabbi’s side:
One argument in favor [of permitting the meat] is that the pig stem cells are microscopic. Since the Torah, [according to traditional rabbinic interpretation], does not forbid anything that is invisible to the naked eye, the cell itself is permissible. Therefore, any meat that grows from it must be permissible as well.
Both Rabbi J. David Bleich and Rabbi Ya’akov Ariel point out that in this case we do not discount the microscopic cell because we manipulate it. It comes from a large animal and will grow into a visible item, and, in between, humans interact with it. . . .
[One argument in favor of allowing the meats draws on the halakhic rule that] a prohibited item is permitted when diluted in a mixture in which it is either a simple minority or less than one-sixtieth, depending on the circumstance. When a pig cell is added to a growth medium, the cell is diluted by much more than one-sixtieth. Therefore, it should be permitted. . . .
Ariel, [however, argues] that there is no actual mixture. The pig stem cell is placed in a growth medium and then grows. The result is many more pig cells that grow from the original stem cell. Rather than a mixture, this is just one substance growing substantially. The lab-grown meat consists of the original stem cell multiplied greatly, thus maintaining the forbidden status of the original cell.
Read more on Torah Musings: https://www.torahmusings.com/2018/04/cloned-pigs-arent-kosher/