What American in the 1920s and '30s could resist the appetizing photographs of gently rippling Jell-O salads in the Ladies Home Journal? The majority of Jews, wanting to embrace everything American, to be part of this new age of science and technology, were open to new products that would shorten their time in the kitchen and these included the new Jell-O desserts.
Quite a stir was made over Jell-O within the Jewish community. "According to our knowledge, Jell-O does not contain any lard or meat shortening," declared a form letter from Jell-O to Jewish homemakers. "The Jewish publications have been carrying the advertising of Jell-O in their columns for the past ten years, and as a result it is used in most Jewish homes, and its popularity among your people has been growing consistently," it continued.
Nevertheless, the Orthodox said that no matter how much of a chemical change the rennet underwent it was still not kosher. Conservatives felt that a chemical change made its original source unimportant. The 1936 Kosher Food Guide included an article entitled "Jell-O -- Is it Kosher or Trefa?" It said that "Jell-O was absolutely trefa as the gelatine contained in this product is derived from trefa bones and parts of skins as for instance the skins of hams, etc. As there is unfortunately no kosher animal gelatine produced, we naturally answered to various inquiries about the permissibility of Jell-O or similar products for consumption by Jews, that these articles are trefa." Until certified pareve kosher synthetic gelatins came on the market, Orthodox Jews would not use any junkets, gelatins, or Jell-Os.