GELATIN

Chester Leach Maddox gave us the gift of gelatin as a binder for the silver halides in a photographic (and later holographic) emulsions, and this food substance is still used, and also used to record holograms when sensitized with dichromate..

Here is what the Photo-Lab Index from Morgan & Morgan has to say about it:

PLI Gelatin

To show the importance of gelatin, legend has it that the Eastman Kodak Company had their own herd of cows, specially fed so that their gelatin supply was as consistent as they could get.