Description General description cis-4-Heptenal is one of the major carbonyl compounds found in oxidized lipid materials. It occurs in dairy products and seafood. cis-4-Heptenal has also been associated with the off-flavors in fish oil. Biochem/physiol Actions Taste at 20 ppm Other Notes Natural occurrence: Butter, dried bonito, fish, krill, milk, boiled potato, peppermint, Scotch, spearmint, wheat bread. Download our Flavors and Fragrances Catalog to view our entire product line. Subscribe to our Newsletter to keep up to date on our latest Flavors and Fragrances offerings.