Bromelain
Bromelain was a plant enzyme that appeared in several types of fruit and foliage, including – but not limited to – pineapple. 

Lieutenant Malcolm Reed was allergic to this compound, but was able to consume it as a result of targeted treatments including regular injections, administered by Doctor Phlox. In 2151, Hoshi Sato used this information, given to her by Pholox, to determine what Reed's favorite food might be. He cautioned her that this fact did not necessarily mean pineapple was the food in question, but a frustrated Sato figured it was "close enough". ()

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 Biochemical compounds