A little background - I am cooking for a person who has a specific diet after gallbladder removal. Lots of spices are a no-go, as is onion, any type of hot pepper, tomatoes, etc. Any citrus also causes this person pain.
If I marinate beef in something like an olive oil and lime juice mix, will any of the citrus / acidity remain once the meat has been cooked (assuming it has been marinated for 24 hours)?
As a general rule when cooking for other people, if an ingredient is not allowed, or off the list, it should simply not be used. There should be no consideration given to whether or not the impact of the ingredient remains after preparation. It should just be avoided. Taken to the extreme, the potential is death to the consumer. I emphasize the extreme simply to make the point. There are plenty of ways to overcome the restriction of ingredients. In fact, these restrictions often provide the motivation for new and interesting techniques and flavors. So, skip the citrus, and any other ingredient your guest can't consumer, and find a work-around.
I think for the average person the amount of acidity that remains in a dish like al pastor ,which is marinated in orange juice, would be noticed but not a problem at all. In this case though I would avoid it. I once worked in a nice retirement facility and when it came to dietary needs we took them very serious because people who were recovering from surgery/injuries were prone to complications. Maybe try marinating in soda instead if it meets the requirements.
