Bring it on home.

From A., 22 November 2010, a question about leftovers.

Q: Restaurant portions are usually too much for me in a single sitting, so I bring home a lot of leftovers. Is there a general good rule of thumb for how long restaurant leftovers are safe to eat, if they’re kept refrigerated? Does it depend on whether they have meat in them? Dairy?

A: Hi, and thanks for your question. I’m just like you – unless I’m ordering small plates at a restaurant, or I’m ordering the tasting menu, I often wind up with leftovers. Obviously, we’re not alone – restaurants all over the United States maintain an array of storage containers, ranging from the archetypical waxed paper Chinese takeout carton to compostable cardboard to reusable, microwaveable plastic trays with lids. In some countries, the expectation of take-home leftovers is so great that meals may be structured in anticipation of leftovers. I once attended a wedding in Taiwan where, at the end of the wedding banquet, each guest received a plastic bag full of packed boxes containing each course. In other countries, though, etiquette forbids taking home leftovers. Good luck taking home the rest of your onglet aux pommes frites in Lyon.

I try to eat restaurant leftovers within a couple of days – usually, they last only that long anyway before becoming lunch. The Department of Agriculture recommends consuming leftovers within four days, if your refrigerator is at a proper temperature (below the danger zone, under 40F/4C). Before eating leftovers, reheat thoroughly by bringing to 165F/75C. Of course, if you’re talking about medium-rare beef or something, you will sacrifice quality by following this reheating rule, so I don’t, but I also don’t kid myself that the inherent risk is somewhat higher. Because leftover food meant to be eaten cold (or not reheated to 165F, anyway) needs to be kept safer, don’t wait hours to refrigerate it. Try to refrigerate it immediately, or within an hour or so of dining.

By the way, since today is Thanksgiving, this is an excellent time to review the rules for handling leftovers before they go into the refrigerator. The danger zone for pathogenic growth is 40F/4C to 140F/60C. Below this range, bacteria propagate far more slowly, and above it, most cannot survive. Above 90F/32C the rate of pathogenic growth increases dramatically. Don’t leave food out longer than two hours at ordinary room temperature before packing it up and putting it in the refrigerator. If it’s really hot (over 90F), which is really more of a concern in summer and not at Thanksgiving, but still, don’t leave food out for more than an hour before refrigerating. Even if you are able to destroy pathogens in food through proper reheating, some bacteria produce toxins that cannot be destroyed with heat.

So, to recap:

* Don’t let your cooked food sit out for more than a couple of hours before you pack it up and put it away.
* If it’s super warm in the room (over 90F), don’t let it sit out for more than one hour before putting it away.
* Food meant to be eaten cold should be held on ice, or leftovers should be refrigerated immediately.
* If you can’t refrigerate immediately, you can reheat appropriately (to over 140F/60C for holding, or 165F/75C if not holding, but then refrigerate within the safe period)
* Don’t prepare food, or handle it for others, if you have a gastrointestinal illness.
* Eat your leftovers within four days, or freeze them.