If you discover that your freezer has been open for 10 long, warm, tragic hours, how do you decide what’s still safe to eat and what definitely needs to be tossed?
It’s not easy! And it’s heartbreaking. I learned all this firsthand when it happened to me, and recently wrote up the experience for The Washington Post.
The article covers my sad story, as well as broad food safety considerations, including that heating food that’s been left out too long won’t necessarily eliminate risk, and that foods with water that’s tightly bound up (like cakes and jams) are less susceptible to problematic bacteria growth.
But for anyone craving more details, or currently squinting at some questionable victims of a vicious defrost, here’s an item-by-item analysis of some of the items in my freezer.
Tomato salsa. This was totally defrosted; it sloshed around when I picked it up. Initially I hoped that the tomatoes might be acidic enough to combat bacterial growth, but alas, while tomatoes are acidic, they are not necessarily acidic enough to keep dangerous pathogens at bay. On top of that, I had rescued this salsa from a party so it had already spent a fair amount of time outside of refrigeration (freezer and fridge temperatures don’t kill bacteria, they just slow or pause their growth).
Naan, wrapped in a plastic bag. This defrosted, but as a bread, it wouldn’t be a friendly host for bacteria. The naan would more likely to succumb to mold, which would be visible and probably need more time than the 10 hours my freezer was open.
Frozen tater tots. The packaged tater tots looked fine, but, as we know, human pathogens are invisible to the human eye. While presumably the tots would have been safe to cook from frozen, Rutgers University food microbiologist Don Schaffner pointed out that since potatoes grow underground, the tots were more likely to have low levels of certain soil-dwelling spores on them. Like bacillus cereus, for example. With safe handling, such spores would have been harmless, but with enough time at a warm enough temperature the spores could have “woken up,” turned into cells, and then proliferated enough to leave behind a literally gut-wrenching toxin.
Sauteed vegetables, including spinach, red pepper and tomatoes. I had cooked down the remains of a salad and some vegetables I didn’t think we'd get to in time. I put them in a jar, stashed them in the freezer and looked forward to later heating them up and tossing them with some pasta. Since they were exposed to bacteria-killing heat shortly before I froze them, it’s unlikely they had anything unpleasant remaining on them. On the other hand, it’s still possible they carried some spores (like the tater tots), and even with the most thorough heating, it’s possible I could have contaminated them in the process of putting them in the jar. Here’s the thing: one common cause of food poisoning is a bacterium called staphylococcus aureus. It tends to live on the surface of our bodies, typically kept from proliferating by our immune systems. But when it’s hanging out on food that’s warmer than standard refrigeration temperatures, the bacteria can reproduce, eventually generating enough toxins to make us sick. Heat will kill the bacteria, but the toxins will remain.
Frozen wine. Schaffner declared this to be one of the items he would most comfortably consume from my open freezer, at least in terms of safety. The alcohol and acidic conditions made it hard for anything problematic to grow. I kept it, but the wine, which probably logged at least six months in the freezer, no longer tasted good. As long as it's kept frozen, food and drink won't become unsafe, but its quality can decline over time.
Verdict: SAMPLE, then TOSS.
Don Schaffner. Microbiologist. Extension Specialist in Food Science and Distinguished Professor at Rutgers University.
pH Values of Common Foods and Ingredients. Retrieved from Clemson University website.
Burning Issue: Acidifying Tomatoes When Canning. Why do I have to add acid when canning tomatoes in the pressure canner?? National Center for Home Food Preservation. University of Georgia.
Food Microbiology: An Introduction. Karl R. Matthews, Kalmia E. Kniel, Thomas J. Montville. Fourth Edition. ASM Press. 2017.
Bacteriological Analytical Manual. Chapter 14. Bacillus cereus. Sandra M. Tallent, Ann Knolhoff, E. Jeffery Rhodehamel (ret.), Stanley M. Harmon (ret.), and Reginald W. Bennett (ret.)