The Immortal Fruitcake: Can We Make Food Last Forever?

Few foods are as closely connected to Christmas as fruitcake, and few foods are as deeply dreaded. To be sure, fruitcake is a strange food. It combines the healthy and nutritious (cherries, mangos, cranberries, etc), with the unhealthy and delicious (sugar, butter, etc.), and coats the whole mess in a tantalizingly glistening layer of alcohol. Put that way, fruitcake shouldn’t have such a bad reputation. Part of the problem with fruitcake, however is that most recipes require you to bake the cake about a month before you plan on eating it. The general rule with preparing one of these masterpieces is “the older the better” as each day you brush on a little more booze to keep the cake moist. An unintended consequence of the liquor, however, is that fruitcake is known to last a really, truly, ridiculously long time.

The Virginia Museum of Science is one of the only sources online that dares to put a figure on the lifespan of fruitcake. They set the expiration date for a properly made cake stored in an airtight container at 25 years. The reason for the inflated lifespan is that fruitcake is by its very nature inhospitable to bacteria, and bacteria are the reason that all foods spoil.

Bacteria cannot survive to breakdown fruitcake because they cannot penetrate the alcohol that encases it. Alcohol kills bacteria by dissolving cell membranes and denaturing the proteins bacteria need to function. Eventually, though, alcohol itself begins to break down and bacteria begin, disappointingly, to penetrate the boozey barrier. Certainly, 25 years is a very long time for a cake to remain edible, but what would you need to do to make one last forever?

Food preservation is something that humans have been working on since we first learned about food poisoning, and we have gotten pretty good at it. Techniques abound but they all work on the same principle: slow down or remove any bacteria or bacterial processes. The most common method is refrigeration which uses cold temperatures to slow down the metabolisms of bacteria and allows food to last much longer. Refrigeration is great for foods that rapidly spoil like milk or meat, lengthening their edibility window from a few hours to a week or more, but it won’t do much to make our fruitcake truly immortal.

Another great option if you want food to last a really long time is canning. Canning involves heating or boiling food at a temperature sufficient to kill bacteria (usually to at least 66°C/150°F). Once the bacteria are dead, you seal the can to prevent any new microbes from staking a claim. All that is left is to put the can away until you’re ready to enjoy its contents. The Food and Drug Administration of the United States has analyzed 100 year old canned fruit from Antarctic expedition and detected no microbial growth, advising that as long as the can itself is not compromised, the food remains edible after a century.  The only drawback to canning is that heating your food can significantly change its taste and texture.

Canning is definitely a great option, but it isn’t the only one that will take a fruitcake to the doorstep of eternity. Dehydrating and Freeze Drying are two more options that work on the principle that bacteria need water to function. Dehydrating is the easier of the two processes. All it requires is that the food be surrounded with sufficiently dry air to draw out all the moisture. The resulting food will last a very long time (ad infinitum if properly stored), but who wants a dry fruitcake? To overcome the obvious shortcomings of moistureless cake, we can freeze dry. To freeze dry our fruitcake, all we need to do it freeze it (which many people will tell you actually improves a fruitcake) and place it in a strong vacuum. The vacuum causes the water in the food to sublimate (turn directly from solid to vapor) and increased its shelf-life indefinitely. To reconstitute our fruitcake all we need to do is add water and microwave. This process is more ideally suited to the fruit portion, rather than the cake.

We now understand a few ways that we can launch a fruitcake into the future, but each has its drawbacks. If we want to eat our fruitcake 10,000 years from now and have it taste pretty much the same as it does today, we have to get nuclear…

Food irradiation can kill bacteria without significantly altering food. All you need to do is seal the food in plastic and zap it with a healthy dose of radioactivity. The result is the most sterile fruitcake possible as long as the seal never breaks. The only reason irradiation is not pursued more actively is that people seem to have a problem putting the words “nuclear radiation” and “food” in the same sentence. But if our goal is to pass a fruitcake on to our great-great-great….great-great-grandchildren, a little radiation seems like it is their problem, not ours. Just include a note that says wasting food puts them on the naughty list.