The Sound of Science - "Fruitcake"

Jan 18, 2019

J: I’m Jeremy Benson from NIU STEM Outreach and I’m in the studio with Kate Powers. This is the Sound of Science on WNIJ.

K: Jeremy, I hear you have a question from Lizzy today. 

J: Yes, Lizzy is concerned that her mom is still eating fruitcake from Christmas. She wants to know if that fruitcake is too old to eat, but I’ve heard stories about really old fruitcakes before. I just figured fruitcakes last a long time because nobody likes them.

NIU STEM Outreach

K: Speak for yourself! I love fruitcake, at least good fruitcake with lots of nuts and dried fruit. But Lizzy is right to be nervous. Normally we would never recommend eating cake that is weeks old. Not only would it taste terrible but it would be dangerous.

J: So fruitcake is not like other cake? I mean I think I already knew that.

K: Well, real fruitcake (in the traditional sense) is made up of a very high ratio of dried fruit and nuts to flour and butter. The high dried fruit and nut content means that there is little water trapped in the cake. In normal cakes the high amount of butter and eggs hold a lot of moisture. Without very much moisture the fruitcake is inhospitable for bacteria.

J: That makes sense; dried fruit and nuts both have a long shelf life. 

K: Yeah, they are low moisture. The fruit is also very high sugar, which creates an acidic environment that retards the growth of bacteria. Just like storing food in salt makes it last longer, so does storing food in sugar.

J: That’s why it used to be popular to candy fruit before refrigeration I suppose. Now, I’ve actually heard that some people think fruitcake gets better as it gets older.

K: That’s true! Up to a point (I have a story about a REALLY old fruitcake for you). Just last year, researchers discovered a century old fruitcake in the Antarctic. The fruitcake was in a tin that was quite a bit worse for wear, but the fruitcake itself was in pretty good shape! The researchers who found it described it as “almost edible”. 

J: I guess in the end days it will just be the cockroaches and fruitcakes left to rule the Earth. The perfect apocalypse food.

K: Something like that Jeremy! So Lizzy, join your mom and tuck into your last pieces of Christmas fruitcake. Keep your questions coming to stemoutreach@niu.edu. This has been the Sound of Science on WNIJ.

J: Where you learn something new every day.