A chilling injury...

As I was cleaning out our refrigerator this morning in the Refugio, I came across a long lost banana that I had left in there during the Brazil V. US game. Of course, the banana looked completely nasty, but since I had no other food... I ate it. And you know what? It was good. I mean gooood. So, I decided to look into banana peels and why they turn black and unappealing.

In 2007, there was a study done on how heat treatments effect the browning of banana peels, a.k.a. their chilling injury (or CI). Previous studies had shown that if treated in hot water before cold storage, other tropical fruits showed less ripening and browning, so, why not bananas too? The bananas were gathered at 80% maturity, which is the same maturity that we would buy in a grocery store. They were then placed in water at 42 degrees C for 5, 10, or 15 minutes, then stored at 4 degrees C. At various points during cold storage, samples from the peels were taken to observe any chemical or structural changes.

The results? The main reason for chilling injury is the amount of saturated versus unsaturated fatty acids in the peels. The control bananas (which were not treated with the hot water) showed an increase is saturated FAs and a decrease in unsaturated FAs. The heat treatments prevented the increase in saturated FAs while changing the decrease of unsaturated FAs to an increase in them. Basically, the better the ratio of saturated versus unsaturated fatty acids, the higher the peel's tolerance to cold temperatures. The heat treated bananas began browning four days later than those not treated, and after ten days, the heat treated bananas did not show maximum blackening, while the control bananas looked like the banana I found in our fridge.

So the moral of the story: if you want to store your bananas in the refrigerator without them becoming black and gross, you should try the hot water treatment, and let me know how it goes.


And for your entertainment, here is another experiment done with banana peels brought to you by Mythbusters.... http://www.youtube.com/watch?v=YZRq3XxCZXo


And for further reading on the experiment, here is the paper.
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TBJ-4R5G84B-3&_user=7597297&_rdoc=1&_fmt=&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=947741236&_rerunOrigin=google&_acct=C000036918&_version=1&_urlVersion=0&_userid=7597297&md5=a8368c83c4f5118cb1c9be9b16d375fa