Why do Lifesavers no longer produce a blue flash, but Altoids still do?

[Ivan Seeking]

Most nerds know that if you crunch a wintergreen lifesaver in your mouth or with a pair of pliers, it flashes blue light due to triboluminescence, . Breaking the bonds in the sugar molecules releases UV, which is then re-emitted as blue light by the wintogreen flavoring [ Methyl salicylate ] due to fluorescence. It has long been a fun, favorite science demo for kids.

Recently I mentioned this to a young engineer at work who immediately had to try it. But she said it didn't work! WHAT? So I picked up an identical product which also did not produce a flash. But Wintergreen Altoids do flash.

I am wondering if the use of corn syrup as a sweetener could be the problem. I haven't dug into the chemistry but it struck me as a suspect when I read the ingredients label. Also, the Altoids, which do still flash, list natural and artificial flavoring. The Lifesavers only list artificial flavoring. So I wonder if they stopped using natural wintergreen oil. in any event, I thought it would be fun to figure out what has changed. l

It is too bad that this fun demo seems to be going away.

 

[jedishrfu]

@Borek may have an answer. Calling @Borek you’re wanted in the candy aisle.

 

[Borek]

Nah, we don't have these here so I am clueless.

 

[Tom.G]

Can we send you some for evaluation?

 

[BillTre]

Here is a nice video of the flash, with explanation.

Here is one with more general explanation, not as good pix.

It seems it goes:
break crystal --> separate charges --> get spark --> UV photon --> make fluorescence with neighboring molecules

Added chemicals can interfere with the fluorescent step (can be a problem with fluorescent microscopy).
I don't know about the other steps.

 

[jedishrfu]

I found this article too that gets into the history of the phenomena:

http://www.todayifoundout.com/index...avers-spark-when-chewed-not-just-wintergreen/

 

[Ivan Seeking]

Here is one with more general explanation, not as good pix.

OMG I am all excited now. Triboluminescence has sparked my imagination! :D As the man says, this might be used as an engineering tool for the detection of friction, stress/strain, and fracturing, in a wide range of materials. I can easily imagine using this knowledge for what I do.

 

[Ivan Seeking]

PS, if anyone has a UV camera, maybe you could try this with lifesavers and see if you get a UV flash when you crush one. Have we lost the UV flash completely or just the fluorescence in the visible range?

 

[hutchphd]

Perhaps it would be easier to see if they fluoresce under UV

I have amazed and bemused countless folks of all ages with the Wint-o-green blue flash. I would be more upset by the change but at my age any attempts to produce the flash could well invite dental repair. So it goes. Very interesting though.