Very cool! From cursory research it seems like many salicylates produce triboluminescence (I don't know why), and some people online with special dietary needs say that bananas are high in salicylates (though it seems controversial). So that would be my hypothesis.

I'm gunnuh try crushing an aspirin (acetylsalicylic acid) and see what happens. (ETA: My headache pills that have aspirin, acetaminophen, and caffeine, along with whatever binders, did not produce any light that my camera detected. That's the only aspirin I have and I'm only willing to sacrifice one of them. Oh well!)

ETA2: Wasn't able to get it to work by peeling a banana, crushing the inside, or crushing the peel, but I don't doubt it happened. Bananas probably vary a great deal. Thanks for the fun diversion, I haven't done an experiment like this in years.

I would think there's some amount you could capture inductively or magnetically, but perhaps it's too small to be useful. Still, feels like fundamental enough science to look into.

Poking at this dissertation (Continuum and Computational Modeling of Flexoelectricity by Sheng Mao):

https://repository.upenn.edu/server/api/core/bitstreams/3bc2...

> Flexoelectricity, ever since its discovery, has been regarded as an alternative of piezoelectricity at small scales. In fact, as early as the 1960s, Koehler et al. (1962), Turch´anyi, G. et al. (1973), Whitworth (1975) found that edge dislocations in centrosymmetric materials, such as sodium chloride, carry charge. Later, Perenko & Whitworth (1983) extended the observation to another kind of centrosymmetric material, ice. Piezoelectricity vanishes in these materials, therefore cannot be the source. Instead, a “pseudo-piezoelectric” effect was postulated by Evtushenko et al. (1987) for an explanation, which was later shown to be a result of flexoelectricity Mao & Purohit (2015).

Emphasis added.

So I think this was known but not fully understood by the time Perenko & Whitworth published Electric currents associated with dislocation motion in ice in 1983?

https://scholar.google.com/scholar?cluster=69134483967663101...

> In this paper we describe [an] experiment in which a small current is observed due to the movement of dislocations during plastic deformation [of ice].

The same authors of the paper TFA discusses published a preprint in 2022, which could also be what you're thinking of: https://arxiv.org/abs/2212.00323