berliner weisse - coagulation when I add raspberry syrup?

[canehdianman]

I brewed a berliner weisse in my grainfather about a month ago. Kettle soured with unmilled grain.

Everything seemed to go pretty well. I can post the recipe/process here if necessary, but I don't think it will be... Only important detail I can think of is that I added gelatin to the keg after chilling.

I went to drink some last night. Poured well. had a little haze to it (chill haze I assumed). took a sip, it was nice and tart.

I added a shot of Torani sugar-free raspberry syrup to the pint. Over the next 10-30 seconds, a mass started forming on the top of the beer, in the bubbles. It seemed as though something in the raspberry syrup was coagulating something in the beer? It started off looking like tendrils (which scared me for mold or something), but eventually became a fairly solid lump.

Here is a pic, about half way through its transformation.

https://imgur.com/a/33PUw

It didn't taste bad. I would describe it as somewhat gelatinous (which is why I thought it might have something to do with the gelatin?)

Anyone else encountered this? What is it?

 

[RPh_Guy]

Shot in the dark (no pun intended), but possibly some interaction between xantham gum in the syrup and something in the beer -- maybe gelatin maybe something else.

Seems like a cool trick for parties.