16 hours ago, SweetSymphonybyM said:
I suspect it won't be long, since the water in the purée is not being boiled out like in a jam. The acid might help though. I don't have access to a similar recipe with a known aW value that I could use as a reference either, unfortunately.
I'd suggest contacting your local university/college culinary school and asking if they have an aW meter. If so, make up a batch and let us know the result.
BTW got a link to the full recipe?