Mulberry pH indicator

I have a multitude of mulberry trees growing on my property - not the tastier Morus rubra but the relatively bland and therefore not very useful (as a food) Morus alba, the white mulberry (or some hybrid that is far closer to the white than the red).

While trying to find some use for them I ran across the following paper describing the use of an extract as a pH indicator for titration: http://sphinxsai.com/CTVOL3/CT=26,%20K%20S%20PATHADE,%20(549-551).pdf
Interesting enough (though hardly a major effort, their work seems like a high school AP Chem project). But lacking in pictures as well as any suggestion as to whether the indicator could be used in small enough amounts to be useful.
Anyway, I decided to reproduce their work. I harvested 110g of ripe mulberries, put them in a 500ml beaker, mashed them crudely, and added 170g of methanol and 3g of 31% HCl. Then I covered the beaker with a watch glass and left the mixture to steep for four days. The mixture was then filtered through a coffee filter.

Adding 200 microliters of the resulting liquid to 50ml of 1% HCl and 50ml of ~10% ammonia gave the results shown in the picture. Much less would probably start to be hard to read as an indicator, though perhaps the solution could be made more concentrated.
The indicator is oxidized to colorlessness by any of H2O2, NaOCl, or longish (1 hour) exposure to air in alkaline solution. In acid solution only NaOCl seems to oxidize it (at least in a small amount of time).

I would note in passing....