We've got a home canning work party to put up tomatoes scheduled for friday. But the participants are having a raging debate about whether we need to add citric acid complying with USDA recommendations or go with the classic Italian methods of just tomatoes and salt. We're using San Marzano variety, which potentially fall into the danger zone of lower acid.
I was hoping to get my hands on an inexpensive and accurate for our range (ph of 4.6 +/- 0.5) that would allow us to test each batch and decide whether an acid addition was needed or not. Potentially those would be the lots that we decide to freeze instead of can. Since the event is this week, I need something readily available and wondered if there might be some kind of medical home testing, swimming pool supplies, etc. that would be suitable. Ideas?