Hello and welcome to MedHelp's forums. Thanks for your question. Do you, in general, suffer heartburn or acid reflux/gerd? Typically, when acid backs up the esophagus and gets into our mouth, it has a rather distinctive taste. I don't think you really need to test the ph of it to tell. Especially if you have gerd and it is coming up to your throat say after a burp. Here is a symptom tracker that you can use to also help. https://symptomchecker.webmd.com/single-symptom?symptom=taste-of-acid-in-mouth&symid=191
Best to see your doctor for evaluation. Gerd is very treatable. Let us know how you are doing.