GG, wow, ph of 3 is quite low. Tomatoes are safe in the PH of 4 range.
I have litmus paper, it is not expensive but it doesn't last for years either. I wouldn't get hung up on getting a ph meter but your final product should be acidic and it should taste acidic (which orange juice does).
If you are only using a 1 inch knob of ginger, and 2 cloves of garlic, that is not a majority of the recipe. It would be like adding garlic to dill pickles so it will be okay to water bath can it.
National Center for Home Food Preservation | How Do I? Jam and Jelly
Here is a peach-orange marmalade.
- 5 cups finely chopped or ground peaches (about 4 pounds peaches)
- 1 cup finely chopped or ground oranges(about 2 medium-size oranges)
- Peel of 1 orange, shredded very fine
- 2 tablespoons lemon juice
- 6 cups sugar
Here is marinated peppers with optional horseradish and garlic:
National Center for Home Food Preservation | How Do I? Pickle
- 4 lbs firm peppers*
- 1 cup bottled lemon juice
- 2 cups white vinegar (5 percent)
- 1 tbsp oregano leaves
- 1 cup olive or salad oil
- 1/2 cup chopped onions
- 2 cloves garlic, quartered (optional)
- 2 tbsp prepared horseradish (optional)
I would consider the garlic and ginger you are using, similar to the optional ingredients in the marinated peppers recipe.
This is a syrup recipe (no acid except the fruit juice itself):
National Center for Home Food Preservation | How Do I? Can Fruits
- 1¼ cups juice (see Making Mayhaw Juice below)
- 1½ cups sugar
- ¼ cup white corn syrup* (or ¼ more sugar)
*Using Part corn syrup adds thickness without extra sweetness.
The corn syrup is optional, use sugar instead. (unless the thickness is wanted) The proportions of juice to sugar here is 1 and 1/4 cup syrup to 1 and 3/4 cup sugar. (5 to 7)
So if I was making it for my family, I'd use a recipe most similar to the ingredients and the amounts of ingredients I wanted in my recipe. I wouldn't worry much about the thickness or viscosity of the end product, since it could be thinned out when heating it to serve.
All the recipes are for water bath canning but pressure canning is preferred, you say, so pressure can it, it can't hurt it. (with those ingredients) I wouldn't say pressure can sauerkraut or pickles because that will make your product mushy.
Does this help or make it more difficult to decide?