Phosphonate salts are the result of deprotonation of phosphonic acids, which are diprotic acids: Phosphonate esters are the result of condensation of phosphonic acids with alcohols. Several methods exist for the preparation of phosphonic acids and their salts.
1 Stir in the tomato sauce, tomato paste, vinegar, diced tomatoes, and brown sugar. Season with chili powder, Italian seasoning, and salt. Bring to a boil, reduce heat to low, and simmer 1 hour.  Mix the cornstarch and water, and stir into the salsa to thicken. Transfer salsa to sterilized jars, leaving 1/2 inch headroom, and seal. Process jars in a boiling water bath 15 minutes. Store unsealed jars in the refrigerator.
Salsa will begin to look a darker maroon color instead of bright red and will get thicker over time. Eventually, mold will begin to grow at which point you need to toss the entire container of salsa. Generally, if the color, texture, or smell of a food changes from it's original state it's usually been around too long.