SAFE ACID LEVELS !!

GUIDANCE: The most important factor is that the pH of your product absolutely MUST be pH ≤ 4.6  AND most published scientific data on thermal processing essentially require one of the the following:

  1. pH 4.2 to 4.5 require a thermal process approximately 200°F for 30 minutes (typically these foods are cooked in batch for this time and then bottled as in item number 2.).
  2. pH ≤ 4.2 requires a thermal process of approximately 180°F for 1 minute
  3. pH ≤ 3.8 with 0-20% mustard flour and ≥1.0% acetic acid may be cold filled provided its held at room temperature for 7 days before sale (mustard only)
  4. pH ≤ 3.8 with 1.5% acetic acid AND 0.1% sodium benzoate may be cold filled provided its held at room temperature for 7 days before sale
  5. pH ≤ 3.3 may be cold filled provided its held at room temperature for 7 days before sale (most references are based on acetic acid)
  6. Other scientific references may exist; e.g. mustards and mayonnaise-based foods.
LIMITATIONS
Note a few limitations on the scientific references mentioned above:

  • You cannot cold fill anything pH > 3.8 regardless of the formulation.
  • Expect a higher and longer thermal process for foods between pH 4.2 and 4.5.
  • There are currently no scientific studies permitting canning foods pH > 4.5 without using a pressure or low acid thermal process (temperatures approx 230-240°F).
  • When cold filling you MUST address spoilage.  You should either prove via lab studies ($$) spoilage doesn’t occur or use preservatives (e.g. sodium benzoate and/or potassium sorbate).
FAQ
Q: What about sugar syrups with a pH > 4.5?
A: Sugar syrups can be thermally processed without the need for a pressure process only if the water activity (Aw) is ≤ 0.85.  Water activity is measured using a water activity meter that typically costs $1500 to $4000.  A testing lab can provide this information for a fee.  Never reduce or remove the sugar in these types of products or the safety factor inhibiting botulism will also be removed.
Q: What about coffee or tea beverages?
A: A: Both coffee and teas have a pH ≥ 4.6.  Therefore, they are low-acid foods.  You must add an acidifier to them such as lemon juice before they can be thermally processed below 200oF.
Q: What if I have a totally novel product?
A: A: Acid or acidified foods that lack scientific references for thermal processing may need a microbial challenge study ($$$$$).