- 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.).
- pH ≤ 4.2 requires a thermal process of approximately 180°F for 1 minute
- 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)
- 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
- pH ≤ 3.3 may be cold filled provided its held at room temperature for 7 days before sale
- other scientific references may exist; e.g. mustards and mayonnaise-based foods.
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).
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: 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.