Cal. Code Regs. tit. 17, § 12405 – Acid Requirements.

(a) All products subject to Section 12400 found to have a pH greater than 4.6 will be restrained.
(b) The pH of low-acid foods may be lowered by the addition of any edible organic food acid such as citric or acetic. Allowance must be made for the fact that certain acids, such as acetic, are quite volatile and rapidly lose their strength when heated in open containers. The Department of Public Health must be consulted to determine the strength and amount of acid to be used for each type of pack and the control measures that are necessary.
Note: For illustration purposes only, the following examples are cited: On the basis of 60 percent solids in a final acidified artichoke pack, the following brines are found to furnish the required pH of less than 4.6:
(1) Unblanched, 0.6 percent citric acid (80 ounces per 100 gallons)
(2) Water blanched, 0.53 percent citric acid (71 ounces per 100 gallons)
(3) Acid blanched in a 1 percent citric acid solution for six minutes, 0.24 percent citric acid (32 ounces per 100 gallons)
(c) Acidified vegetables from a batch previously inspected and released by the Department of Public Health may be repacked in a packing medium of an edible vegetable oil without official reinspection only when adequate records are maintained clearly showing the batch number of the original batch and the date of release thereof and the batch number of the repacked vegetable.