I am using citric acid as a preservative for peanut sauce. The 1tsp per quart is not strong enough. Is it safe to use a higher concentration? My peanut sauce is currently at a pH of 4.5, I need <4.3. I don't want to water down the sauce any more than it already is. I will be hot pack bottling, maybe.
According to (US) Code of Federal Regulations on Citric acid:
(c) In accordance with § 184.1(b)(1), the ingredient is used in food with no limitations other than current good manufacturing practice. (d) Prior sanctions for this ingredient different from the uses established in this section do not exist or have been waived.
Basically, you can eat the stuff by the spoon-full if you can stand the sour. If you're adding a lot compared to how much you think you should have to add, you might consider Phosphoric acid instead. You get a little more bang per mole pH-wise with that, and it too, within limits, is generally regarded as safe (GRAS).