Dunn did say you can combine a chelator with an antioxidant to effectively reduce the chance of rancidity (DOS), but you do not HAVE to.
He recommended a combination of (BHT + citrate) as being the most effective of all the combinations he tried. Other effective treatments were EDTA alone or (EDTA + rosemary oleoresin) or (EDTA + citrate). What did not work for Dunn in his experiments was the combination of (BHT + citrate) or using citrate alone.
That appears to remove the use of citrate alone as an effective prevention against rancidity, but keep in mind that Dunn was doing a limited set of experiments under controlled conditions. Since his report about this work, people are adapting that information to suit their needs. That gives us a broader field of information to look at, so we should not only look at Dunn's experimental findings, but we also need to look at whether real world soapers are getting similar results in their real-world soap.
What people are seeing in real life generally support his findings, except it looks like citrate alone may be more effective in preventing rancidity than Dunn predicted. Soapers are using citrate in higher dosages than he did in his experiments, however, and that might be the key reason for the difference.
So don't eliminate the option to use citrate alone -- it may work better than you think. In addition, citrate is an inexpensive chemical that can be made from citric acid and a bit of lye or other alkali. Of all the chemicals that can be used to control rancidity, citrate is an easily available and inexpensive treatment available to soapers worldwide. For example, I can go to my small rural grocery store and buy enough citric acid to treat many batches of soap. I cannot buy BHT, EDTA, ROE, etc. in my local area.
