I'm writing on behalf Louis Fahrasmane regarding the use of citric versus sulfuric acid for rum production in new American distilleries. The improper selection of acids to acidify a ferment could be the biggest, easiest to resolve quality setback to new rum producers. Fahrasmane is probably the last surviving rum micro biologist to survey and investigate productions at the end of the last golden era. He expressed interest in writing an article on the topic of acid options to help the American industry. I have collected many of his team's papers and have translated quite a few from French on the blog (go to the bibliography at the end):
This is the next great set of rum research that comes after the work of Arroyo. The INRA team even discovered the last great rum yeast that most people are using.
My understanding is that many new American rum producers acidify their ferment primarily with citric acid, but also sometimes malic, tartaric, or even lactic acid. This is done instead of sulfuric acid possibly because of safe handling concerns and the learning curves of new distillers. I think this originates in a few contemporary books aimed at home distillers and not commercial distillers, but it would be great to hear some anecdotes.
A 1985 paper from Fahrasmane (last missing page here), shows how citric acid modifies yeast metabolism and produces an abundance of ordinary congeners that have to be cut away thus shrinking the hearts fraction and forcing distillation at a higher proof. I think Fahrasmane did more earlier work on this and it was part of his PhD thesis.
Fahrasmane would love to know what people are currently practicing and where the ideas came from if they are from specific texts. It would be great to hear production anecdotes of anyone switching from citric to sulfuric acid. I'm hoping to get an informal survey so feel free to start a discussion in thread or reply privately. I'll be translating all the replies to French and sending them to Fahrasmane. If you are currently using sulfuric, but are aware of citric acid anecdotes, feel free to share what you know.
I would love help making this article by Louis Fahrasmane a success and hopefully we can encourage him to keep writing articles for the new rum industry.