From Reactions.

While it looks easy on paper to make citric acid at home, Chem Thug runs into some pitfalls trying to extract it from some citrus fruit and mold broth. Even though we discovered getting it out of lemons more than 200 years ago, it’s still tricky chemistry to pull off. Watch him struggle with a fermentation broth and battle with citrus fruit, will he be able to extract any citric acid?

Producers:
Andrew Sobey
Elaine Seward
Darren Weaver

Assistant Editor:
Stephanie Castillo, PhD

Writers:
Chem Thug, PhD

Hosts:
Chem Thug, PhD
Alex Danis, PhD

Executive Producer:
Matthew Radcliff

Scientific Consultants
Brianne Raccor, PhD
Michelle Boucher, PhD

Executive in Charge for PBS: Maribel Lopez
Director of Programming for PBS: Gabrielle Ewing
Assistant Director of Programming for PBS: John Campbell

Reactions is a production of the American Chemical Society.
© 2025 American Chemical Society. All rights reserved.

Sources:

Citric Acid: Properties, Microbial Production, and Applications in Industries | MDPI
https://pmc.ncbi.nlm.nih.gov/articles/PMC10779990/
Citric acid bioproduction and downstream processing: Status, opportunities, and challenges| Bioresource Technology https://www.sciencedirect.com/science/article/pii/S0960852420317004
Recovery of Citric Acid – a Review | Bioprocess and Biosystems Engineering https://www.sciencedirect.com/science/article/pii/S0960852420317004
Overview of citric acid production from Aspergillus niger | Frontiers in Life Science https://www.tandfonline.com/doi/full/10.1080/21553769.2015.1033653

Oxalic acid production by citric acid-producing Aspergillus niger overexpressing the oxaloacetate hydrolase gene oahA | Journal of industrial Microbiology and Biotechnology https://pubmed.ncbi.nlm.nih.gov/24615146/