This is a review paper, not an experimental study, so there are no new test results. It compiled existing research on citric acid production from a fungus called Aspergillus niger—which is commonly used to make citric acid for cosmetics, food, and beverages. The review covers how the ingredient is made industrially and notes that genetic engineering techniques are being used to improve production efficiency.

This wasn't a research experiment. Instead, the author reviewed and summarized all existing published literature on citric acid production methods, fermentation techniques, and genetic modification approaches to create a comprehensive overview of the topic.

Funding not disclosed in abstract