Citric acid is sold as a white crystalline powder with no aroma. It is a fine grade which makes it easier to work with and makes a much smoother surface bath bomb. Here it is derived from corn (non-GMO) and is COSMOS approved.
It occurs naturally in many fruits and vegetables but is most concentrated in lemons and limes where it can be up to 8% of the fruit content.
Commercially, it is often used as an environmentally benign cleaning agent but in cosmetic production, it is frequently used as an antioxidant.