The antimicrobial effect of organic acids lies in the reduction of
pH, as well as the undissociated form of the molecules. It has been
proposed that the low external pH causes acidification of the cell
cytoplasm, while the undissociated acid, being lipophilic, can diffuse
passively across the membrane. The undissociated acid acts by
collapsing the electrochemical proton gradient, or by altering the
cell membrane permeability which results in disruption of substrate
transport systems