Preservation attributes of the organic acids

chemicalmattchemicalmatt Member, Professional Chemist
Without spending lots of time on the phone discussing the matter with manufacturers or searching online, I thought I'd pitch to the forum here. Of the several preservatives that are only effective (pH < 6) as dissociated organic acids, e.g. benzoate, sorbate, dehydroacetate, why would you use more then just one? Isn't there a hierarchy of efficacy known? And if there is, say its benzoate ion, why use any other. I've noticed some manufacturers using two or more in their blends. Solubility is the only factor I can identify. Discuss. 


  • PerryPerry Administrator, Professional Chemist
    I would think that the different acids have a different level of activity against various organisms.  Maybe there is some bacteria that can tolerate sorbic acid but gets wiped out by benzoic acid.  Just my guess.
  • MarkBroussardMarkBroussard Member, Professional Chemist
    I suspect the same ... the different acids may have different modes of action and one alone is insufficient to stop microbial growth ... and/or one acid might function as a baceriocide and the other as a fungicide.
    Chemist/Microbiologist formulating in the Organic & Naturals arena under ECOCert/Natural Products Assn/Whole Foods/National Organic Program guidelines focused skincare & haircare products. 

    See website for details
  • DASDAS Member
    Synergy could be another reason.
  • ozgirlozgirl Member, PCF student
    It could also be due to keeping them below regulatory limits. If you use two actives both at or below regulatory limits you might get greater effectiveness.

    Using two actives at low levels might also reduce the likelihood of adverse reactions to the consumer compared to a single active at a higher level. 
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