Antimicrobial activity of chitosan, organic acids and nano-sized solubilisates for potential use in smart antimicrobially-active packaging for potential food applications

•The molecular weight (MW) of the chitosan effected antimicrobial activity (AA).•Low & medium MW chitosan had the highest AA against all bacteria tested.•Nano-sized solubilisates of organic acids had higher AA than their non-nano equivalents.

Antimicrobial activity of low- and medium-molecular weight chitosan and organic acids (Benzoic acid and Sorbic acid and commercially-available nano-sized benzoic- and sorbic-acid solubilisate equivalents) was investigated and compared against commercial mixtures of organic acids used as meat coatings (Articoat DLP-02® and Sulac-01®). From the antimicrobials tested, both low molecular weight (LMW) and medium molecular weight (MMW) chitosan exhibited the highest antimicrobial activity against all bacterial cultures tested, with mean MIC values of 0.010 and 0.015% w/v, respectively. The results suggested that the MW of the chitosan used effected antimicrobial activity of the chitosan. Nano-sized solubilisates of benzoic acid and sorbic acid had significantly (P < 0.05) higher antimicrobial properties than their non-nano equivalents. The results found in this study open opportunities for the nano-sized solubilisates, derived from food compatible sources, to be used in smart and active antimicrobial packaging applications, as less of the antimicrobial substances in question is required to deliver the same antimicrobial effect.