Impact of lauric arginate application form on its antimicrobial activity on the surface of a model meat product

Abstract

This study evaluated the antimicrobial effect of N(α)-Lauroyl-L-arginine ethyl estermonohydrochloride (lauric arginate), sodium lactate, and sodium diacetate at various concentrations against Listeria innocua, Escherichia coli C600, and Lactobacillus curvatus (10(2) CFU/g) on "Lyoner style" sausage slices as a function of application form. We want to investigate if the results of a surface application of lauric arginate in various applications forms may differ from that of an in-matrix application since different physicochemical processes occur at surfaces than in matrices. Lauric arginate was applied on the surface of meat emulsions as aqueous solution, as oil-in-water emulsion, and as solid lipid particles. The sausages slices were stored at 6 °C for 24 d and bacterial growth was assessed every 3rd day. The growth of L. curvatus was not impacted by lactate and diacetate at any tested concentration. In contrast, L. innocua and E. coli were inhibited over 24 d in the presence of ≥3.0 × 10(3) μg/g diacetate. Aqueous lauric arginate solutions of 2.0 and 2.5 × 10(3) μg/g were required for total inhibition of L. curvatus and L. innocua, respectively. The growth of E. coli was not affected by application of lauric arginate. The use of lauric arginate in an oil-in-water emulsion or solid lipid particles reduced antimicrobial effectiveness on the surface of Lyoner slices, which is in stark contrast to a previously conducted in-matrix application of the same systems. Results were attributed to molecular interactions and mass transport processes that rendered lauric arginate less active when applied as emulsions or solid lipid particles. Results highlight the importance of understanding physicochemical properties when using interfacially active antimicrobials.

Practical application: This study demonstrates that the antimicrobial efficacy of preservatives in a product depends on the type of preservative and the time of addition at which the preservative is introduced into the production process. Furthermore, application systems for preservatives can indeed prevent unwanted interaction with product ingredients and therefore a loss of antimicrobial activity but also in this case the time of addition is critical because the preservative must have the possibility to separate from the carrier system.

Keywords: Escherichia coli; Lactobacillus curvatus; Listeria innocua; application form; lauric arginate; meat product.