Influence of Protein Type on the Antimicrobial Activity of LAE Alone or in Combination with Methylparaben.

Myriam Loeffler,Nino Terjung,Verena Schwab,D Julian Mcclements,Jochen Weiss

doi:10.3390/foods9030270

Myriam Loeffler, Nino Terjung + Show 3 more

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https://doi.org/10.3390/foods9030270

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Abstract

The cationic surfactant Lauric arginate (LAE) has gained approval for utilization in meat products (limit: 200 mg/kg). However, as for other antimicrobials, its activity is reduced when applied to complex food matrices. The current study therefore aims to better understand protein-antimicrobial agent-interactions and their influence on the antimicrobial activity of (i) LAE and (ii) methylparaben against Listeria innocua and Pseudomonas fluorescens in defined model systems (pH 6). Antimicrobials were utilized alone or in combination with nutrient broth containing either no protein or 2% bovine serum albumin, whey protein isolate, or soy protein hydrolysate. LAE was found to form complexes with all proteins due to electrostatic attraction, determined using microelectrophoretic and turbidity measurements. Minimal lethal concentrations of LAE were remarkably increased (4–13 fold) in the presence of proteins, with globular proteins having the strongest impact. Combinations of LAE (0–200 µg/mL) with the less structure-sensitive component methylparaben (approved concentration 0.1%) remarkably decreased the concentrations of LAE needed to strongly inhibit or even kill both, L. innocua and P. fluorescens in the presence of proteins. The study highlights the importance of ingredient interactions impacting microbial activity that are often not taken into account when examining antimicrobial components having different structure sensitivities.

Highlights

Controlling food safety and spoilage has become increasingly difficult
That the antimicrobial efficacy of parabens increases as the chain length of the ester group increases and polarity decreases [16]. This is related to a decrease in water solubility, a key property for antimicrobial efficacy against bacteria that are usually located in the water phase of a food matrix
Our results have shown that the formation of complexes between proteins and ionic Lauric arginate (LAE) is apparently of electrostatic origin and that hydrophobic interactions contribute to the formation

Summary

Introduction

Controlling food safety and spoilage has become increasingly difficult. On the one hand the industry has to cope with consumers’ demand for mildly preserved foods; on the other hand a lot of bacteria associated with spoilage and food poisoning have developed resistance mechanisms against traditional preservatives [1]. Meat and a lot of meat products belong to the group of highly perishable foods. A lot of effort is taken to extend shelf life and to guarantee food safety of these products. Traditional preservatives, such as weak organic acids or essential oils, have already been successfully applied [3,4], the application

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