How does food composition affect the activity of antimicrobial substances? [06.03.20]
Combinations between the structure-sensitive antimicrobial surfactant LAE and methylparaben were found to have great potential for food applications in general and due to the pH conditions used, especially for applications in meat products. Antimicrobial activity, however, varies depending on the fat content of food. A recent, FEI-funded study by Hohenheim scientists with partners from U Amherst, US underpins the importance of testing antimicrobial agents in complex but defined model systems and yielded first insights on the interactions of antimicrobial agents with ingredients of complex food matrices.
© University of Hohenheim/Astrid Untermann
Myriam Loeffler 1, Verena Schwab 1, Nino Terjung 1, Jochen Weiss 1 and D. Julian McClements 2,*(2020) Influence of Protein Type on the Antimicrobial Activity of LAE Alone or in Combination with Methylparaben. Foods 2020, 9
- Department of Food Physics and Meat Science, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstrasse 21/25, 70599 Stuttgart, Germany
- Department of Food Science, University of Massachusetts, Amherst, MA 01003, USA, *Author to whom correspondence should be addressed.
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.
Keywords: food antimicrobials; structure sensitivity; cationic surfactant; Lauric arginate; protein interaction; methylparaben
