Synergistic interactions between natural preservatives maximize functionality

NIZO food research has discovered that synergistic interactions between different natural preservatives can reduce the cost in use, while improving overall functionality.
The natural protein lactoferrin, known to exhibit antimicrobial activity against micro-organisms, combined with an extract of the essential oil thyme oil, almost completely inhibited growth of E. coli because of the synergistic effect of these two natural compounds.

Consumer awareness of additives, and changes in legislation on the usage of antibiotics, are driving the industry to launch natural and/or clean label products and look for alternative antimicrobial agents. Several classes of antimicrobial compounds exist: proteins and peptides, ferments, and natural compounds, such as herb extracts and essential oils. All these ingredients have their own mode of action, with accompanying advantages and disadvantages. Generally speaking the cost in use for natural preservatives is high compared to often highly effective chemical alternatives. NIZO food research has discovered that the effectiveness of different natural preservatives can be improved by exploiting the synergistic interactions between them. As a result cost in use can be reduced.

Clean label antimicrobial proteins such as lactoferrin are known to exhibit antimicrobial activity against different micro-organisms. The action of lactoferrin on micro-organisms is two-fold, due to its iron-sequestering capabilities and the presence of antibacterial peptides comprising the N-terminal part of the protein. Natural ingredients and extracts used for preservation range from ascorbic acid and Maillard reaction products to herbs, spices and essential oils such as cinnamaldehyde, eugenol and thymol. The hydrophobic compounds owe their antimicrobial functionality to the fact that they interact with biological membranes (lipid bilayers).

Synergistic interactions
Recent work at NIZO food research has focused on the synergistic interactions between antimicrobial peptides and natural extracts, as these classes of ingredients display different modes of action. For example both lactoferrin and thymol (the active component in thyme oil) show an antimicrobial activity against E. coli. The combination of both showed an enormous synergistic effect, almost complete inhibition of the growth of this bacterium. Thus the synergistic interaction between different classes of natural antimicrobial compounds increases their efficiency and thereby reduces the cost in use. Dr Tim Lambers, NIZO project leader in charge of this research, sees great opportunities in fresh foods, meat and feed.

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