ISHS Acta Horticulturae 709: I International Symposium on Natural Preservatives in Food Systems
NISIN SYNERGY WITH NATURAL ANTIOXIDANT EXTRACTS OF THE HERB ROSEMARY |
| Authors: | L.V. Thomas, T. Isak |
| Keywords: | nisin, rosemary, natural food preservative, natural antoxidants, carnosol, carnosic acid |
| Abstract:
The bacteriocin nisin is active against both food spoilage and foodborne pathogenic Gram-positive bacteria. Previous studies have demonstrated that nisin activity can be enhanced in combination with chelating agents, certain emulsifiers and essential oils of herbs. Such combined food protection solutions offer the benefits of a multiple hurdle system, which gives better prevention of the emergence of less sensitive organisms and which may also reduce the required dosage of a single preservative. The present investigation examined the combination of nisin with natural extracts of the herb rosemary (Rosmarinus officinalis) containing high levels of antioxidant phenolic diterpenes and low levels of flavour compounds such as essential oils. In vitro testing demonstrated such a combination to be synergistic. The rosemary extracts enhanced both the cidal and static antibacterial activities of nisin against Gram-positive bacteria. Comparative testing with differently processed extracts identified the phenolic diterpenes carnosol and carnosic acid as the primary synergists. The synergism was demonstrated against Listeria monocytogenes and Bacillus cereus in vitro and in chilled, pasteurised food models (chicken soup, meat and cheese pasta sauces). The effect was increased by low temperature and acid conditions. | |
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