Orange essential oils show promise as natural antimicrobials

 organic essential oils As part of a general shift towards natural and organic foods,consumers increasing prefer foods that do not contain syntheticpreservatives or antimicrobial agents. At the same time, however, salmonella is a major concern for food safety. In 2006 in the US, theinfection rate was 14.8 cases per 100,000 persons. The HealthyPeople 2010 Initiative aims to reduce the rate to 6.8 cases per100,000 persons. "Novel intervention strategies to reduce or eliminate salmonella infoods are a priority for food processors and researchers," wrote the authors of the new study, to be published in the Journal of Food Science. This is opening up new challenges for manufacturers to make safefoods that meet both the natural/organic and the food safetycriteria - and for food ingredient firms to offer them appropriateingredients to this end. The study, conducted at the Center for Food Safety-IFSE at theUniversity of Arkansas in the US, assessed seven citrus essentialoils for their antibacterial activity against 11 serotypes orstrains of salmonella using disc diffusion assay. "Essential oils from citrus offer the potential for all naturalantimicrobials for use in improving the safety of organic or allnatural foods," said the researchers. orange oil terpeneless; Valencia orange oil; cold pressed orangeterpenes; high purity orange terpenes; d-limonene; terpenes fromorange essence; and five-fold concentrated Valencia orange oil. Of these, orange terpenes, single-folded d-limonene, and orangeessence terpenes were all seen to inhibit salmonella activity.These were taken forward to establish their minimal inhibitoryconcentration (MIC) against the bacteria. The researchers found terpenes from orange essence to be the mostactive compound, with a MIC of between 0.125 per cent and 0.5 percent against the salmonella. In comparison, the orange terpenes and d-limonese had MICs of 1 percent. Finally, the team used mass chromatography mass spectrometryanalysis to establish the components of the terpenes from orangeessence. They were found to made up mostly of d-limonene (94 percent), and myrcene (about 3 per cent). "These citrus essential oils may provide help for foodmanufacturers to increase food safety while at the same time beingacceptable to consumers who prefer natural rather than syntheticantimicrobials in their food," concluded the team. For example, researchers from Miguel Hernandez University inAlicante in Spain reported in the journal Food Chemistry (onlineahead of print last month) that essential oils of lemon, mandarin,grapefruit and orange all exhibited antifungal activity against thecommon food moulds Aspergillus niger, Aspergillus flavus, Penicillium chrysogenum and Penicillium verrucosum.