title: Microbial inhibitory and radical scavenging activities of cold-pressed terpeneless Valencia orange (Citrus sinensis) oil in different dispersing agents.
abstract: BACKGROUND
  Due to their low solubility in water, oil-based bioactive compounds require dispersion in a surface-active agent or appropriate solvents to ensure maximum contact with microorganisms. These combinations, however, may change their physical and/or chemical characteristics and consequently alter the desired functionality. The objective of this study was to determine the impact of selected dispersing agents, ethanol, dimethyl sulfoxide (DMSO), and Tween-80, on cold-pressed terpeneless (CPT) Valencia orange oil to function as a free radical scavenger and an antimicrobial food additive.
  
  
  RESULTS
  When dissolved in ethanol or DMSO, the orange oil fraction had similar minimum inhibitory concentrations (MIC) for Listeria monocytogenes ATCC 19 115 (0.3% and 0.25% v/v respectively), which were significantly lower (P <or= 0.5) than the MIC for Salmonella typhimurium ATCC 14 028 (1% v/v). Both ethanol and DMSO oil dispersion systems exhibited an intermediate MIC (0.75% v/v) for Lactobacillus plantarum WCFS1. The orange oil (up to 3%) in an aqueous solution of 0.1% Tween-80 yielded no inhibitory activities against any of the test bacteria. However, the 1% natural orange oil dispersed in Tween-80 exhibited 56.86% 2,2-diphenyl-1-picryl hydrazyl (DPPH) radical inhibition versus 18.37% and 16.60% when the same level of orange oil was dissolved in DMSO or ethanol, respectively. At the same orange oil concentration, the oil/Tween-80 suspension yielded 57.92% neutralization of hydroxyl radicals. This represents 71.37% of the mannitol antioxidant activity, which was used as a positive control.
  
  
  CONCLUSIONS
  These findings suggest that Tween-80 is an appropriate dispersing agent only if the antioxidant functionality is desired. If both antimicrobial and antioxidant properties are needed, the CPT Valencia orange oil should be dispersed in either DMSO or ethanol.
authors.affiliation: Center for Food Safety-IFSE and Department of Food Science, University of Arkansas, Fayetteville, AR 72704, USA.
authors.forename: Vesela I
authors.initials: VI
authors.lastname: Chalova
authors.forename: Philip G
authors.initials: PG
authors.lastname: Crandall
authors.forename: Steven C
authors.initials: SC
authors.lastname: Ricke
mesh_terms: D000890:Anti-Infective Agents / Q000737:chemistry / Q000494:pharmacology*; D001713:Biphenyl Compounds / Q000737:chemistry; D049109:Cell Proliferation / Q000187:drug effects; D032084:Citrus sinensis / Q000737:chemistry*; D053138:Cyclohexenes / Q000032:analysis; D004121:Dimethyl Sulfoxide / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D045703:Emulsifying Agents / Q000737:chemistry*; D000431:Ethanol / Q000737:chemistry; D005503:Food Additives / Q000737:chemistry / Q000494:pharmacology; D005511:Food Handling; D016166:Free Radical Scavengers / Q000737:chemistry / Q000494:pharmacology*; D005638:Fruit / Q000737:chemistry; D017665:Hydroxyl Radical / Q000737:chemistry; D048191:Lactiplantibacillus plantarum / Q000187:drug effects; D000077222:Limonene; D008089:Listeria monocytogenes / Q000187:drug effects; D008826:Microbial Sensitivity Tests; D010851:Picrates / Q000737:chemistry; D010938:Plant Oils / Q000737:chemistry* / Q000494:pharmacology*; D011136:Polysorbates / Q000737:chemistry; D012486:Salmonella typhimurium / Q000187:drug effects; D012995:Solubility; D013729:Terpenes / Q000032:analysis; D013997:Time Factors
chemical_list: D000890:Anti-Infective Agents; D001713:Biphenyl Compounds; D053138:Cyclohexenes; D045703:Emulsifying Agents; D005503:Food Additives; D016166:Free Radical Scavengers; D010851:Picrates; D010938:Plant Oils; D011136:Polysorbates; D013729:Terpenes; D017665:Hydroxyl Radical; D000431:Ethanol; D000077222:Limonene; C087245:orange oil; C004931:1,1-diphenyl-2-picrylhydrazyl; D004121:Dimethyl Sulfoxide