title: Investigating C-4 sugar contamination of manuka honey and other New Zealand honey varieties using carbon isotopes.
abstract: Carbon isotopes (δ(13)C honey and δ(13)C protein) and apparent C-4 sugar contents of 1023 New Zealand honeys from 15 different floral types were analyzed to investigate which New Zealand honey is prone to failing the AOAC 998.12 C-4 sugar test and evaluate the occurrence of false-positive results. Of the 333 honey samples that exceeded the 7% C-4 sugar threshold, 324 samples of these were New Zealand manuka honey (Leptospermum scoparium, 97.2% of all fails found in the study). Three monofloral honeys (ling, kamahi, and tawari) had nine samples (2.8% of all fails found in the study) with apparent C-4 sugars exceeding 7%. All other floral types analyzed did not display C-4 sugar fails. False-positive results were found to occur for higher activity New Zealand manuka honey with a methylglyoxal content >250 mg/kg or a nonperoxide activity >10+, and for some ling, kamahi and tawari honeys. Recommendations for future interpretation of the AOAC 998.12 C-4 sugar method are proposed.
authors.affiliation: National Isotope Centre, GNS Science, 30 Gracefield Road, Lower Hutt 5040, New Zealand.
authors.forename: Karyne M
authors.initials: KM
authors.lastname: Rogers
authors.forename: Mike
authors.initials: M
authors.lastname: Sim
authors.forename: Simon
authors.initials: S
authors.lastname: Stewart
authors.forename: Andy
authors.initials: A
authors.lastname: Phillips
authors.forename: Jannine
authors.initials: J
authors.lastname: Cooper
authors.forename: Cedric
authors.initials: C
authors.lastname: Douance
authors.forename: Rebecca
authors.initials: R
authors.lastname: Pyne
authors.forename: Pam
authors.initials: P
authors.lastname: Rogers
mesh_terms: D002241:Carbohydrates / Q000032:analysis*; D002247:Carbon Isotopes / Q000032:analysis*; D005504:Food Analysis / Q000379:methods / Q000592:standards; D005506:Food Contamination / Q000032:analysis*; D006722:Honey / Q000032:analysis* / Q000145:classification; D009520:New Zealand
chemical_list: D002241:Carbohydrates; D002247:Carbon Isotopes