Leptosperin is a distinct and detectable fluorophore in Leptospermum honeys. (1st January 2017)

• Record Type: Journal Article
• Authors: Bong, Jessie; Prijic, Gordana; Braggins, Terry J.; Schlothauer, Ralf C.; Stephens, Jonathan M.; Loomes, Kerry M.
• Is Part Of: Food chemistry. Volume 214(2017)
• Page Start: 102
• Page End: 109
• Publication Date: 2017-01-01
• Subjects: Leptosperin -- Methyl syringate -- Manuka (Leptospermum scoparium) -- Leptospermum -- Fluorescence; Food -- Analysis -- Periodicals; Food -- Composition -- Periodicals; 664
• DOI: 10.1016/j.foodchem.2016.07.018
• Languages: English
• ISSNs: 0308-8146

Abstract

Highlights: Leptosperin is responsible for the unique MM1 fluorescence marker in manuka honey. There is a quenching effect from the honey matrix on leptosperin fluorescence. Leptosperin is chemically stable in honey over prolonged storage at 37 °C. L. subtenue had trace levels of leptosperin compared to other Leptospermum species. Fluorescence spectroscopy offers a method for authenticating Leptospermum honey. Abstract: New Zealand manuka ( Leptospermum scoparium ) honey exhibits two unique fluorescence signatures that distinguish it from other honey types. One of these is the MM1 fluorescence marker (270–365 nm excitation–emission) which we show is due to a Leptospermum nectar-derived compound, leptosperin. Synthetic or honey-purified leptosperin not only displayed an identical fluorescence spectrum, but supplementation of leptosperin into clover or artificial honeys generated the MM1 fluorescence signature. There was a quenching effect of the honey matrix on leptosperin fluorescence but otherwise leptosperin was chemically stable over prolonged storage at 37 °C. Leptosperin was also present in the woody-fruited Australian Leptospermum species at elevated concentrations but virtually absent in Leptospermum subtenue suggesting its elevated expression developed following the mid-Miocene separation of the genus. These findings suggest that fluorescence spectroscopy could offer a rapid and high-throughput screening method for identification of Leptospermum honeys using the MM1 fluorescence marker.