Classification and Characterization of Manuka Honeys Based on Phenolic Compounds and Methylglyoxal
J Agric Food Chem, 2012 Jun 7
Manuka honey from New Zealand is often considered a medicinal product of special value due to its high level of antimicrobial activity. Therefore, the distinct authentication of its botanical origin is of great importance.
In this respect, it is particularly the analysis especially phenolic acids, flavonoids, and norisoprenoids which are described as useful aside of the common pollen analysis.
In the present study numerous manuka honeys were analysed by UPLC-PDA-MS/MS after solid phase extraction and compared to other kinds of honey in order to define marker substances characteristic for manuka honeys.
The PDA-profiles obtained notedly differed from each other so that individual honey samples could be assigned to three groups.
In this, typical for the honeys of Group 1 were the comparably high concentrations of 4-hydroxybenzoic acid, dehydrovomifoliol, and benzoic acid whereas the profiles of
Group 2 showed high kojic acid and 2-methoxybenzoic acid intensities.
Characteristic for the manuka honeys of Group 3 were high syringic acid, 4-methoxyphenyllactic acid, and methyl syringate yields. Furthermore, the comprehensive comparison of manuka honeys to other unifloral honeys revealed that especially kojic acid, 5-methyl-3-furancarboxylic acid, 3,4,5-trimethoxybenzoic acid esterified with maltose, unedone, 2-methoxybenzoic acid, 4-methoxyphenyllactic acid, 3-hydroxy-1-(2-methoxyphenyl)-penta-1,4-dione, and methyl syringate are useful for distinguishing manuka honeys from the other kinds of investigated honey.
Moreover, kojic acid, unedone, 3-hydroxy-1-(2-methoxyphenyl)-penta-1,4-dione, 5-methyl-3-furancarboxylic acid, 3-hydroxy-1-(2-methoxyphenyl)-penta-1,4-dione, and lumichrome were identified in manuka honey for the first time.