Regional, Annual, and Individual Variations in the Dihydroxyacetone Content of the Nectar of Ma̅nuka (Leptospermum scoparium) in New Zealand

Abstract

A method was designed and validated for the analysis of dihydroxyacetone in the floral nectar of ma̅nuka (Leptospermum scoparium). The method was applied to samples collected from different regions of the North Island and the Nelson region of the upper South Island of New Zealand during the period 2009-2012 as well as to nectar samples from some Australian Leptospermum species. The ratio of dihydroxyacetone to total sugar (DHA/Tsugar) was classified as low (<0.001 mg/mg), moderate (0.001-0.002 mg/mg), or high (>0.002 mg/mg). Inter- and intraregional variation were observed as well as interannual variation with variation from low to high classification occurring within one region and from low to moderate between years. Australian species also demonstrated elevated levels of dihydroxyacetone in the nectar. Some garden cultivars were shown to produce very high nectar DHA/Tsugar, and a survey of cultivars was undertaken; cultivars with single-flowered red or pink flowers were the most common producers of very high nectar DHA/Tsugar.

Discrimination of botanical origins for Chinese honey according to free amino acids content by high‐performance liquid chromatography with fluorescence detection with chemometric approaches

“…The price of honey varies widely because its quality depends on its chemical composition and botanical origin. For example, linden honey from China and manuka honey from New Zealand are considerably more expensive than other honeys . With such price variation, honey products are subject to illegal adulteration, mislabeling and misleading statements about their origin .…”

“…For example, linden honey from China and manuka honey from New Zealand are considerably more expensive than other honeys. 7 With such price variation, honey products are subject to illegal adulteration, mislabeling and misleading statements about their origin. 8,9 This dishonesty not only harms the interests of consumers, but also disrupts the normal order of the honey market.…”

WITHDRAWN: Development of a robust method for propagation of Leptospermum scoparium J.R.Forst. &amp; G.Forst. from semi-hardwood cuttings

“…However, to determine if the qualities of elite lines are reliably maintained beyond cutting propagation, further eld testing is necessary. Research on the species suggests that DHA:Tsugar levels in the nectar are maintained through clonal propagation (2) but slight variations in concentrations occur depending on the environment, soil and year (2,9).…”

“…Leptospermum scoparium (Manuka) honey has non-hydroxide antibacterial properties largely due to the presence of methylglyoxal (MGO) (5). The precursor to MGO is dihydroxyacetone (DHA) and is found in the nectar of L. scoparium plants (6)(7)(8)(9). Plants with high DHA to total sugars (DHA:Tsugar), in the nectar, are believed to produce honeys with the highest MGO concentration (6,7).…”

Chemical profiles of honeys originating from different floral sources and geographic locations examined by a combination of three extraction and analysis techniques

“…However, DHA has to-date only been found in Leptospermum nectar [11]. This suggests that a low level of honey originating from the Manuka floral type has been mixed with the Leatherwood honeys either during bee foraging or honey processing.…”