Determination of Antioxidant Capacities, α-Dicarbonyls, and Phenolic Phytochemicals in Florida Varietal Honeys Using HPLC-DAD-ESI-MSn
2014
Honeys contain phenolic compounds and α-dicarbonyls with antioxidant and antimicrobial capacities, respectively. The type and concentration of these compounds vary depending on the floral source and geographical location where the honey is produced. Seventeen varietal honeys, including 12 monofloral and 5 multifloral honeys, were sampled from different regions of Florida. The monofloral honeys included those from citrus, tupelo, palmetto, and gallberry. These honeys were evaluated for their antioxidant capacity, total phenolic content, and free radical scavenging capacity and compared with three New Zealand Manuka honeys. Phenolic phytochemicals and α-dicarbonyls were identified and quantified using HPLC-DAD-MSn. Several honey varieties from gallberry, Manuka, and multifloral displayed a total phenolic content >1000 μg GAE/g. A citrus honey had the lowest total phenolic content of 286 μg GAE/g. The oxygen radical absorbance capacity of the honeys ranged from 1.48 to 18.2 μmol TE/g. All honeys contained 3-deoxyglucosone at a higher concentration than methylglyoxal or glyoxal. Manuka honeys had higher concentrations of methylglyoxal than other varieties. Plant hormones 2-cis,4-trans-abscisic acid and 2-trans,4-trans-abscisic acid were the most abundant phytochemicals in all honeys. Coumaric acid, rutin, chrysin, pinocembrin, quercetin, luteolin, and kaempferol were also found in samples but at lower concentrations.
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