Determination of Antioxidant Capacities, α-Dicarbonyls, and Phenolic Phytochemicals in Florida Varietal Honeys using HPLC-DAD-ESI-MSn
J Agric Food Chem, 2014 Aug 7
Honeys contain phenolic compounds and α-dicarbonyls with antioxidant and anti-microbial 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 multi-floral honeys were sampled from different regions of Florida. The monofloral honeys included those from citrus, tupelo, palmetto, 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 multi-floral displayed a total phenolic content above 1000 µg GAE/ml. A citrus honey had the lowest total phenolic content of 286 µg GAE/ml. The Oxygen Radical Absorbance Capacity of the honeys ranged from 1.48-18.2 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 hormone 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 with lower concentrations.