Characterization of Brazilian monofloral and polyfloral honey by UHPLC-MS and classic physical-chemical analyses

Fifty samples of honey, reported by the suppliers as being: orange (Citrus sinensis), eucalyptus (Eucalyptus spp.), coffee (Coffea Arabica), cipo uva (Cissus rhombifolia), quince (Cydonia oblonga), monjoleiro (Acacia polyphylla), mangrove and honeydew were collected from different states of Brazil, between 2014 and 2016, with the aim of studying their physical-chemical properties and chemical composition, searching for markers to determine their floral origin, authenticity, and quality. There is little information on some of these types of honey, such as quince honey, whose chemical characteristics were defined in the present study. Thus, the total phenolic and flavonoid contents, proteins, color, moisture, and electrical conductivity were evaluated. All the samples presented satisfactory results for color and percentage of sugars in relation to the Brazilian legislation, as well as protein concentration; most were within the limit of conductivity established by the Council of the European Union. Only six samples indicated a probability of overheating, having high HMF values. Phenolic compounds were extracted, analyzed by ultra-high-performance liquid chromatography with mass spectrometry and the data extracted and treated by chemometrics. Honey samples classified as quince by the producers were predominantly monofloral and had a distinct chemical marker; abscisic acid. Some of the samples declared as orange and coffee were clearly grouped, however, some samples declared as eucalyptus, coffee, and orange honey were probably not monofloral. Eucalyptus honey had high total phenolics and flavonoids, thus probably has a higher antioxidant function when compared to the other floral origins analyzed herein.