Classification of Unifloral Honeys from SARDINIA (Italy) by ATR-FTIR Spectroscopy and Random Forest.

Nowadays, the mislabeling of honey floral origin is a very common fraudulent practice. The scientific community is intensifying its efforts to provide the bodies responsible for controlling the authenticity of honey with fast and reliable analytical protocols. In this study, the classification of various monofloral honeys from Sardinia, Italy, was attempted by means of ATR-FTIR spectroscopy and random forest. Four different floral origins were considered: strawberry-tree (Arbutus Unedo L.), asphodel (Asphodelus microcarpus), thistle (Galactites tormentosa), and eucalyptus (Eucalyptus calmadulensis). Training a random forest on the infrared spectra allowed achieving an average accuracy of 87% in a cross-validation setting. The identification of the significant wavenumbers revealed the important role played by the region 1540-1175 cm-1 and, to a lesser extent, the region 1700-1600 cm-1. The contribution of the phenolic fraction was identified as the main responsible for this observation.

Chemometric treatment of simple physical and chemical data for the discrimination of unifloral honeys.

In this work, nonspecific physico-chemical parameters were determined in 160 honey samples belonging to the four main botanical categories present in Sardinia Island, Italy (strawberry tree, thistle, asphodel and eucalyptus) in order to develop a discriminant method for determining the botanical origin of honey. All the possible combinations of the seven physico-chemical parameters (pH, free acidity, electrical conductivity, color, total phenolic compounds, FRAP activity, and DPPH activity) measured in the honey samples were evaluated by Linear Discriminant Analysis (LDA). LDA models led to the prediction of each botanical origin with a very low level of misclassification (typically less than 5%). Since very high levels of correct prediction in cross validation (98.3%) and external validation (100%) were obtained considering only four parameters (i.e. pH, acidity, conductivity and DPPH), these results might allow a fast and easy control of the botanical origin of honeys.