Determination of Polarimetric Parameters of Honey by Near-Infrared Transflectance Spectroscopy

Abstract

NIR transflectance spectroscopy was used to determine polarimetric parameters (direct polarization, polarization after inversion, specific rotation in dry matter, and polarization due to nonmonosaccharides) and sucrose in honey. In total, 156 honey samples were collected during 1992 (45 samples), 1995 (56 samples), and 1996 (55 samples). Samples were analyzed by NIR spectroscopy and polarimetric methods. Calibration (118 samples) and validation (38 samples) sets were made up; honeys from the three years were included in both sets. Calibrations were performed by modified partial least-squares regression and scatter correction by standard normal variation and detrend methods. For direct polarization, polarization after inversion, specific rotation in dry matter, and polarization due to nonmonosaccharides, good statistics (bias, SEV, and R(2)) were obtained for the validation set, and no statistically (p = 0.05) significant differences were found between instrumental and polarimetric methods for these parameters. Statistical data for sucrose were not as good as those of the other parameters. Therefore, NIR spectroscopy is not an effective method for quantitative analysis of sucrose in these honey samples. However, NIR spectroscopy may be an acceptable method for semiquantitative evaluation of sucrose for honeys, such as those in our study, containing up to 3% of sucrose. Further work is necessary to validate the uncertainty at higher levels.

Analytical Methods Used in the Quality Control of Honey

“…21,59 Polarimetric properties of honey (direct polarization, polarization after inversion, polarization due to nonmonosaccharides, and specific rotation in dry matter) have been successfully calibrated using NIR spectroscopy. 60 The determination of the specific rotation can be used for the differentiation between honeydew honeys and blossom honeys. Most of the honeydew honeys are dextrorotatory, whereas nectar honeys are levorotatory.…”

The Use of Visible and near Infrared Spectroscopy to Classify the Floral Origin of Honey Samples Produced in Uruguay

“…[1][2][3] The analysis of both the gross composition (moisture, pH, sugars, colour and hydroxy methyl furfuraldehyde) and the adulteration of honey using NIR spectroscopy has been examined and reported elseshwere. [20][21][22][23][24][25][26][27] The use of NIR spectroscopy combined with chemometric methods has also been reported recently to identify the botanical origin of honey produced in the European Community. 14 The aim of this work was to investigate the potential of visible (vis) and NIR spectroscopy as a rapid and low cost technique to classify honey samples from Uruguay (South America) according to their fl oral origin.…”

Honeydew Honeys: A Review on the Characterization and Authentication of Botanical and Geographical Origins

“…Honeydew and adulterated honeys are generally dextrorotatory, whereas blossom honeys are levorotatory. 20 Honeydew honeys also have higher oligosaccharide contents, including mainly melezitose and raffinose, and lower contents of monosaccharides than blossom honeys. 18 Melezitose (a trisaccharide) is considered a distinguishing feature of honeydew honeys.…”

“…Its specific optical rotation depends to a large extent on the types and relative amounts of carbohydrates present in the honey. Honeydew and adulterated honeys are generally dextrorotatory, whereas blossom honeys are levorotatory …”