A guide for quality control of honey: Application of UV–vis scanning spectrophotometry and NIR spectroscopy for determination of chemical profiles of floral honey produced in southern Brazil

Abstract

This study aimed to determine the chemical profile of floral honey by ultraviolet and visible spectrophotometry (UV–vis) and near-infrared (NIR) vibrational spectroscopy, and via analysis of the total phenolic content, considering the harvest year (2018–2019 and 2019–2020), geographic and botanical origins, and seasonality of samples (n = 116) collected in southern Brazil. The total phenolic content (TPC) of honey showed great variation by geographic origin and for both harvests, with a higher overall average in the 2019–2020 (3.81–7.22 mg/mL) compared to the 2018–2019 (2.49–6.17 mg/mL), which seemed to be related to climatic factors, mainly precipitation. The visual inspection of the UV–vis spectra (280–320 nm) revealed two samples with distinct chemical compositions, being these further confirmed as outlier by PCA. UV–vis (260–360 nm) coupled to PCA was able to distinguish honey with higher and lower TPC. The NIR spectral data set revealed discrepancies among honey according to the harvest seasons, with bands associated with higher water content and lower carbohydrate amounts in the 2018–2019-collected samples; the contrary has been noted for the 2019–2020. Thus, UV–vis and NIR spectroscopies coupled to PCA proved to be a useful approach to distinguish honey samples as to possible adulterations and geographic origin associated with their higher and lower phenolic contents.