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NIR detection of honey adulteration reveals differences in water spectral pattern

Bázár, György, Romvári, Róbert, Szabó, András, Somogyi, Tamás, Éles, Viktória, Tsenkova, Roumiana
Food chemistry 2016 v.194 pp. 873-880
Robinia, absorption, adulterated products, chemical structure, fiber optics, high fructose corn syrup, honey, least squares, near-infrared spectroscopy, sugars, traditional technology
High fructose corn syrup (HFCS) was mixed with four artisanal Robinia honeys at various ratios (0–40%) and near infrared (NIR) spectra were recorded with a fiber optic immersion probe. Levels of HFCS adulteration could be detected accurately using leave-one-honey-out cross-validation (RMSECV=1.48; R2CV=0.987), partial least squares regression and the 1300–1800nm spectral interval containing absorption bands related to both water and carbohydrates. Aquaphotomics-based evaluations showed that unifloral honeys contained more highly organized water than the industrial sugar syrup, supposedly because of the greater variety of molecules dissolved in the multi-component honeys. Adulteration with HFCS caused a gradual reduction of water molecular structures, especially water trimers, which facilitate interaction with other molecules. Quick, non-destructive NIR spectroscopy combined with aquaphotomics could be used to describe water molecular structures in honey and to detect a rather common form of adulteration.