著者

Ali Reza Fardin-Kia Sanjeewa R. Karunathilaka Betsy Jean Yakes Kyungeun Lee Zachary Ellsworth Lea Brückner Magdi M. Mossoba

出版者

Japan Oil Chemists' Society

雑誌

Journal of Oleo Science (ISSN:13458957)

巻号頁・発行日

vol.68, no.11, pp.1105-1112, 2019 (Released:2019-11-07)

参考文献数

29

被引用文献数

5

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We recently observed that the weak near-infrared (NIR) band near 5260 cm–1 was relatively more intense for extra virgin olive oil (EVOO) than for refined olive oil (ROO). We also observed that its intensity was diminished upon heating and erroneously presumed that it may be attributed to volatile carbonyl components in EVOO. In the present study we demonstrate for the first time that this band is primarily attributed to a water O-H combination band. To accurately determine the intensity of this weak band, observed on a shifted and sloping baseline, we measured the peak-to-peak (p-p) height of its first derivative. An exponential calibration curve for p-p height versus gravimetrically-determined concentration of spiked water was satisfactorily generated. The calibration curve was first evaluated by using independent sets of gravimetrically prepared test samples. Subsequently, it was used to determine the moisture content, a quality parameter, for a limited set of authenticated reference olive oils whose quality and purity were confirmed by official methods. These concentrations, 0.098-0.12% H2O (w/w) for EVOO, 0.022-0.030% H2O (w/w) for ROO, and 0.028-0.054% H2O (w/w) for pomace olive oil (POO), were consistent with those reported in the literature. For 88 commercial products investigated, the moisture levels fell in the range from 0.026% to 0.13% (w/w). The correlation between moisture content and other olive oil quality parameters has been reported in the literature and has yet to be further investigated.