研究目的
To quantify the total amount of carotenoids and chlorophylls' derivatives in virgin and extra-virgin olive oils using two near UV-Vis spectroscopic techniques and compare their results for practical applications in quality and authenticity assessment.
研究成果
The study found that the deconvolution method by Domenici et al. provides more accurate and reliable quantification of pigments compared to the method by Mínguez-Mosquera et al., which systematically underestimates values. There is a good linear correlation between the methods for chlorophyll derivatives but worse for carotenoids. The deconvolution method is recommended for not fresh olive oils due to its robustness and avoidance of sample treatment, supporting its use in fast quality assessment.
研究不足
The method by Mínguez-Mosquera et al. underestimates pigment concentrations and may not account for spectral overlaps. The deconvolution method neglects minor pigments and is not applicable to fresh olive oils containing chlorophylls. Both methods have limitations in precision for carotenoid quantification due to potential interferences.
1：Experimental Design and Method Selection:
The study compares two spectroscopic methods: one by Mínguez-Mosquera et al. (1990) using absorbance at specific wavelengths (670 nm and 470 nm) with oil diluted in cyclohexane, and another by Domenici et al. (2014) using mathematical deconvolution of the whole absorption spectrum of undiluted oil to quantify four main pigments.
2：Sample Selection and Data Sources:
Several Italian olive oil samples, including mono-cultivar and blends from Tuscany, harvested in 2012 and 2015, stored at controlled temperatures (room temperature or 4°C), were analyzed.
3：List of Experimental Equipment and Materials:
UV-vis spectrophotometer (Jasco V-550), quartz cells with optical paths of 1 cm and
4：5 cm, cyclohexane for dilution, olive oil samples. Experimental Procedures and Operational Workflow:
For the first method,
5：5 g of oil was diluted in cyclohexane to 25 mL, and absorbance was measured at 670 nm and 470 nm. For the second method, spectra of undiluted oil were recorded from 390 nm to 720 nm, and deconvolution was performed using a mathematical tool in Excel. All measurements were done in triplicate. Data Analysis Methods:
Concentrations were calculated using specific equations for each method. Statistical analysis included t-tests and least significant difference (LSD) tests at p ≤ 0.05, performed in Excel.
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