Determination of Fruit Oil Content and Fatty Acid Composition in Symplocos paniculata Using Near-infrared Reflectance Spectroscopy

Symplocos paniculata is an important a shrub or small tree with high fruit oil content that can be used as potential feedstocks for biodiesel and cooking oil production. The feasibility of using Near-Infrared Reflectance Spectroscopy (NIRS) at the wavelength ranger of 950-1650 nm for rapid and nondestructive determination of the fruit oil content and fatty acid composition of S. paniculata was investigated. Fruits were collected from 124 plants grown at different habitats in Hunan province. All fruits were air-dried and then scanned using NIRS. The fruit oil content and fatty acid composition were also analyzed using chemical method including hexane extraction and gas chromatography. The raw spectra were pretreated using four chemometrics such as 1^st and 2^st Derivative, Standard Normal Variate Transformation, Savitzky-Golay Smoothing, and Multiplicative Scatter Correction and then used for establishing calibration models. Partial Least Squares regression was used to develop the calibration equations for oil content and individual fatty acids such as palmitic acid, stearic acid, oleic acid, linoleic acid, and linolenic acid. External and cross-validation was conducted to test the reliability and accuracy of the calibration equations. The coefficients of determination (R²) in cross validation were 0.96, 0.90, 0.71, 0.91, 0.91, and 0.73, respectively. The residual prediction deviations were 3.5, 2.9, 2.8, 3.1, 2.3, and 2.6, respectively. These results indicated that NIRS successfully predicted the oil content and determined the composition of palmitic acid, stearic acid, oleic acid, linoleic acid, and linolenic acid. In conclusion, the NIRS model has great potential in the nondestructive determination of the fruit oil content and fatty acid composition of S. paniculata.