Nondestructive determination of carotene contents in leaf vegetables by fiber-optics spectroscopy

摘要

To develop an non-destructive method to evaluate nourishment and freshness of leaf vegetables, visible spectroscopy using 3 kinds of fiber optics was used to estimate the carotene contents in 4 kinds of leaf vegetables. (1) The spectra of the leaves of vegetables were measured with there times with 3 kinds of fiber optics in the transmittance mode, the reflectance mode and the interactance mode. The carotene were measured by the HPLC method. Multiple regression analysis was carried out to relate the carotene contents to the first spectral data by three mode. The coefficients to determine the carotene contents with spectral data in transmittance mode, absorbance, reflectance mode and interactance mode were 0.664, 0.773, 0.728, 0.377, respectively. Absorbance and reflecance data were suitable to estimate the carotene contents of leaf vegetables. (2) Suitable wavelengths for estimation of carotene contents were studied with the relation of the spectra for carotene and chlorophyl standards. (3) Absorbance and reflectance spectra were divided into a calibration set and a prediction set, and the predicting equations were constructed using calibration sets respectively. The carotene contents of samples in the prediction set were estimated by the predicting eqations. As a result, the prediction equation constructed using reflectance spectra gave the highest prediction. The coefficients of determination using reflectance spectra were 0.65 and the standard error of prediction was 420. It was suggested by neans of visible spectroscopy using fiber optics it is possible to estimate carotene contents in leaf vegetables.