ABSTRACT
Experiment was carried out to explore the light intensity change inside citrus samples in the present study. An experimental platform was set up, including a light box, a spectrometer, a sample stage, an optic fiber probe, light sources, etc. The sample stage is adjustable in three dimensions. The optic fiber probe was used to measure the light changes by observing the light attenuation and intensity variation within the citrus tissues. A 632 nm laser source and a 50 W tungsten halogen lamp light source were used. Light intensity and transmittance were investigated at different positions within the citrus fruit. The band with most significant intensity difference was selected to analyze the light intensity and transmittance trends in different positions inside the citrus fruit In order to examine the influence significance of the sample factor on test results, SPSS software was used to do the analysis of variation (ANOVA) of different samples. The results showed that light intensity and transmittance have a positive correlation with puncture depth, while citrus peel and stone have a more obvious attenuation effect than citrus flesh, and the influence of the sample factor on the test results is not significant. Further research can be carried out by improving the experimental device. The method used and results obtained in this study are valuable for studies on light transmission properties inside fruit tissue, not only for citrus but also for other kinds of fruits.
Subject(s)
Citrus , Fruit , Light , Fiber Optic TechnologyABSTRACT
The objective of the present research was to study the influence of four kinds of light intensity of near-infrared diffuse reflectance spectra on the determination of pear soluble solids content. Qualitative analysis of the four spectra showed that the differences between them were too slight to find. After further analysis by principal component regression (PCR), stepwise multiple linear regression (SMLR) and partial least squares regression (PLSR) as well as comparisons among them, the results of PCR model and SMLR models which had low correlation coefficients (r) were worse than those of PLSR model. The model based on PLSR was further optimized by the second order derivative pretreatments of the spectra, and its correlation coefficients ranged from 0.947 to 0.970. The relative coefficients in PLSR model based on spectra from four sets were 0.958. The results indicate that light intensity has little influence on the determination of pear soluble solids content based on near-infrared diffuse reflection spectra.
