Differences in optical properties of fruit tissues between stone fruits and citrus fruits

Abstract

Abstract Stone fruits have a single-core, and the core volume is large, located in the center of the fruit. In the process of transmission and reflection spectroscopic detection, the influence of fruit core on light cannot be ignored when light passes through flesh. Analyzing the difference in optical characteristics between stone fruits and citrus fruits tissues can provide a theoretical basis for the design of a reasonable optical detection device. It is of great significance for the optical detection of fruit quality. In this paper, a self-developed near-infrared diffuse reflection optical fibre probe with multi-point emission and multi-point reception is used to collect the diffuse reflection spectra of peach and navel orange, and compare the spectral characteristics of the two fruits. The spectral energy of peach is about twice as strong as the spectral energy of navel orange between 600\xa0nm and 900\xa0nm. Preprocess the spectral data with preprocessing methods to reduce the influence of noise and stray light. Compare the partial least squares (PLS) regression models of peach and navel orange. Experiments show that the results of using the baseline correction preprocessing method are all the best. The prediction correlation coefficient (Rp) of the peach is better than that of the navel orange and the root mean square error of the prediction (RMSEP) is also lower. The Rp of peach reached 0.92, and RMSEP was 0.32°Brix. It turned out that after light enters the fruit tissues, part of the light will be reflected out of the fruit when it encounters the core of the fruit. Therefore, in the diffuse reflection detection mode, stone fruits can receive more light and the spectral energy will be stronger than that of citrus fruits.