Abstract: Citrus is the world’s most produced fruit. China is a big producer and seller of citrus. At present, there are some problems in China’s citrus industry, such as poor separation and processing technologies and backward postharvest postharvest quality grading, making citrus fruit from the country uncompetitive in the international market. The detection and quality grading of citrus products is an effective way to improve their competitiveness. However, traditional quality evaluation methods, such as naked eye observation, image recognition and chemical titration, are time-consuming, laborious, and inaccurate. Particularly, chemical titration is destructive to samples. Therefore, developing a fast and non-destructive detection method for citrus fruit quality is a hotspot and difficulty in current research. In recent years, near-infrared spectroscopy (NIRS) has been widely used in the non-destructive analysis of environmental, medicinal and food samples. However, there are still some problems in the non-destructive testing of citrus fruit by NIRS, such as unclear mechanism and low precision. Researchers from China and other countries have made many efforts to solve those problems. In this article, the literature on non-destructive detection of citrus using NIRS is reviewed, with focus on the feasibility of using NIRS to detect citrus fruit as well as the selection and chemometric optimization of instrument types and parameters. And some suggestions are put forward to solve problems existing in this field. We expect that this review will provide reference for the nondestructive detection of citrus fruit.

Key words: near-infrared spectroscopy; citrus; non-destructive detection; chemometrics