Review: Application and research progress of near infrared spectroscopy for multidimensional assessment of coffee beans

Near infrared spectroscopy (NIR), recognized as a rapid, non-invasive, easy-to-operate and cost-effective tool for substance analysis, has been widely used and intensively researched in the field of coffee bean analysis. From the perspective of multidimensional evaluation (physical assessment of green coffee, extrinsic assessment, descriptive assessment and affective assessment), this review systematically explores the current applications of near infrared spectroscopy in characterizing the attributes of Arabica coffee beans, and further investigates the identification of coffee bean adulteration and chemical properties through an exhaustive survey of more than 90 published, peer-reviewed articles. Building upon this foundation, this review analyzes and discusses the roles of chemometrics, spectral preprocessing methods, characteristic wavelength screening strategies and outlier removal methods. Through the combined application of these methods, the optimal NIR spectral inversion mechanisms corresponding to different coffee bean properties are revealed. This body of research not only highlights the substantial potential of near infrared spectroscopy but also pinpoints the pressing research gaps within the industrial process of coffee bean quality control. Currently, few studies have differentiated processing methods and elucidated the sweetness attributes, grading attributes, and flavor descriptors of coffee beans. Looking ahead, near infrared spectroscopy technology is anticipated to driving the establishment of a comprehensive and objective coffee bean value system.