Miniaturized Near‐Infrared Spectroscopy – The Ultimate Analytical Tool in Food and Agriculture

Abstract Near‐infrared (NIR) spectroscopy is widely used in qualitative and quantitative analysis in various fields of applications. Compared to conventional methods of analytical chemistry, NIR spectroscopy offers many practical advantages in terms of speed, efficiency, minimal (or no) requirements for sample preparation, and the applicability to many types of samples. In the past decade, the technology of portable NIR spectrometers has rapidly advanced, which enabled new applications of this technique in science and industry where the capacity to perform spectral analysis directly on site is the key advantage. Miniaturization introduced NIR spectroscopy to practical use in analytical scenarios that were unattainable for standard laboratory equipment. The advantages of miniaturized NIR spectroscopy are particularly evident in several areas where fast and nondestructive on‐site analysis is essential – e.g. natural products and resources, and agri‐food items in particular. The sample types commonly focused in these applications are characterized by chemical complexity and diversity depending on the geographic origin, conditions of cultivation and/or storage, or harvest time. Miniaturization necessitated different engineering solutions that introduced wide diversity in the elements used for construction of portable spectrometers. Consequently, the applicability of these instruments and their performance in a given application attract keen attention. Intensive studies are devoted to method development and evaluation of miniaturized NIR sensors in a variety of analytical problems. This article discusses the essential topics related to fundamentals and applications of miniaturized NIR spectrometers, with an emphasis on practical applications in food and agriculture sectors. However, an overview of the design principles of portable NIR instruments and their relationships with analytical figures of merit are provided as well in an attempt to draw a comprehensive picture of the state‐of‐the‐art and future potential of this increasingly influential analytical technique.