Analysis of Moisture Content, Total Oil and Fatty Acid Composition by NIR Reflectance Spectroscopy: A Review

Near Infrared (NIR) Reflectance spectroscopy has established itself as an important analytical technique in the field of food and agriculture. It is quicker and easier to use, and does not require processing the samples with corrosive chemicals such as acids or hydroxides. However, in earlier times, the samples had to be ground into powder form before making any measurements. Thanks to the development of new soft ware packages for use with NIR instruments, NIR techniques could be used in the analysis of intact grains and seeds. While most of the commercial instruments presently available work well with small grain size materials such as wheat and corn, they were found to be unsuitable for large kernel size products such as shelled or in-shell peanuts. In this chapter, principles of NIR Reflectance spectroscopy were reviewed, in particular reference to the water and oil bands. Also presented are some recent applications of NIR for the rapid and nondestructive measurement of moisture and total oil contents in shelled and in-shell peanuts. Applicability, and limitations of NIR reflectance method in the analysis of fatty acid composition of different varieties of peanuts while they are in their shells was also discussed. Ability to rapidly and nondestructively measure the water and total oil content, and analyze the fatty acid composition, will be immensely useful in the grading process of grains and nuts.