Near-Infrared (NIR) Spectroscopy: Rapid and Non-Destructive Analysis of Grain and Wheat Quality
Q.C. Food Engineer Selin Yolcu , Q.C. Food Engineer Gülperi Sıla Bardakçı
In recent years, the demand for fast, reliable, and environmentally friendly technologies in food production processes and analyses has been steadily increasing. Accordingly, various innovative technologies have been developed as alternatives to traditional methods. The dependence of traditional methods on equipment, chemical usage, and expert analysts, as well as their time-consuming nature, has boosted interest in these innovative solutions. Among these alternatives, Near-Infrared (NIR) Spectroscopy has emerged as a powerful and efficient technology.
Spectroscopy is the process of measuring and interpreting the electromagnetic radiation absorbed or emitted by atoms, molecules, or ions during transitions between their energy levels. In this context, spectroscopic analyses are instrumental methods that examine the properties of substances such as light absorption, transmission, or reflection.
NIR spectroscopy is based on the interaction of light with matter. Electromagnetic radiation in the wavelength range of 780-2500 nm induces molecular vibrations. Specifically, the vibrations of bonds such as O-H, N-H, and C-H provide information about the chemical and physical properties of grains. Near-Infrared (NIR) Spectroscopy correlates quality attributes of food samples with light absorption in a specific wavelength range of the electromagnetic spectrum. Analyses for interpreting this correlation have enabled the routine use of NIR technology in both physical and chemical analyses of food and agricultural products.
NIR Spectroscopy has become an indispensable part of modern quality control processes, especially in wheat and grain analysis. This technology provides the agriculture and food sectors with the ability to perform rapid and reliable analyses without the use of chemicals. Enhancing the efficiency of food safety and quality management, NIR devices can be utilized both in laboratory settings and in the field.
Key Components:
- Light Source: Generates infrared light and directs it to the sample.
- Sample Cell: Holds solid or liquid samples.
- Detector: Measures the reflected or transmitted light.
- Spectrometer: Produces the absorption spectrum.
- Software: Analyzes data and calculates chemical content and physical properties.
Analysis Process:
- Sample Preparation: Wheat grains or ground samples are placed in the sampling compartment of the device. The lack of special preparation makes the process highly practical.
- Spectral Scanning: Near-infrared light is directed at the sample. The light reflected or absorbed by the sample generates a spectrum based on its molecular structure.
- Calibration and Modeling: Using reference models created from previous laboratory tests, variations in the spectral data are analyzed.
- Result Interpretation: Quantitative results for parameters such as protein, moisture, gluten, and sedimentation index are reported within seconds.
In a study conducted with Bastak Instruments’ DA 9000 N.I.R Analyzer, wheat samples from various regions in Turkey were analyzed. Within seconds, parameters such as gluten content, protein content, moisture level, ash content, and Zeleny sedimentation values were measured.
With its intuitive 13” touchscreen, next-generation diode array sensor, and the ability to analyze both flour and grain using the same sample cup, the Bastak DA 9000 N.I.R Analyzer provided a fast and user-friendly experience. During the study, the physicochemical properties of wheat samples and the protein content of wheat genotypes were compared using the N.I.R method.
Figure 1: Series 1 represents protein values obtained using the Kjeldahl Method, while Series 2 represents protein values measured by FT-NIR.
Protein levels measured by the Kjeldahl method ranged from 10.21% to 16.34%, while those obtained using the NIR method fell within a range of 10.34% to 16.57% (Figure 1). Samples collected from different regions for the same wheat genotype showed varying levels of similarity between protein values obtained by the two methods.
The accuracy of the measurement results for both methods was found to be high (r = 0.91), indicating a strong correlation in the analysis. This demonstrates that NIR spectroscopy is a reliable method for determining protein content in wheat.
