A single analytical platform for the rapid and simultaneous measurement of protein, oil and beta glucan contents of oats using Near Infrared Reflectance Spectroscopy

Abstract

Effective near-infrared reflectance spectroscopy (NIRS) predictive calibrations were developed for simultaneous multiple component measurement of constituents (protein, oil, and β-glucan contents) in whole and ground oat groats. The use of whole oat groats as a starting material represents an advancement in the science as it precludes the need for sample grinding. Samples were collected from the 2015 and 2016 crop years from various locations in the United States (South Dakota, North Dakota, Washington, Iowa, and Wisconsin), representing a large geographical region and diverse genetic range (N = 500). Predictive calibration equations were developed based on the modified partial least squares (MPLS) regression technique. Reference analyses were done using standard methods approved by AACC International and AOCS (AACCI Method 32-23.01 for β-glucan content, AACCI Method 46-30.01 for crude protein content, AOCS Standard Procedure Am 5-04 for oil content, and AACCI Method 44-15.02 for moisture content). The use of validation sample sets for each constituent, which were independent of samples used in NIRS calibration development, served as additional evidence of accuracy and precision. High coefficient of determination (R2) and one minus variance ratio (1-VR) and low standard error of calibration (SEC) and standard error of cross-validation (SECV) values provided evidence supporting the accuracy and precision of the calibration models developed for estimation of oat β-glucan, protein, and oil contents. The NIRS calibration for estimation of β-glucan content of ground oat groats yielded R2, SEC, SECV, and 1-VR values of 0.94, 0.16, 0.22, and 0.87, respectively. Protein calibration for ground oat groats yielded R2, 1-VR, SEC, and SECV values of 0.94, 0.93, 0.61, and 0.64, respectively. Calibration employing ground oat groats for oil content estimation yielded high R2 and 1-VR values of 0.93 and 0.92, respectively, and low SEC and SECV values of 0.23 and 0.26, respectively. Whole oat groat NIRS calibrations proved to be as effective as ground groat calibrations. Whole oat groat β-glucan calibrations yielded excellent R2, SEC, SECV, and 1-VR values of 0.93, 0.18, 0.23, and 0.89, respectively. For protein calibrations of whole oat groats, R2, SEC, SECV, and 1-VR values were 0.92, 0.70, 0.80, and 0.89, respectively. Oil content calibration developed with whole oat groats yielded R2, SEC, SECV, and 1-VR values of 0.90, 0.27, 0.30, and 0.88, respectively. This study showed that NIRS is an accurate and effective technology for oat quality measurement in plant breeding programs and food processing