Prediction of Corn Dry-Milling Quality by Near-Infrared Spectroscopy' (1996)

Cereal Chem. 73(5):543-546 The potential for near-infrared (NIR) reflectance spectroscopy to predict corn dry-milling quality has been investigated. NIR spectra were obtained from samples of whole-kernel yellow dent corn. Dry-milling quality of the samples was evaluated with a Tangential Abrasive Dehulling Device (TADD), and by a short-flow laboratory milling procedure that allowed calculation of a milling evaluation factor (MEF). Calibrations relating TADD index and MEF to NIR measurements were developed and tested with validation sample sets. The results indicate that NIR spectroscopy can predict dry-milling characteristics with a reliability suitable for at least rough screening. For MEF, the best calibration yielded a correlation coefficient of 0.90 and a standard error of prediction (SEP) of 1.55%. SEP values for TADD index were somewhat higher. Derivatization of the NIR spectra lowered the SEP values compared to the use of underivatized log IhR measurements. The availability of a rapid test for predicting the dry-milling characteristics of corn would be highly useful in a breeding program for selecting cultivars with good milling qualities, and for identifying corn shipments in commerce that have good industrial processing characteristics. Several researchers have investigated the relationships of various chemical and physical tests to drymilling yields. In general, to produce a high yield of the desired No. 4 flaking grits, corn with a high ratio of vitreous to floury endosperm is needed. Paulsen and Hill (1985) found that corn with a high test weight and low breakage susceptibility provided the best yield of flaking grits from a commercial dry mill. In addition to test weight, other measures of density including 100 kernel weight and % floaters, as determined in a solution with specific gravity of 1.275, were also highly correlated with the yield of grits. Kirleis and Stroshine (1990) reported that milling evaluation factor (MEF) values, determined with a short flow laboratory milling procedure, were highly correlated (r = 0.92) with flaking grits yield obtained on a commercial corn dry mill. Kirleis and Stroshine (1990) then determined the milling quality of three dent hybrids exposed to different drying conditions using MEF values, and they also measured various physical properties of the samples. For the samples evaluated, a two-variable regression model combining test weight and kernel density was highly correlated with MEF values (R = 0.907). Similarly, for 15 different samples Wu and Bergquist (1991) found a significant correlation (r = 0.894) between kernel density measured with an air comparison pycnometer and total grits obtained by a laboratory milling procedure. In another study, Peplinski et al (1992) reported that first break grits yield was higher for corn with high test weight, low % floaters and a low percentage of broken kernels as measured by the Stein breakage test. Hill et al (1991) reported a study with a larger number of samples (98) in which several of the more complex physical and chemical tests had correlations >0.75 with the MEE The best predictors of MEF were Stenvert time to grind, % oil, % floaters, and % flint genetic background in the cultivar. In general, higher correlations between the physical tests and MEF were obtained for flint samples than for dent samples.