DETERMINING PECKY RICE KERNELS USING VISIBLE AND NEAR-INFRARED SPECTROSCOPY

Figures & data

Table 1. Summary of Calibration and Validation Results Using PLS Models for Classifying Pecky and Sound Rice Kernels^a

		Calibration (%)			Validation Results (%)
Spectra Region/Sample Sets	F^b	Sound Rice	Pecky Rice	Average	Sound Rice	Pecky Rice	Average
		500–750 nm
Peck face up^c	6	100	100	100	100	100	100
Peck face down^d	6	100	99.0	99.5	100	98.0	99.0
Peck face down^d	6	100	99.0	99.5	100	98.0	99.0
Both^e	6	100	99.3	99.7	100	99.3	99.7
500–1700 nm
Peck face up	8	100	100	100	100	100	100
Peck face down	8	100	99.7	99.8	100	99.3	99.7
Both	8	100	99.7	99.8	100	99.3	99.7
750–1700 nm
Peck face up	8	100	100	100	100	100	100
Peck face down	8	100	100	100	100	100	100
Both	8	100	100	100	100	100	100

^aFor both calibration and validation sample sets, sound rice kernels=300; pecky rice kernels=300 including 100 kernels with large peck area, 100 kernels with peck on center of the kernel, and 100 kernels with peck on tail of the kernel.

^bF=number of PLS factors.

^cPeck up = a peck area faces the illumination light.

^dPeck down = an undamaged area faces the illumination light.

^eBoth=50% of peck up +50% of peck down.

Table 2. The Color Variations Between Pecky and Sound Rice Kernels Measured as L, a, and b Values in the L*a*b Color Space

	L		a		b
Class	Avg.	SD	Avg.	SD	Avg.	SD
Sound rice	40.76	2.66	3.85	0.36	4.75	0.39
Pecky rice	39.24	5.36	6.27	1.69	7.42	1.76

Figure 1. Absorption curves for pecky and sound rice kernels. Vertical bar represents one standard deviation.

Figure 2. Beta coefficient curve of PLS model (6 PLS factors) for classification of pecky and sound rice kernels.

Table 3. Summary of Calibration and Validation Results Using the Linear Discriminant Functions for Classifying Pecky Rice and Sound Rice Kernels^a

	Calibration Accuracy (%)			Validation Accuracy (%)
Wavelength (nm)	Sound Rice	Pecky Rice	Average	Sound Rice	Pecky Rice	Average
480 and 590	100	98.7	99.3	99.7	99.0	99.3
480 and 1095	100	94.0	97.0	98.7	90.0	94.3
875 and 985	99.7	84.3	92.0	99.7	80.6	90.2

^aFor two-wavelength models, 600 kernels were used for calibration and validation sample sets, respectively. The pecky-rice kernels contain 50% of kernels with peck up and 50% of kernels with peck down.

Figure 3. Coefficient of determination (r ²) as a function of single and two wavelengths for single and two-wavelength models.