World Grain - October 2011 - 78

MILLINGOPERATIONS

ﬂected by the specimen to the lens (Figure 1). The lens focuses the rays onto a tunable ﬁlter from there to the focal plane array. Solid state detector elements in the array of the high tech instrument perform approximately 82,000 analyses simultaneously which represents the number of pixels in a ﬁeld of view on the sample stage. Chemical features distinguish the component of the spectrum from each of these pixels. Image contrast is produced through the choice of wavelength. Endosperm can be highlighted in an image using the 2100 nm wavelength strong absorption band of the spectrum. Similarly, nonendosperm can be highlighted with the 1740 nm wavelength image. A schematic of the process is provided in Figure 1. The commercial Malvern instrument used at KSU was originally developed by chemists at the National Institute of Health in Bethesda, Maryland, to examine diseased tissue in the health ﬁeld. In the pharmaceutical industry, the imaging near-infrared spectrometer is used on medication to assure proper dosage of multiple active ingredients in an excipient matrix — i.e. the aspirin, acetaminophen and caffeine in an APC tablet — would appear as different false color coded spots in the tablet image to show the distribution and content of each. Very pure endosperm, such as in the 1st Midds top ﬂour stream from the KSU Pilot Flour Mill in Shellenberger Hall, is used as the “standard” for comparison. The multiwavelength spectroscopic proﬁle spectra are obtained to proﬁle the endosperm. Bran obtained from the same milling that is relatively free of endosperm is ground, and the multiwavelength spectroscopic proﬁle spectra are obtained to highlight nonendosperm. These reference data enable statistical manipulation of the spectra of each pixel in the image to classify it according to the binary system. The false color image contrast shows the predominant composition of each pixel as shown in Figure 2. Conceptually, the binary code of 1 or 0 is applied, and then the count of endosperm pixels is divided by the total number of pixels in the image to obtain the endosperm concentration of the optical ﬁeld

of view. In practice, a multivariate statistical process shades each pixel, the summation of which produces the concentration of endosperm and non-endosperm. Validity of the endosperm numerical values are subject to the replication of ﬁelds of view. The perception provided by the false color images is numerically evaluated by further treatment of the data by dedicated software furnished with the instrument. The analytical reliability has been established by extensive experiments in the Microbeam Laboratory at KSU. Figure 2 shows images from a commercial mill puriﬁer before adjustments. The calculated endosperm mass balance is shown in red. The warm color or redness of the image indicates higher amounts of endosperm. Before adjustment, the product was 64% and the rework was 37%. After adjustment, the product yield increased to 77% with 23% rework, which is certainly a dramatic difference. The diagram in Figure 3 (page 80) depicts a conventional ﬁrst and second break laboratory ﬂow. The second cut which is normally directed to a Sizings system for processing was separated further with stocks from both ﬁrst and second break combined for endosperm content. The fractions imaged are designated A through J in descending particle size. Figure 3 shows typical false color images of intermediate products in which the warm color (red) shows the endosperm present in each image. Note that endosperm content is more prevalent in the ﬁner fractions based on the red false color in the image. Also note that the ﬁner material is more homogeneous. Endosperm values stated as percent and listed by sieve size are the means of the three replicate specimen images calculated independently. From three different ﬁelds of view the image chosen to show in the diagram is the one that best represents the calculated numerical mean. Three ﬁelds of view for a heterogeneous material produce numbers that vary. For the coarse heterogeneous material statically a number of ﬁelds of views must be averaged. By the third sieve level there is less heterogeneity. For the top three images tail over of the 1041, 900, 750

Fig. 2. Material quantity and quality balance before and after adjustment. (Courtesy of Wetzel, Posner, Dogan and Applied Spectroscopy)
Endosperm mass balance before adjustment IN 90.3% 796kg/h SOT FC FC 86.8% SC (no second clear) 64.6% product 37% rework FOT 97.9% 104kg/h 139kg/h SC FOT 80.1 % 62 kg/h UOT 58.8% 51 kg/h 89.6 % 1463kg/h SOT IN Endosperm mass balance after adjustment UOT 62.2 % 188 kg/h

99.2% 514kg/h

99.6% 988 kg/h 99.1% 134 kg/h 76.7% product 23% rework

84.8 % 105 kg/h

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World Grain - October 2011

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