InSb Focal Plane Array Chemical Imaging Enables Assessment of Unit Process Efficiency for Milling Operation

Abstract

In the dry milling of wheat flour, each unit process (roller mill, purifier, sifter, etc.) produces a mixture with varying amounts of wheat endosperm and non-endosperm byproducts. Chemical images with 82 000 pixels of each intermediate product stream issuing from an individual processing machine are readily analyzed in terms of the relative amount of endosperm and non-endosperm. Approximately three minutes is required to produce an image of each intermediate product stream. Applying partial least squares (PLS) chemometric software to identify individual pixels, which enables calculation of the relative amount of endosperm and non-endosperm, is not a time-limiting factor. When relative flow rates are known for each stream, mass balance can be calculated from each intermediate stream in terms of the product (endosperm content) and the lower value non-endosperm byproduct. Data is presented from a purifier in a commercial flour mill. Intermediate streams collected from a run with optimized operational parameters were compared to those of another run before adjustment. The endosperm (product) mass balance profile for each run enabled assessment of operational efficiency. The devised chemical imaging analysis system would be particularly useful in commissioning of a new mill or to optimize existing wheat milling systems. Also, when raw material differs from that for which previous optimization was established, a new optimization may be in order. The ability to acquire a large number of spectra from a specimen and apply multivariate statistics to identify each pixel and subsequently count pixels accommodates heterogeneity and reports the results from averaging a very large number of individual spectra. A second illustration of the utility of the imaging method is presented centering on streams from the first and second break unit operations at the beginning of the roller mill process.

Potential of a flatbed scanner for evaluation of flour samples for dark specks and flour color

“…Hyperspectral systems have also been studied for evaluating flour streams. Wetzel et al (2010) evaluated various flour streams from a flour purifier using hyperspectral imaging of flour samples that were loaded onto microslides. Wetzel's imaging methods provided data that were used to improve milling equipment operation and to adjust equipment to optimal performance levels, which produced higher amounts of the desired mill fraction.…”

Profiling Endosperm Purity of Commercial Mill Streams Preceded by Debranning Using Quantitative Chemical Imaging

“…Data for each sample were collected in triplicate. The operation of this instrument with respect to individual intermediate and flour mill streams has been described previously (1,12). The near infrared imaging spectrometer, which is equipped with four quartz tungsten halogen source lamps, employs a rectangular thermoelectrically cooled array of indium antimonide detector elements.…”

“…The ideal debranning operation in hard wheat milling would evenly remove the outer layers of the pericarp without removing any endosperm or breaking kernels. Potential benefits include the removal of harmful elements from the kernel surface, flour streams with higher "brightness, " and increased flour extraction and mill capacity (3).Direct endosperm purity assessment of individual mill streams using a chemical imaging technique has been described previously (1,11,12). Previous studies were restricted to individual unit processes, such as an individual purifier, laboratory table-top milling study of the break system, or ranking flour stream purity for an experimental pilot mill.…”

“…Direct endosperm purity assessment of individual mill streams using a chemical imaging technique has been described previously (1,11,12). Previous studies were restricted to individual unit processes, such as an individual purifier, laboratory table-top milling study of the break system, or ranking flour stream purity for an experimental pilot mill.…”

Progress in Quantitative Chemical Imaging of Refined Natural Products and Synthetic Mixtures

“…A significant increase in product yield from 67.7% to 73% endosperm was revealed experimentally from a commercial purifier before and after optimisation. 9 This was achieved when the effect of gravity was perturbed to some extent by the application of turbulent air flow within the purifier system. We were privileged to be able to use simultaneous collection of spectra from an 81,920 rectangular array of highly sensitive InSb solid state photodiodes.…”