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Application of calibrations to hyperspectral images of food grains: example for wheat falling number

Caporaso, Nicola; Whitworth, Martin B.; Fisk, Ian D.

Authors

Nicola Caporaso

Martin B. Whitworth

Ian D. Fisk ian.fisk@nottingham.ac.uk



Abstract

The presence of a few kernels with sprouting problems in a batch of wheat can result in enzymatic activity sufficient to compromise flour functionality and bread quality. This is commonly assessed using the Hagberg Falling Number (HFN) method, which is a batch analysis. Hyperspectral imaging (HSI) can provide analysis at the single grain level with potential for improved performance. The present paper deals with the development and application of calibrations obtained using an HSI system working in the near infrared (NIR) region (~900–2500 nm) and reference measurements of HFN. A partial least squares regression calibration has been built using 425 wheat samples with a HFN range of 62–318 s, including field and laboratory pre-germinated samples placed under wet conditions. Two different approaches were tested to apply calibrations: i) application of the calibration to each pixel, followed by calculation of the average of the resulting values for each object (kernel); ii) calculation of the average spectrum for each object, followed by application of the calibration to the mean spectrum. The calibration performance achieved for HFN (R2 = 0.6; RMSEC ~ 50 s; RMSEP ~ 63 s) compares favourably with other studies using NIR spectroscopy. Linear spectral pre-treatments lead to similar results when applying the two methods, while non-linear treatments such as standard normal variant showed obvious differences between these approaches. A classification model based on linear discriminant analysis (LDA) was also applied to segregate wheat kernels into low (250 s) HFN groups. LDA correctly classified 86.4% of the samples, with a classification accuracy of 97.9% when using HFN threshold of 150 s. These results are promising in terms of wheat quality assessment using a rapid and non-destructive technique which is able to analyse wheat properties on a single-kernel basis, and to classify samples as acceptable or unacceptable for flour production.

Journal Article Type Article
Publication Date Apr 28, 2017
Journal Journal of Spectral Imaging
Electronic ISSN 2040-4565
Publisher IM Publications
Peer Reviewed Peer Reviewed
Volume 6
Issue a4
APA6 Citation Caporaso, N., Whitworth, M. B., & Fisk, I. D. (2017). Application of calibrations to hyperspectral images of food grains: example for wheat falling number. Journal of Spectral Imaging, 6(a4), doi:10.1255/jsi.2017.a4
DOI https://doi.org/10.1255/jsi.2017.a4
Keywords Hyperspectral imaging, Partial least squares calibration, Food grains, Whole wheat kernels, Hagberg Falling Number (HFN)
Publisher URL https://www.impublications.com/mjsi/jsi-abstract.php?code=I06_a4
Copyright Statement Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by/4.0

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Copyright Statement
Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by/4.0





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