Durum Wheat
Durum wheat (Triticum turgidum subsp. durum) is the second most cultivated species of wheat after common wheat, although it represents only 5% to 8% of global wheat production. Durum in Latin means 'hard', and this species is the hardest of all wheats. This makes it ideal for pasta production, by ensuring that the shape of the pasta is retained after cooking.
Data Collection
For this experiment, we purchased Caputo Semola Rimacinata durum wheat flour, and Woolworths Plain flour. From this we filled 23 small plastic bags of flour, each weighing 50 gm, with different ratios of durum and plain flour.
Each of these 23 sample bags was scanned three or four times with one of our NIR spectrometers, resulting in a set of 79 NIR spectra.
We also purchased flour from two other Italian Semola Rimacinata brands, a New Zealand durum wheat flour (from a non-amber variety), and samples of 'High Grade' bread flour, spelt flour, and Italian 'doppio zero' soft flour from several brands. Their NIR absorbance are shown here. With such an obvious difference between the spectra for the semola rimacinata brands, and the 'bread' wheat flours obtained from local supermarkets, we should be able to build a reasonably accurate model to predict mixtures of the two types of flour.
Model Building Results
We took the 79 spectra and built a model to predict the % durum flour in mixtures of amber durum and plain wheat flour. Since often of these spectra were taken from the same sample bag, we used group-wise cross validation to generate the following plot, to indicate how well our model will perform. Each red dot is a prediction made for one of the 79 spectra.
Italian law allows semola rimacinata flour to contain up to 3% non-durum wheat. Therefore any practical application of NIR to detect possible adulteration of durum wheat flour should probably focus on small amounts of adulteration, up to about 10%. For this reason, its of interest to examine the accuracy of our model in the 80% to 100% range.
What Is Cross Validation?
(to be completed)
References
Marina Cocchi, Caterina Durante, Giorgia Foca, Andrea Marchetti, Lorenzo Tassi, Alessandro Ulrici,
Durum wheat adulteration detection by NIR spectroscopy multivariate calibration,
Talanta, Volume 68, Issue 5, 2006, Pages 1505-1511, ISSN 0039-9140
De Girolamo, A.; Cervellieri, S.; Mancini, E.; Pascale, M.; Logrieco, A.F.; Lippolis, V.
Rapid Authentication of 100% Italian Durum Wheat Pasta by FT-NIR Spectroscopy Combined with Chemometric Tools.
Foods 2020, 9, 1551. https://doi.org/10.3390/foods9111551
