Italian-style egg pasta analysis

Italians can be quite fussy about their pasta. If the label says egg pasta, they expect the pasta to contain a high concentration of eggs, especially as egg pasta has a different flavour and taste to normal pasta and also tends to be more expensive. So it should come as no surprise that Italian chemists have now turned to NIR spectroscopy to help confirm that egg pasta is exactly what it claims to be.

The big problem with using NIR spectroscopy for this purpose, though, is that the egg pasta manufacturing process involves a drying step, which tends to have a major effect on the pasta’s composition and texture. This can make it difficult to pick out the specific influence of egg concentration on the NIR signal.

To investigate the effect this drying step has on the composition of egg pasta, Federico Marini and his colleagues at the University of Rome analysed 54 samples of egg pasta with NIR spectroscopy. These samples contained six different concentrations of egg, from 20% to 33%, and were dried at three different temperatures (40⁰C, 52⁰C and 65⁰C) and for three different lengths of time (4, 6 and 8 hours).

Analysing the resultant NIR spectra with a statistical technique known as ANOVA-Simultaneous Component Analysis revealed that the drying temperature was the single greatest influence on variations in the chemical composition of the egg pasta, followed by the drying time, with egg concentration bringing up the rear. This lack of influence doesn’t mean that the egg concentration can’t be determined from the NIR spectra, just that the influence of the drying temperature and time need to be taken into account first.

To do this, Marini and his colleagues employed another statistical technique known as locally weighted partial least squares regression. As they report in Food Chemistry, this produced a model that could indeed accurately determine the egg concentration of egg pasta from NIR data.

Indeed, this model was so accurate that Marini concludes that it could be used in the regular quality control of pasta samples, ensuring that lovers of egg pasta can now eat with confidence.

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