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Near-Infrared Spectroscopy for Estimation of Ergosterol Content in Barley: A Comparison Between Reflectance and Transmittance Techniques

The fungal-specific lipid ergosterol correlates with fungal biomass and often also with the degree of mycotoxin contamination of cereals. We compared the ability of a near-infrared reflectance (NIR) instrument with a broad wavelength range (400–2500 nm) and a near-infrared transmittance (NIT) instrument with a narrower wavelength range (850–1050 nm) to predict the ergosterol content of naturally infected barley samples. The two instruments were equally good at predicting ergosterol content in Swedish samples (r² = 0.81 and 0.83 for NIT and NIR, respectively). The NIT instrument was then used for samples from three countries (Sweden, Ireland, UK). This model had about the same root mean-squared error (≈5 mg of ergosterol/kg, db, of grain) as the dataset with only Swedish samples, although the r² value was lower (0.58). The investigation has shown that it is possible to predict ergosterol content in whole barley samples using NIR or NIT instrumentation, and acceptable models can be obtained using different barley cultivars and samples from different countries and harvest years. This should make it possible to routinely predict the fungal biomass at grain terminals.