Use of near infrared hyperspectral imaging to identify water matrix co-ordinates in mushrooms (Agaricus bisporus) subjected to mechanical vibration

In this study, white mushrooms (Agaricus bisporus) were subjected to physical perturbation by mechanical vibration. Hyperspectral, images were obtained after perturbation using a pushbroom line-scanning instrument operating in the wavelength range of 1000-1700 nm (7 nm spectral resolution). Changes in sample spectra arising from perturbation were examined by observation of difference spectra and partial least squares regression (PLSR) coefficients. Different spectral pre-treatments [multiplicative scatter correction (MSC), extended multiplicative scatter correction (EMSC) and standard normal variate (SNV)] were employed in order to decrease spectral variability caused by scattering and differences in the optical path length due to physical changes in the mushrooms induced by the perturbation. Candidate water matrix co-ordinates were proposed at 950 nm, 1174 nm, 1398 nm, 1433 nm, 1454 nm, 1496 nm and 1510 nm. Mechanical vibration increased the concentration of weakly hydrogen-bonded water and decreased that of strongly hydrogen-bonded water in the mushrooms without causing changes in the bulk moisture content.