DETERMINATION OF MOISTURE-CONTENT OF MUSHROOMS BY VIS NIR SPECTROSCOPY

Feasibility of the determination of the moisture content of intact individual mushrooms (Agaricus bisporus) by visible and near infrared reflectance spectroscopy (Vis-NIR) was studied. The convection drying method was found to be suitable to obtain reference values for the calibration equation. The standard error of the laboratory procedure ranged from 0.16 to 0.42%. Modified partial least square regression was used to develop the calibration equations. The importance of different segments of wavelength, the effect of light scattering and the use of data processing on the prediction of moisture content were evaluated. The equation obtained using the wavelength segment 600-2200 nm with first derivative and scatter correction had the best performance with a standard error of cross-validation of 0.64%. This equation performed very well when validated using a separate set of mushrooms of the same kind as those in calibration set. This equation, however, did not perform well when using mushrooms from a different treatment. Accuracy of prediction was re-established by adding typical spectra from the second group of mushrooms to the calibration set and performing recalibration.