Investigation of moisture content uniformity of microwave-vacuum dried mushroom (Agaricus bisporus) by NIR hyperspectral imaging

Abstract

This study aimed to investigate the impact of microwave-vacuum drying (MVD) on moisture uniformity in mushroom slices and whole mushrooms (Agaricus bisporus) by near infrared (NIR) hyperspectral imaging in combination with multivariate analysis. The partial least squares regression (PLSR) models based on standard normal variate (SNV) preprocessing spectra obtained good results for predicting moisture contents (MC) with the coefficient of determination in prediction (Rp2) of 0.985 for mushroom slices and 0.963 for whole mushrooms. The MC of caps was 5–11 g/100 g higher than that of stipes for the first 12 min of drying and after 18 min of drying the MC of stipes was 6–22 g/100 g higher than that of caps. The MC of peripheral caps of whole mushrooms was 2–12 g/100 g higher than that of centers for the first 30 min of drying, but the MC of peripheral caps was 4–5 g/100 g lower than that of centers in the last 20 min of drying. In addition, the difference of MC between caps and stipes (6–22 g/100 g) in mushroom slices was more significant than that between the center and periphery (4–5 g/100 g) in whole mushrooms during the middle and later periods of drying procedure.