2.2.4. Freeze drying
Two hundred grams of A. bisporus slices samples was first frozen
at −30 ± 2 °C, and FD was performed in a lab-scale freeze dryer
(FD-1A-50, Beijing Boyikang Laboratory Instruments Co., Ltd, China) at
−50 °C with a chamber pressure of 15 Pa until constant weight was
obtained with 4.28% ± 0.47% (w.b.) water content. One FD experiment
was performed for each treatment (NOB, HWB and MWB), and several
samples from each experiment were used for later tests.