Abstract:

The response surface methodology was used to optimize the drying conditions for shiitake mushroom using
infrared radiation. Using Box-Behnken design, a quadratic regression model was established indicating the effects of drying
temperature, slice thickness and radiation distance at 3 levels each on color L value, rehydration ratio, hardness, amino acids
and total sugar contents. Results showed that drying temperature was the major factor affecting the quality of dried shiitake
mushroom, followed by slice thickness. Color L, rehydration ratio, hardness, amino acids and total sugar content of shiitake
mushroom decreased with increasing temperature. A decrease in color L, rehydration ratio, and total sugar content was
observed with increasing slice thickness, yet amino acid content initially increased and then declined. The optimum drying
conditions were determined as follows: drying temperature, 55 ℃; slice thickness, 4.5 mm; and radiation distance, 120 mm.
Under these conditions, color L, rehydration ratio, amino acid content and total sugar content were measured to be 58.56, 5.32,
495.63 g, 818.12 mg/100 g and 281.37 mg/g, respectively, which were in close agreement with the values predicted by the
developed model.

Key words: shiitake mushroom, infrared drying, response surface methodology, amino acids, total sugar