Drying characteristics and processing optimization of combined microwave drying and hot air drying of Termitomyces albuminosus mushroom

Abstract

Termitomyces albuminosus (termite mushroom) is an edible fungus growing from termitaries in certain parts of China. Recently, the mushroom has gained in popularity, but due to rapid post-harvest quality decay, novel processing techniques including drying are required. This study aimed to optimize the conditions of combined microwave and hot air drying for T. albuminosus. Factors including microwave density, air temperature, and moisture content at conversion point were investigated and optimized using the drying rate, protein content, color L*, DPPH scavenging ability, rehydration ratio (RR), texture, sensory, and overall score as responses. The results showed that the overall score dried at 1.83 W/g microwave density, 60°C hot air, and 50% moisture content at conversion point were 0.675, 0.575, 0.530, respectively. The optimum conditions of combined microwave and hot air drying were microwave density 2.0 W/g, moisture content 52% at conversion point, and hot air temperature 57 respectively. The optimum conditions of combined microwave and hot air drying L* was 54.16, DPPH clearance was 91.87%, RR was 2.41, pileus chewiness was 1,587.19 g, stipe chewiness was 4,457.28 g, sensory score was 7.3, and overall score was 0.793, while the sensory quality was very high. Therefore, microwave drying followed by hot air drying is an effective, suitable method to obtain dried T. albuminosus. Practical applications Termitomyces albuminosus is also known as Termitomyces and has a similar internal fiber structure, color, and flavor as chicken. Drying is one of the most important methods for edible fungi processing and the major aim is to decrease water activity, which in turn minimizes the chemical and physical modifications during storage. The conditions of combined microwave and hot air drying for T. albuminosus were investigated and optimized using the drying rate, protein content, color L*, DPPH scavenging ability, rehydration ratio, texture, sensory, and overall score as responses. The obtained process parameters were helpful, effective, and suitable for the application of combined microwave and hot air drying technology to preserve good quality, especially for T. albuminosus.