Influence of drying methods on the physicochemical properties and nutritional composition of instant Tremella fuciformis

Instant Tremella fuciformis is ready to eat after adding hot water and is a delicious edible mushroom food. However, the drying method affects the quality of product. The present work evaluated the effects of freeze drying (FD), microwave drying (MD), and hot air drying (HAD) on shrinkage ratio, rehydration ratio, microstructure, polysaccharide and free amino acids of instant Tremella fuciformis. These three drying methods significantly changed the color and reduced the total amount of amino acids of dried products. FD sample possessed a three-dimensional network with porous, loose and large voids, so it had a slighter shrinkage and a better rehydration effect compared with the MD and HAD one. The polysaccharide content, uronic add content and soup's viscosity of FD products were significantly higher than MD and HAD. Therefore, FD was more suitable for obtaining high-quality instant Tremella fuciformis products than MD and HAD.