Abstract:
Taking old asparagus stems as test materials, the effects of different microwave predrying times on the drying quality of old asparagus stems were studied by microwave predrying method, in order to provide reference for the selection of microwave predrying time parameters in microwave hot air combined drying of old asparagus stems.The results showed that the DPPH free radical scavenging ability of the old asparagus stem powder treated by microwave for 2 minutes was relatively strong; the content of crude polysaccharide and oil holding capacity of the powder of microwave for 4 minutes were the best, which were increased by 6.30% and 96.43% respectively compared with single hot air; microwave for 6 minutes, the color retention of the powder was relatively best; the drying rate of microwave 8 minutes was the fastest, the average particle size of the powder was the smallest, and the specific surface area, water holding capacity and expansion force were the best, which were 129.00%,28.00% and 43.75% higher than single hot air.The powder treated by microwave for 2 minutes and microwave for 4 minutes was suitable to be added to various foods such as solid beverages as functional ingredients; the powder treated by microwave for 6 minutes was suitable for the production of functional ingredients with high requirements for product color; after microwave treatment for 8 minutes and microwave for 10 minutes.The powder was suitable for large-scale ingredient production, and was widely used in the processing of capsules, tablet candies and other series of large health food.