Effects of Drying Methods on Physical and Chemical Properties and Antioxidant Activity of Alfalfa Superfine Powders

In order to study the effect of different drying methods on the physical and chemical properties and antioxidant activity of alfalfa superfine powder,through orthogoral experiment,the optimal color protection method was determined and the parameters of hot air drying were optimized by using the total color difference of alfalfa as an index. Alfalfa superfine powder obtained by hot-air drying and vacuum freeze-drying were compared with the difference of physicochemical properties and antioxidant activity by determining the physical and chemical indexes of alfalfa including particle size,solubility,water holding capacity,oil holding capacity and DPPH free radical scavenging rate. The results showed that the optimum technological parameters of hot air drying were as follows:when the drying temperature was 70℃,the drying time was 8 h and the coloring agent was 0.15% L-cysteine,the prepared alfalfa powder had good physical and chemical properties. Moreover,the decreasing of the fine particle size of alfalfa could significantly improve the antioxidant activity of alfalfa meal. Alfalfa powder made by vacuum freeze drying had a good physical and chemical properties,and its nutritional value and antioxidant activity could be retentive well,while it had more time and energy consumption. In contrast,the physicochemical properties and antioxidant activity of alfalfa powder made by hot air drying was relatively poor and had a less time and energy consumption.