Kinetics of dehydration of green alfalfa

Artificial drying is an important step in processing of green crops in order to preserve their freshness and nutrients for longer time at relatively lower costs. Forage crops, tea and tobacco are the major green crops where the commercial drying is a major operation in their processing. Fresh green alfalfa at about 75 to 80% moisture is subjected to drying in different types of dryers. In the case of alfalfa, the raw material consists of leaves, stems, chops and fine stems, each varying distinctly in their physical and structural characteristics. The moisture content is reduced from initial level to about 10%. The drying air temperatures range from 40 to 800 degrees C; the lower temperatures are used in conveyor dryers whereas high temperatures are used in rotary drum dryers. The results on drying behavior, and changes in physico-chemical properties during drying for components of green alfalfa over the temperature range of 40 to 800 degrees C are presented in this paper. The optimum temperature for drying from the stand point of color and protein solubility was found to be 175 degrees C.