Dehydration of concentrated ganoderma lucidum extract by microwave-vacuum drying

The concentrated Canoderma lucidum extract is very stick and heat-sensitive,and it is very different to be dried.Combination of microwave-vacuum drying and conventional vacuum drying was investigated as a potential method for drying concentrated Ganoderma Lucidum extract.The moisture of concentrated sample was about 70% (wet basis).It was dried by microwave-vacuum until the moisture content reached 10% (wet basis),and then by conventional vacuum drying at the temperature of 50℃ to final moisture content less than 5% (wet basis).The retention of polysaccharide and tritepenes of Ganoderma Lucidum dried by this method were evaluated and compared with those dried by freeze drying and conventional vacuum drying.The comparison showed that the quality of Ganoderma Lucidum dried by the current method was close to that of freeze dried Ganoderma Lucidum and much better than that of conventional vacuum dried ones.