Effects of different pretreatments on dynamic countercurrent extraction of polysaccharides from Ganoderma

Abstract

Microwave radiation under vacuum (VM), extrusion and a combination of both were studied as potential pretreatment methods prior to dynamic countercurrent extraction of polysaccharides from Ganoderma. The effects of four pretreatments: soak (SO), soak + microwave radiation under vacuum (SVM), soak + extrusion (SE) and soak + microwave radiation under vacuum + extrusion (SVME) on disruption of cellular wall and on the yield of polysaccharide extraction were investigated and compared. The stickiness and turbidity of the extracts were also considered to evaluate the impacts of different pretreatments. The results showed that the SVME ruptures the samples cellular wall and membranes the most and gives the highest yield of polysaccharides at 1.928%, while the other pretreatment methods lead to lower values. SVME polysaccharides yield was 23% higher than that of SO. However, the conventional step by step extraction with the same fresh extractant only reached the yield of 1.902%. Combining SVME with dynamic countercurrent extraction consumed much less extractant and an extraction yield of 1.928% was achieved if the dynamic countercurrent extraction (DCCE) was conducted in continuous mode. On the other hand, the current method consumed less microwave energy due to just a few minutes of effective microwave irradiation.