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Abstract Supercritical carbon dioxide extraction was used to remove the lignin from the bark. The extraction process was optimized by orthogonal test of 4 factors and 3 levels. The component analysis was carried out by gas chromatography-mass spectrometry(GC-MS).The results showed that the sequence of factors affecting lignin removal from bark was temperature>pressure>entrainer volume>time. The lignin removal rate was 71.62% when the extraction temperature was 160 ℃, the extraction pressure was 20 MPa, the extraction time was 90 min and the entrainer was 2.0 mL.The results of GC-MS analysis showed that aldehydes, alcohols and ketones containing ethoxyl and pentacyclic structure existed in all extracts, which indicated that not only lignin but also cellulose and hemicellulose carbohydrates were degraded during the extraction process. Scanning electron microscopy was used to compare the skin texture before and after supercritical extraction. The results showed that after supercritical extraction, many holes appeared on the surface of the sample, and the smooth surface became rough and uneven.
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Received: 18 September 2020
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2020, Vol. 33 
