Study on the Changes of Cell Wall Polysaccharide and Their Degrading Enzyme Activities during the Development of Lycium barbarum Fruit

To further explore the metabolism of Lycium barbarum polysaccharides, the cell wall microstructure of Lycium barbarum fruits in different growth periods was observed by transmission electron microscopy, and the cell wall polysaccharide content and its degrading enzyme activity were extracted by chemical method. The changes of polysaccharide components in cell wall of Lycium barbarum fruits in different growth periods were analyzed by microcopolymer Raman spectroscopy. The correlation between the content of polysaccharide in cell wall and the activity of degrading enzyme was analyzed. The results showed that the changes of cell wall structure mainly occurred during 28~35 d, with the cell wall becoming significantly thinner, pectin degrading, and the cell wall structure gradually collapsing. Cell wall material (CWM) content increased first and then decreased, and water-soluble pectin (WSP) content increased significantly (P<0.05). Sodium carbonate-soluble pectin (SSP) and Hemicellulose contents increased firstly and then decreased. The activity of polygalacturonase (PG), β-galactosidase (β-Gal) and cellulase (Cx) increased, and the activity of pectin methylesterase (pectin methylesterase) increased. The activity of PME and β-hexosaminidase (β-Hex) decreased at first and then increased. The results of correlation analysis showed that the polysaccharide content of cell wall was significantly correlated with the activity of cell wall degrading enzyme during the growth and development of Lycium barbarum fruit (P<0.05). With the development and maturation of Lycium barbarum fruit, the microstructure of cell wall showed a trend of cell wall collapse and polysaccharide degradation with the change of degrading enzyme activity. The results have theoretical and practical significance to improve the processing quality of Lycium barbarum fruit and formulate suitable storage strategies.