| Grain ?-glucan is a non-starch polysaccharide presenting in the cell wall of grain.Grain ?-glucan has attracted more and more interests because it has physiological functions such as hypolipidemic,hypoglycemic and enhanced immune.In this study,?-glucan was extracted from oats and barley.The ?-glucan gel was also prepared and its properties and sustained-release properties were studied.The purity of the extracted oat ?-glucan(OG)and barley ?-glucan(BG)were 84.41%and 80.17%,respectively.The polysaccharide samples with different molecular weights were obtained after partial acid hydrolyzing,namely OGO,OG30,OG60,OG90 and BGO,BG30,BG60,BG90 with the weight-average molecular weight 136,123,68,51,439,268,132,and 67 kDa.The ratio of ?-(1?4)bond and?-(1?3)bond in oat and barley ?-glucan were 2.63 and 2.53,respectively,using gas chromatography-mass spectrometry.The ?-glucan gel was prepared in freeze-thawing method.The formation of freeze-thawed gel was studied by low-field nuclear magnetic resonance(NMR).Three relaxing components with different transverse relaxation time(T21,T22 and T23)were founded in the ?-glucan system.With the increase of the number of freezing and thawing,the T22 of barley ?-glucan increased rapidly after 5th freezing and thawing and A22 increased significantly after 3th freezing and thawing.Other concentrations and the different molecular weight ?-glucan showed different trend.The relaxation time T21,T22 and T23 rose first and then did not change.A21 and A22 first increased and then changed little while A23 first declined and then changed little.By performing the principal component analysis on the relaxation distribution curve,?-glucan gel of different concentrations and different molecular could be distinguished well.The rheological study showed that ?-glucan gel with higher mass fraction and smaller molecular weights has a larger elastic viscous modulus.This indicated that it formed more more physical ross-linked structure in gel.The results of scanning electron microscopy showed that ?-glucan solut ion with higher mass fraction and smaller molecular weight formed structure compact gel while ?-glucan solution with lower mass fraction and larger molecular weight formed structure loose gel.The binding of curcumin and dextran was explored by UV absorption spectroscopy,infrared spectroscopy,X-ray diffraction,and atomic force microscopy.The results showed that the reaction between curcumin and ?-glucan was mainly physical adsorption.Tetra-glucan freeze-thaw gel was also used as a carrier to release curcumin.The results showed:5%?-glucan solution by adding 1%?-glucan quality curcumin,repeated freezing and thawing 8 times,freeze-dried gel has the ideal sustained release.The release mechanism of curcumin in beta-glucan gel can be described by the Peppas equation.The release of curcumin in the oat ?-glucan gel is mainly the Fick diffusion mechanism,coated barley ?-glucan is a non-Fick spread. |
PDF Full Text Request