The Physicochemical And Rheological Property Of Barley β- Glucan And Its Application In Cosmetics

Barley(Hordeum vulgare L.var. Nudum Hook.f) which contains abounding bioactive ingredient β-glucan is a feature crops in Tibetan Plateau. In recent years, barley has arised wide attention. In this paper, β-glucan was extracted from by means of hot water with barley as raw materials. Based on the single factor experiment, technological parameters of extraction has been defined. The β-glucan was purification by active carbon asorbtion and Sephadex G-200 column chromatography. Then the physio chemical and rheological properties of β-glucan was characterized. The application of β-glucan in cosmetic was also researched. The results showed as follows:(1) The best extraction condition of β-glucan:liquid ratio was 1:20,extraction temperature was 50℃,extraction time was 3h, ethanol volume was 3v,ethanol concentration was 80%, ethanol precipitation time was 4h,the yield was 4%-5%.The β-glucan was mainly existed in aleurone layer. The β-glucan was purified by active carbon asorbtion and Sephadex G-200 column chromatography,the purity was nearly 85% and the protein content was below 4%.(2) The physicochemical properties of β-glucans from barley flour and bran was compared.The barley β-glucan has higher molecular weight.XRD and thermodynamics tests indicated the β-glucans from barley flour and bran were all noncrystalline but thermostable polymers. DSC plots obviously showed that the β-glucan from barley bran had higher onset temperature and peak temperature,which could attributed to lower lower DP3:DP4 ratio in β-glucan chains. In SEM observation, the barley bran β-glucans showed more tight surface,which may be caused by its higher molecular weight.(3) In the steady shear experiment, the β-glucan solution exhibited newtonian fluid behavior at low concentration and showed pseudoplastic fluid behavior at high contration. This indicated that at the high shear region, the destruction rate for entanglement of β-glucan molecular chains was higher than formation rate, resulting in decrease of viscosity.In the frequency sweep test, the β-glucan solution exhibited liquid liked behavior and showed solid properties at high concentration. For the moderate concentration of β-glucan showed frequency dependence,which would caused the interaction between β-glucan chains and formed network(gel). G’max increased with concentration of β-glucan which indicated the increase in number of cross-links in network. Two-stage drop of G was showed in temperature sweep,the first stage drop was caused by molecular chain loosening,the second stage drop wascaused by change in molecular structure and configuration.The β-glucan solution exhibited thixotropic in the experiment condition.The β-glucan solution violate Cox-Merz rules indicated a tenuous network which remains intact under low-amplitude oscillation but is disrupted by continuous shear(4) The β-glucan was applied in cream and astringent system and skin water content was measured, barley β-glucan can significantly improved moisturizing ability of cosmetic system.