Study On Rheological Properties Of Chitosan, Sodium Alginate, Fenugreek Gum And Thier Complex System

Natural polymer polysaccharides as food additives and drug carriers are used inthe food and pharmaceutical fields. Rheological properties play an important role infood texture, storage, transport and processing, while the sol-gel conversion processand the gel properties provide important technology support for preparation of drugcarrier. Rheological properties of chitosan, sodium alginate and fenugreek gum werefirstly studied in this paper, and then studied the rheological properties of Cs/GA,Cs/HP-?-CD, SA/HMP and FG/Na-CMC complex system. It aimed at providecorresponding technical support to complex sol/gel application in food and medicine.Rheology research contents were based on:1) measurement of steady-shear flowproperties to find a well rheology model;2) evaluation of the thixotropy anddynamical viscoelasticity properties at different concentrations; and3) comprehensiveanalysis of the rheological properties using multiwave-temperature ramp test underthe condition of temperature and frequency changed synchronously.4) Gel formation,gel strength and creep experiments were investigated by rheological methods.1. Rheological study of Cs and its complex system showed: Cs solutions(0.005-0.025g/mL) were all accorded with Cross model of rheology, and the higherthe concentration, the smaller the critical shear thinning rate. The loss modulus (G'')was always greater than the storage modulus (G')?and the difference between thevalue of G' and G'' approached gradually with the frequency increased. The fluid-likeviscoelastic behavior was found at the lower frequency and the network crosslinkedstructure was formed at the higher frequency. The complex viscosity reduced with theincrease of temperature and frequency. Cs/GA complex had a good anti-shearproperties, the thixotropic recovery rate of Cs/GA (TB4R3, TB5R4) complexes werefastest. Cs/GA complex exhibited poor oscillation stability (especially the frequencywas greater than1rad/s) and had a good temperature stability. The curves of viscosityof Cs/HP-?-CD complex system with shear rate curves accorded with the equation of=a+b+c. Hysteresis loop area of Cs/HP-?-CD increase at first and then decreased,2%Cs/15%HP-?-CD mixed sols had the strongest thixotropic properties.2. Rheological study of SA and its complex system showed: SA and SA/HMPsols were well correlated with the Cross model, more pronounced at the highestconcentration of SA. Their flow activation energy tended to decrease with theincrease of shear rates, which indicated that SA and SA/HMP sols were not sensitiveto temperature under shearing, and the larger the shear rates, the less sensitive totemperature. The measurement of the area of Hysteresis loops resulting fromupward-downward flow curves showed that the SA solutions exhibited strongthixotropic behavior, and the higher the SA concentration, the stronger the thixotropicbehavior. Oscillatory frequency sweep results showed that SA solutions exhibited thefuid-like viscoelastic behavior. SA/HMP (RSA?HMP=8:2,6:4,5:5) complex showed afuid-like viscoelastic behavior, which their storage modulus (G') were always greaterthan loss modulus (G'') but have no cross point, For SA/HMP (RSA?HMP=4:6,2:8)complex, their G' and G'' have a cross point, which showed the presence of sol-gelphase transition, with a solid-like viscoelastic behavior, SA/HMP (RSA: HMP=8:2)complex became a gel after a short time by adding glucose-?-lactone (GDL) and thegel have the maximum strength, the elastic recovery index ?J was found to be close to100%and the mixed gels are thermally irreversible.3. Rheological study of FG and its complex system showed: FG solutions andFG/Na-CMC complex systems exhibited pseudoplastic fluid characteristics, the flowcurves of FG consistented with power-law model when the concentration was lessthan0.4%(w/v). Structure of FG solutions with concertrations of0.5%,0.6%,0.7%and RFG: Na-CMC=5:5,4:6,2:8complex systems were destroyed in thixotropic test, butthe structure of other concentrations of FG solutions and RFG: Na-CMC=10:0,8:2,6:4complex systems were recovered in thixotropic test. In strain test, FG solutions andFG/Na-CMC (RFG: Na-CMC>5:5) complex systems exhibited that their tan ? values wereless than1, adding Na-CMC caused a decrease viscoelastic to the system. The tan ?values of FG solutions initially decreased with an increase of angular frequency.TheRFG: Na-CMC=4:6,2:8,0:10complex systems at a frequency range of1-10s-1exhibiteda behavior of pseudo-liquid behavior. In addition, the tan ? value increased with thetemperature increasing (tan ? <1). The systems showed a similar rheological behavior of liquid when RFG: Na-CMC=2:8,0:10. The system appeared a transformation fromliquid-like phase to solid-like when the temperature rises to a certain value, and thelarger the Na-CMC's concentration, the higher convert temperature.