| Tremella is a kind of medicine-food fungus which is very very nutritious. Due to such property, tremellas has been applied in the food industry as a thickener in order to take full advantage of its nutrients. In recent years, some studies on the rheological properties of the solution of tremella polysaccharides, were helpful for the application of tremella as a thickener. The objectives of this study were to investigatehe rheological properties of tremella powder solution, and the impact of tremella powder in mixed gun (Xanthan gum:Carrageenan-2:8) solution system on the gel performance. Futhermore,, the process technology of lotus seed beverage using tremella powder as a thickner was designed and optimized. Also, the quality and storage stability of such lotus seed beverage were examind.1. Rheological properties of tremella powder solution. This chapter mainly investgated the effect of the concentration, temperature, ionic strength(Na+、Ca2+)、 freezing, refrigeration,andpH on the rheological properties and the fluid type of the solution. Also, the impact of cooking process at high temperature and high pressure, and the light conditions on the stability of tremella powder were examined. The results showed that the viscosity decreased along with the increase of shear rate, representing non-Newtonian fluid. And the increasing temperature resulted inthe decrease of the viscosity. The results conformed the Arrhenius equation and the formula was obtained:y= 107.35x-2.6142, which could further obtain the activation energy(Eo=10.72KJ/mol) of 0.6%(w/w) tremella powder solution. Ionic strength(Na+、Ca2+)could reduce the viscosity of the solution, and Ca2+ showed more obvious effect than Na+. Freezing(-18℃) could significantly reduce the viscosity of the system, while refrigeration(4℃) hadless influence., The viscosity increased first and then decreased as the pH increased and the system had higher viscosity and stability at pH between 6 and 8. The viscosity of solution system was reduced when cooking at high temperature and high pressure. There was no obvious impact of light conditions on the viscosity of the system.2. The effect of tremella powder on the gel performance of the mixed gum system. This chapter mainly studied the changes of gel strength, texture properties (hardness, elasticity and cohesiveness), gel initiation temperature, melting temperature, dynamic viscoelasticity and the thixotropy when tremella powder was adding into the mixed gum. The results showed that hardness of the system decreased when the tremella powder was used. And the appearing thixotropic ring in this system had similar area as the system without the ingredient of tremella flour. Moreover, the tremella flour had no significant effect on the gel strength, elasticity, cohesiveness, initial temperature and melting temperature.3.The process technology and storage stability of Tremella lotus seed beverage. Based on the preliminary experiments about making Tremella lotus beverage, the optimum formula was further determined by orthogonal experiment. And the formula was as following:The amount of dry lotus seeds, tremella flour and mixed gum (Xanthan gum:Carrageenan=2:8) were 4%,0.4%and 0.3%, respectively. And the pH of the beverage was 5.5. Results of the storage stability tests showed that the browning index of the beverage did not change significantly, the emulsification also had good stability and the total bacterial count met the national standard GB4789.2-2010 within 180d, when stored at low temperature (4℃); When stored at room temperature(25 ℃), the browning extent deepened, the emulsification stability was reduced, and the total bacterial count increased. But the storage stability was even worse when samples stored at 37℃. |
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