Study On The Rheological And Gel Properties Of Carrageenan And Algin

Carrageenan and algin are two kinds of polysaccharides which are extracted from the seaweed, and they had broad applications in food. The object of this thesis is to study the rheological and gel properties of algin and carrageenan. The main results are as follows:1) Study on the rheological properties of the aqueous solution of carrageenan and algin:The results showed that carrageenan and algin were both pseudoplastic fluid and their flow curve had a good correlation with the power law model. In the low-frequency region, they mainly exhibited viscous, while in the high frequency region mainly flexibility. When the concentration was 2.0%, they both had thixotropy, and the lower the concentration was, the smaller the thixotropic central was.2) Study on the gelling properties of carrageenan and algin.Carrageenan was a hot reversible gel, and it had the thermal hysteresis significantly in the process of heating and cooling.The maximum gel strength was found when the gelling time was 8h .The KCl concentration had great effect on gel strength, with the KCl concentration increasing, the gel strength firstly increased and then reduced, the maximum gel strength was found when the content of KCl was 0.8%.Alginate gel was a non-reversible gel.In the system of CaCl2,the content of CaCl2,temperature of CaCl2 and the composition of mannuronic acid / guluronic acid ( M/G) had made difference on the properties of alginate calcium gel .The texisle strength and absorbency ability of gel was the best when the content of CaCl2 and the temperature of CaCl2 was 2.0% and 50℃respectively; The texisle strength of alginate calcium by high G algin was better than that of by high M, while the absorbency ability of water by high G was smaller than that of high M. The IR spectra results showed that the loacation of -OH peak migrated to the high wavenumber and C-H stretching weak, when alginate sodium changed into alginate calcium.In GDL system, the gel structure was more uniform, but the concentration of Ca2+ and GDL and the M / G ratio had great effect on the gel properties. The storage modulus, loss modulus, complex viscosity, gel strength gradually increased with the increasing of calcium concentration, while the gel time gradually decreased. As the M / G ratio increased, the storage modulus, loss modulus and gel strength diminished, while tanδand gel time gradually increased.3) Study on the synergy of algin, carrageenan and other gel.Synergy was between carrageenan and konjac gum, and the mixture was a kind of heat reversible gel, the melt temperature was higher than the gel temperature. The G′and G″,gel strength ,the gel point and melt point increased at first and then decreased with the content of konjac gum increasing, the maximum synergy was found when carrageenan/ konjac gum was7:3. In addition , pH,sugar and the concentration of KCl had some effect on gel strength, sugar could protect the gel strength in low pH, and the gel strength firstly increased and then decreased with the content of KCl increasing, the maximum was found when the content of KCl was 0.5%. The IR spectra results showed changes were-OH peak migration to the low wavenumber during the gel formation .5 Algin could interact with high-methoxy pectin to form gel, the gel strength was the maximum when the ratio is 3:2.The storage modulus, loss modulus had great relevance with oscillation frequency, and with the M / G ratio of algin decreasing, the relevance was lower. In the same frequency, the storage modulus and loss modulus of by high G was greater than of by high M; while the tanδof by high G was smaller. The addition of sucrose could increase the gel strength properly. The IR spectra results showed that the major structural changes were-OH peak migration to the high wavenumber and C-H and C = O stretching weak during the gel formation.