| The impact of cyclodextrins on the gelling properties and gel temperature were studied by added different concentrations ?-CD,?-CD,?-CD,HP-?-CD and M-?-CD into ?-carrageenan,and then the paper explored the application of ?-carrageenan and ?-CD in sugar-free gel preliminarily.The effects of ?-carrageenan concentration and four types of ions concentration on the properties of ?-carrageenan gels were studied by means of texture and rheological analysis,including K+,Na+,Mg2+ and Ca2+.The results show that with ?-carrageenan concentration increased,the hardness,gumminess and chewiness were enhanced,and the elasticity increased first and then decreased,however,the cohesiveness of gel was no significantly affected by the?-carrageenan concentration.K+,Mg2+ and Ca2+ led to a stronger gel,but when ions concentration more than 0.2%,the gel brittleness increases and the elasticity decreases.However,the gels texture properties at Na+ concentrations from 0.1% to 0.5% had no significant change.The order of influenced of four kinds of salt ions on the gel properties of ?-carrageenan was K+>Ca2+> Mg2+> Na+.Higher K+ concentrations led to higher gelling temperature,while with Ca2+,Na+ and Mg2+ concentrations increased,the gelling temperatures were increased,but the temperature rises slowly.When the salt ions concentrations were 0.2%,the order of influenced of ions on gel viscosity of ?-carrageenan was Ca2+> Mg2+> K+ >Na+.Through the study of the properties of ?-carrageenan/cyclodextrins/water gel,it was found that cyclodextrins had a significant effect on the texture of ?-carrageenan gel.?-CD,?-CD,?-CD parent cyclodextrins reduced the gel hardness,while HP-?-CD and M-?-CD increased with the increase of hardness first and then decreased slightly.Cyclodextrins enhance the gel elasticity,chewiness and adhesiveness,while cohesiveness is not significantly affected.The rheological results show that cyclodextrins has a promoting effect on the gelation temperature of ?-carrageenan.The apparent viscosity of 5 cyclodextrins?mass fraction 3%?decreased with the increase of shear rate.The apparent viscosity was in the order of ?-carrageenan >?-CD >?-CD >?-CD > HP-?-CD > M-?-CD.The results of FT-IR test showed that the network structure of the ?-carrageenan/cyclodextrins/water gel system was formed,based on the network structure of ?-carrageenan,and between ?-carrageenan and cyclodextrins molecules exist interaction.The results of TGA showed that the weight loss rate of ?-carrageenan was 39.69%,the decomposition temperature was about 223.17 ?,and the thermal stability of ?-carrageenan/cyclodextrins/water gel system was significantly improved.SEM results show that the structure of the cyclodextrins are dispersed in the framework of the ?-carrageenan,and the gel wall layer becomes smooth.The results of freeze-thaw stability test showed that the water content of ?-carrageenan/cyclodextrins/water gel was increased from 9% to 56%.The optimum process of preparing sugar-free edible gel was studied by single factor test and response surface test using kappa carrageenan,?-CD,xylitol and citric acid as raw materials.The optimal conditions for the preparation of sugar-free gel were as follows: the amount of ?-carrageenan was 0.7%,?-CD was 1.92%,xylitol was about 16.87%,and citric acid was about 0.2%,and at this point the hardness and elasticity of the sugar-free gel were 1.70 N and 12.065 mm.?-carrageenan/?-CD gel sugar-free edible gel preparation,effects of ?-carrageenan on sugar-free gel hardness and elasticity were significantly?P<0.05?,and the amount of ?-CD,xylitol,citric acid on the hardness and springiness of the gel had no significant effection.While the freeze-thaw stability of sugar free gel improved from 20% to 30%. |
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