Effects Of Konjac Glucomannan On The Thermodynamics And Gelatin Texture Of Potato Amylose, Amylopection And Their Mixtures

Based on chain fragment and molecule level, food polymer science theorycombining with modern instrument analysis technique were applied to investigatedeeply effects of molecular characteristics of konjac glucomannan (KGM) on thethermodynamics, crystalline property and gelatin texture of amylose andamylopection. This will provide the important and solid theory foundation. The mainconclusions are as follows:1. Study on the molecular characteristics of KGM was carried out byhigh-performance size exclusion chromatography (HPSEC), multi-angle laser lightscattering (MALLS). The results were M_w=1.040×10~6g/mol, M_n=9.395×10~6g/mol,M_z=1.329×10~6g/mol; Rn=110.5nm, Rw=115.9nm, R_z=129.6nm. The polydispersityindexes of M_w/M_nand M_z/M_nis1.107and1.414, respectively. Besides, based on theslope of the conformational plot of KGM being0.40±0.00, we suggest that KGM isbelieved to be a highly compact and branched polymer. The results of the presentwork imply that it will be beneficial to not only further research on the relationshipbetween molecular characteristics and functionalities of KGM, but also extend theapplication of KGM to agricultural, food and medicine fields and so on. Compareingwith amylose and amylopectin, KGM has a lot of molecular chain with pendant groupwhich is neither symmetry nor clear and neat, for what, the section of pendant groupis much bigger than others. And the pendant group also not flexible which has makegood performance in blocking the activity of chain segment and effect the speed ofpervasion when the chain segment permutated. So, the speed of crystallize and thedegree of crystallinity is low.2. Differently compositive of amylose, amylopectin and KGM have the sameglass transition temperature, this Tg changed with the contain of components and thevalue of which just between the glass transition temperatures of every compositions,that can help to make a conclusion: this high polymer will have a good compatibilityunder the inverse proportion.3. The Tg of amylose/KGM and amylopectin/KGM reduced with the increase ofthe KGM, The Tg increased with the extend of the keeping time. The more the KGMadded the little of the Tg will be. Those result expose that KGM can make goodperformance in reduce the recrystallization of amylose and amylopectin.4. The addition of KGM could increase the firmness, cohesiveness and index of viscosity of amylose, while decrease its consistency. The addition of KGM couldincrease the consistency, cohesiveness and index of viscosity of amylopectin whilethe firmness of amylopectin was decreased. When the amylose/amylopectin ratio was1:1and the concentration of KGM was more than0.03%, the firmness of the mixedamylose/amylopectin/KGM gelatin was increased with increasing concentration ofKGM. In addition, the addition of KGM could increase the consistency, cohesivenessand index of viscosity of the mixed amylose/amylopectin/KGM gelatin. When theamylose/amylopectin ratio was1:2, the addition of KGM could increase the firmness,cohesiveness and index of viscosity of the mixed amylose/amylopectin/KGM gelatin.When the amylose/amylopectin ratio was1:3, the addition of KGM had hardly anyremarkable influence on the firmness and cohesiveness of the mixedamylose/amylopectin/KGM gelatin, while the addition of KGM decreased theconsistency of the mixed amylose/amylopectin/KGM gelatin and increased the indexof viscosity of the mixed amylose/amylopectin/KGM gelatin.