The Rheological Properties Of Okra Extract And Its Saliva Mixtures

Okra presently gains its market share.Most previous studies focused on the analysis of agricultural cultivation,fruit storage,fruit and nutrient composition analysis and the extraction and application of okra polysaccharide.There has been little studies on rheological properties,both shear and extensional of okra polysaccharides and in particular their saliva mixtures.In order to further develop the potential values of natural resources of okra,this work will conduct a thorough investigation of shear and extensional rheology of okra mucilages,in order to obtain information on this hydrocolloid's mechanical behavior at a molecular.Along with a throughly analysis on the shear and extensional characters of okra polysaccharide and human saliva mixtures and artificial saliva mixtures,this work will provide a good understanding after oral behavior of this specific hydrocolloid and provide basic rheology data for designing of artificial saliva formulations.Main conclusions are listed below:(1)Okra polysaccharide exhibit high shear viscosity,especially at pH 7 as compared to at pH 4.Their character is predominantly elastic throughout the shear rate tested in this work.Superposition of the oscillation and shear plots suggests the existence of colloidal interactions both at pH 4 and pH 7.The viscosities are lower at pH 4 due to the aggregation of polymers into fewer,larger,entities.The extensional viscosities were found to be much higher than the respective shear viscosities,the Trouton,which is the ratio of extensional viscosity and shear viscosity,decrease with increasing concentration.(2)Incorporation of okra polysaccharide(OP)solutions in human saliva(HS)interferes with the self-assembly of salivary mucins and have detrimental effects on the low-shear viscosity of the mixture.Shear-induced interactions occur between the mixtures,as can be seen from the negation of complex viscosity and apparent viscosity.The Trouton ratio values are in the order of hundreds,suggesting that extensional viscosity dominates the overall behavior of OP and HS mixtures.Extensional and shear flow are equally important concerning the OP-HS elastic behavior as shear elastic module extensional elastic module are on the same order.(3)Incorporation of okra polysaccharide(OP)in an artificial saliva(AS)positively synergy with the self-assembly of artificial saliva and increase the viscosity of mixtures.Particle sizing analysis gives no indications of enthalpically-driven OP-AS interactions.Their character is predominantly elastic throughout the shear rate rage.Cox-Mertz plots suggests the existence of interactions between the two OP and AS.Extensional viscosity dominates the overall behavior of mixtures,with the Trouton ratio in the order of hundreds.Extensional and shear flow are equally important in terms of the OP-AS elastic behavior.