Optimization Of Alkali Extraction And The Physical And Rheological Properties Of Corncob Pectin

Pectin is a kind of food additive that is usually used as a thickener and stabilizer in food industry.Some pectin is extracted from apple and citrus to improve the sensory quality of soft drinks in food industry.Nowadays,corncob is used as raw materials to study.In this thesis,the optimum extracting process of corncob pectin would be built up,then compare to the changes of its microstructure,chemicals,physics and rheology.Results and conclusions as follows:1 Compared to the extracting effects of three solvents on corncob pectin,the optimum extracting conditions were 3%NaOH with 1:30 W:V during 10h,2.5%Na2CO3 with 1:25 W:V during 6h and 3%NaHCO3 with 1:30 W:V during 7h.In all of them,NaOH was the most suitable solvent for extracting pectin from corncob.Thr pectin yet is up to 23.71%and its concentration is about 36.13%.2 After NaOH treatment,mostly hemicelluloses and partial cellulose were degredated and some pectin was dissolved.When corncob pectin was tested,it was consisted of D-GalA,D-Xyl and L-Rha as lest.It belonged to polysaccharide.3 As pectin esterification,rotation and refraction,they were 60.7%,-0.29 and 1.33,respectively.For these reasons,corncob pectin was a high-ester with L-type polysaccharide.4 The corncob pectin rheology followed as the Power Law model.Its equation is suitable for Y=kXn and its power-law exponent was n<1.So this pectin belonged to Pseudoplastic non Newtonian fluid with shear thinning phenomenon.Therefore,the corncob pectin can be developed a new resource of food's thickener and stabilizer.