Studies On The Properties Of Two Different Types Of Texture Of Lotus Root

Lotus root is various in species and in texture, it can be divided into two main categories, one type is Farinose lotus root, another is Crisp lotus root. The research is based on the two different types of texture of lotus root. First, Select two Farinose lotus root varieties and two Crisp lotus root varieties (December 2009) as the experimental material representatively. Studied on the differences between sensory and composition of lotus root. Furthermore, studies on the morphological and rheological properties of starch separated from lotus roots. Second, research on the cooking characteristics of Farinose lotus root and Crisp lotus root(March 2010), to explore the changes of sensory, composition, cell structure and other aspects during cooking. Finally, seven different varieties of lotus root as material, to determine their main components at different harvest period (August 2010, October 2010 and December 2010), to explore their content variation, Furthermore, compare the differences of microstructure, paste, gel of lotus root starch (December 2010).The main results are as follows:1. The morphology and chemical composition of four different lotus root varieties have significant difference.1# and 3# are Farinose lotus root varieties,2# and 4# are Crisp lotu root varieties. In Farinose lotus root varieties, L-value of scarfskin and sareocarp, a*-value, hardness of sarcocarp, cellulose content, total phenol content, starch content, amylose and amylopectin content, the ratio of amylopectin and amylose are higher than that of Crisp lotus root varieties, but moisture content is lower than that of Crisp lotus varieties. Farinose lotus root taste waxy.Starch isolated from 1# showed the bigest granule size and maked up a larger percentage of large granules, while starch from 3# showed the smallest granule size and maked up a larger percentage of small granules.2# and 4# have similar morphology.1# starch showed the highest G', G",ΔG' and lowest tanδ, TG'max during heating, also have the highest G', G" and lowest tanδduring cooling. while,3# starch showed the opposite trend with 1# strach.The rheological parameters of 2# and 4# between 1# and 3#. It can be concluded that rheological differences of stach have relations with particle morphologyThickening coefficient increases with increasing concentration(4%-8%) of lotus roots starch paste, Flow coefficient of all starch paste at different concentration(4%-8%) is at around 0.3, they are all pseudo plastic fluid. The viscosity decreased with the increasing shear rate. At the same shear rate and concentration, the shear stress of starch paste vary with the different varieties, but viscosity variation of different starch paste is not obvious.Study on starch gel texture of different lotus root. The hardness and chewiness of starch gel of Farinose lotus roots is lower than that of Crisp lotus roots, adhesiveness is higher than that of Crisp lotus roots. Water-binding capacity (WBC) of starches from different lotus root varieties are differernt. Turbidity of gelatinized aqueous starch suspensions from all lotus root varieties increased with storaging in five days at low temperature, Changes of turbidity has relations with particle morphology.2. After cooking Farinose lotus roots and Crisp lotus roots for different time, L-value, hardness, chewiness, cohesiveness of sareocarp, drysolid content, soluble sugar content, VC content, cellulose content, pectin content, total phenol content are in a tendency to decrease, but a*-value of sarcocarp is increase, Farinose lotus root and Crisp lotus root have different rangeability.Study on antioxidant capacity changes of Farinose lotus root and Crisp lotus root through cooking by different methods, antioxidant capacity of lotus root decreased by boiled and microwave treatment. Boiled treatment make antioxidant capacity fall the most, Stir-fried treatment make the antioxidant capacity increased slightly. The time of boiled treatment has an impact on cell structure. Effect of cooking time on cell damage is Farinose lotus root more serious than that of Crisp lotus root.3. Changs of L-value, a*-value, hardness of sareocarp in each varieties are significant difference at August and October, but, at December, all Farinose lotus root varieties are higher than Crisp lotus root varieties. The content of moisture of seven different lotus root varieties is in a tendeney to decrease with the extension of harvest, but cellulose content, starch content,amylose content,amylopectin content and protopectin content are in a tendeney to increase.Soluble sugar content and soluble pectin content are in a tendeney to increment first, then decrease with the extension of harvest, while total phenol content increased first, then decreased. Changes of L-value of scarfskin and Soluble protein are no evident regularity.The morphological properties of starch separated from seven sorts of lotus roots are similar, However, there are still some differences among varieties. G', G" of Farinose lotus root varieties are lower than that of Crisp lotus root varieties during heating and cooling, while ToG' and TG'max are higher than Crisp lotus root varieties. Amylose content of Crisp lotus root strach is higher than that of Farinose lotus root and amylose content has an impact on Modulus during heating and cooling. There is a positive significance correlation between amylose content and G'max, G"max, G'100℃G"100℃, G'25℃...