Study On Fine Structure, Digestion And Water Mobility Of Lotus Root Starch In Different Periods

The paper was to systematically investigate the structural characteristics and properties of lotus root starches,and make correlation analysis of its granular properties, fine structures,physicochemical properties and digestion properties by taking lotus root starches of different growing periods as the raw material,and using modern analysis methods.It also investigates the effect of water-starch interaction on lotus root starch by using nuclear magnetic resonance technology.By the comparison of the the three fine structures of lotus root starch in different growing periods,it explains the effect of fine structure of lotus root starch on the granular properties,physicochemical properties and digestion properties from microstructure.By the comparison of the digestion property of starch with and without anthocyanins,it provides theoretical basis for the anthocyanins’ effect on starch digestion.The major results are follows:1 The composition and granular properties of lotus root starch in different growing periodsThe composition of lotus root starch in different growing periods is different,and with the increase of its maturity,its ashc content increases.The amylose content of lotus root starch in different growing periods is respectively 21.04%、22.45%and 25.27%.The granular properties of lotus root starch in different growing periods have been characterized by the means of X-ray diffraction analysis,granule size analysis and thermogravimetric analysis,the results were as follows:the crystallinity of lotus root starches is respectively 26.33%、27.32%and 32.77%;the size of rice starch granules range of mean diameter is respectively 22μm、27μm and 30μm;the activation energy of lotus root starches degradation is respectively 189.6 kJ/mol、190.5 kJ/mol and 192.6kJ/mol.2 The physicochemical properties of lotus root starch in different growing periodsThe physicochemical properties of lotus root starch were studied,including solubility and swelling power,thermal properties by differential scanning calorimeter (DSC).The range of solubility and swelling power is respectively 10.09%、13.51%and 15.38%and 28.03 g/g、31.98 g/g、34.23g/g,respectively.The range of initial transition temperature,peak transition temperature and conclusion transition temperature by DSC were 58.5.4-59.6℃、62.7-65.2℃and 67.0-70.4℃,respectively.3 Digestion of lotus root starch in different growing periodsThe glycemic index is used to estimate In vitro lotus root starch digestion.The range of GI(native starch) is between 57.22 to 59.52,the range of GI(gelatinized starch) is between 81.39 to 86.00,the range of GI(retrogradation starch) is between 74.49 to 76.79.Under enzymatic hydrolysis condition,the hydrolysis of lotus root starches reaches equilibrium after 90 min and hydrolysis continued slowly.The gelatinized and retrograded lotus root starches are high GI food.By the comparison of the digestion property of starch with and without anthocyanins,it indicates that the anthocyanins can restrain the digestibility of lotus root starch.4 Fine structure of lotus root starch in different growing periodsThe distribution of branch chains length in amylopectin was determined by high performance anion exchange chromatograph,showing Gaussian distribution.The amylopectin branch chains length ranged from degree of polymerization DP 6 to DP36. The long branch chain(DP＞36) content was about 2%,the relative amount of amylopectin chains with DP 12-23 was about 69%.The experient on DP of amylose by chemical methods shows that:the average DP of amylose ranged from 4190 to 8850.5 The effect of Water mobility and the gel property of lotus root starch in different growing periodsThe experiment of the peeling and section puncture test on lotus root in different growing periods indicates that:with the increase of maturity,its rupture force and fracture energy decrease.The experiment of the gel property of lotus root starch TPA test(1:5) indicates that:the gel properties of lotus root starch in different growing periods have large difference in the same condition;while the gel properties of lotus root starch in the same period but under different conditions also have large difference.The experiment of lotus root starch with different water content(1:2 1:5) NMR test shows that:the relaxation time of starch with different water content have different trend;the relaxation time of lotus root starch with the same water content but in different growing periods have approximately same trend.