| Quercus glandulifera Bl.belongs to the genus Quercus.Q.glandulifera Bl.is an acorn-producing shrub,which grows in the provinces of Anhui,Jiangxi,Hunan,and Guangdong,China,i.e.The yield of Q.glandulifera Bl.seeds is high,related products has not formed industrial dimensions,even though Q.glandulifera Bl.seeds are harvested for making tofu by local people.The nutritional composition of Q.glandulifera Bl.seeds was not reported,which caused serious waste.The study chose Q.glandulifera Bl.seeds produced in Jiangxi as raw material,on the basis of the analysis of its nutrition,obtained Q.glandulifera Bl.seed starch by alkaline eluting,then analyzed its proximate composition,particle property,crystal property,swelling power,solubility,freeze-thaw stability,gel clarity,thermal property,pasting property,rheological property,in vitro digestibility and molecular structure.Our aim is ready to provide theoretical basis for exploration and exploitation of Q.glandulifera Bl.seeds.The main results were as follows:1.The moisture content of Q.glandulifera Bl.seeds was 7.55%.Based on a dry weight of seeds,the crude fat,crude protein,dietary fiber,total ash,and nitrogen-free extract contents of Quercus seeds were 4.20,10.16,2.95,0.03,and 82.66%,respectively.Linoleic,oleic,and palmitic were the most predominant fatty acids in Quercus seeds with21.07%,32.98% and 36.11%,respectively.UFA: SFA and SFA: MUFA: PUFA ratios were2.6:1 and 1.25:1.34:1,respectively.Glutamic acid and aspartic acid contents were 8.0mg/100 g and 6.9 mg/100 g respectively,which were the most predominant amino acids in Quercus seeds.The contents of K,Mg,Ca,Fe,Mn and Zn were 2088.92 mg/100 g,102.9mg/100 g,58.2 mg/100 g,11.9 mg/100 g,8.4 mg/100 g and 5.1 mg/100 g,respectively.While the contents of vitamin A and vitamin E were 1.40 mg RE/100 g and 10.78 mg/100 g,respectively.2.Q.glandulifera Bl.seed starch obtained by alkaline eluting had a purity of 98.46%,with 0.59% crude fat of dry matter and 0.95% crude protein of dry matter,and fiber and total ash in starch were not found.Starch extracted from Q.glandulifera Bl.seeds had round,triangle and elliptical morphology with granule size of 3.3–126.2 ?m.The Quercus starch had a typical A-type crystal pattern with 23.53% relative crystallinity,and its amylose content was 25.39%.3.Swelling power and solubility of Q.glandulifera Bl.seed starch increased with temperature increasing,and the sudden change occurred near the gelatinization temperature.2.54% starch paste clarity and 17.50% starch syneresis in freeze-thawstability were found.The gelatinization temperature was 66.53°C,and the transition enthalpy was 4.33 J/g.The peak viscosity,through viscosity,breakdown viscosity,final viscosity,setback viscosity and pasting temperature were 4802 cp,3182 cp,1620 cp,3931 cp,749 cp and 71.87 ?,respectively.4.The static rheological results showed that both 3% and 5% Q.glandulifera Bl.seed starch paste exhibited non-newtonian fluid.The power law model for linear regression fitting suggested the fitting effects of 3% and 5% Q.glandulifera Bl.seed starch paste were rather good,with the fitting correlation coefficient above 0.99.The dynamic rheological results showed that the storage modulus,loss modulus and loss factor increased with increasing temperatures,then sudden decreased near the gelatinization temperature.Q.glandulifera Bl.seed starch consisted of 29.52% rapidly digested starch,12.39% slowly digested starch,and 58.09% resistant starch.Hydrolysis index and glycemic index of Q.glandulifera Bl.seed starch were 40.35% and 42.98% respectively,which indicated the Quercus seed starch belonged to a low GI food.5.GPC chromatogram of Q.glandulifera Bl.seed starch was a continuous curve,in which appeared two obvious peaks,amylopectin and amylose,respectively.Repeated with n-butanol separation and purification obtained amylose and amylopectin of the Quercus seed starch,and HPLC-MALLS-RI analysis suggested the molecular weights of amylose and amylopectin were 5.15×106and 6.71×107g/mol,respectively. |
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