Studies On The Preparation And Properties Of Corn Starch Toothpick

The preparation and properties of corn starch toothpick adding oxidized corn starch, cross-linked corn starch, oxidized-crosslinked corn starch and crosslinked-oxidized corn starch were studied.The properties of modified corn starch were studied. The gel's transparency of oxidized corn starch and crosslinked-oxidized corn starch increased with the amount of carboxyl content. The gel's viscosity of oxidized corn starch, cross-linked corn starch, oxidized-crosslinked corn starch and crosslinked-oxidized corn starch increased with temperature decrease. The modified starch gel's belonged to non-Newtonian fluid, were shear-thinning. For oxidized corn starch and crosslinked-oxidized corn starch, the amylose content first decreased and then increased as the carboxyl content increased. For cross-linked corn starch and oxidized-crosslinked corn starch, the amylose content did not change with the cross-linking degree.The preparation of corn starch toothpick was studied. The factors which had influence on the shear stress of corn starch toothpick which was prepared by adding different modified starch were also studied, such as drying method, colding time, the moisture of paste, the kind and addition of plasticizer. It has been found that the shear stress of corn starch toothpick got maximum 1.680×105g/mm2 under the following optimal conditions: making dough by mixing the corn starch, 20% of oxidized-crosslinked corn starch(carboxyl content of 0.2125%, cross-linking degree of 178.4%, for gelatinization, corn starch dry basis), every 100g corn starch(corn starch dry basis) with 10mL glycerine and regulating water for 47.37%(of which 50.00% for gelatinization, corn starch dry basis), extruding, forming, oven drying at 45℃after colding for 4h at -4～0℃.The properties of corn starch toothpick were studied. The transparency of corn starch toothpick increased as glycertine,oxidized corn starch,oxidized-crosslinked corn starch and crosslinked-oxidized corn starch were added. The elasticity was improved as modified corn starches were added. There was no correlation between shear stress and elasticity. The shear stress of corn starch toothpick dipped in water for 5~30minutes which was made by adding oxidized corn starch or crosslinked-oxidized corn starch decreased faster than adding cross-linked corn starch or oxidized-crosslinked corn starch. The degradability of corn starch toothpick which was made by adding oxidized corn starch or oxidized-crosslinked corn starch was better than adding cross-linked corn starch or crosslinked-oxidized corn starch. Under optimal conditions the transparencies, shear deformation, breaking time of corn starch toothpick by adding oxidized-crosslinked corn starch were: 6.7%, 0.624, 12.92min respectively.Corn starch toothpick was analyzed by FTIR for structure investigation. The band at 995cm-1 and 1022cm-1 increased, the 1047cm-1 decreased, compared corn starch toothpick by adding oxidized-crosslinked corn starch to native corn starch toothpick. It was suggested that the increasing band of 995cm-1 could be associated with strengthen of intermolecular hydrogen bond, the increasing band of 1022cm-1 could be associated with the increase of amorphous, the decreasing band of 1047cm-1 could be assumed the loss of crystalline.