Preparation Of Cassava Cross-linked Starch Octenyl Succinate By Extruder And Its Application

Sodium trimetaphosphate as cross-linking agent , OSA as esterification agent, the cassava cross-linked starch octenyl succinate(CLOSAS) was prepared by extrusion. The properties, structure and the applications of the product were also studied in this paper. Due to simple process, short production cycle, no pollution, low cost, the method of extrusion had large potential market and social value.Effects of sodium trimetaphosphate content, sodium hydroxide content, moisture content, reaction temperature and screwing speed on emulsifying capacity were discussed, respectively. The optimum conditions of CLOSAS preparation were 1.0 % sodium trimetaphosphate,0.6 % sodium hydroxide, moisture 35 %, barrel temperature 120℃, and screwing speed 110 r/min, the emulsifying capacity of the product reached 58.56 % with residue content of OSA was 1.07 %.The physicochemical properties of CLOSAS were studied in this paper. The physicochemical properties included clarity, paste viscosity, water absorption index (WAI) , water solubility index (WSI), lower freeze-thaw stability and capability of anti-retrogradation. The modification decreased transmittance percentage from 19.6 % to 9.97 %. But the claity stability was higher during the storage period compared with native starch. Under the conditions of CLOSAS content 6 %, temperature 25℃, revolving speed 6 r/min, the paste viscosity of CLOSAS by extrusion was 662 mPa.s, lower than that of native starch (29360 mPa.s).But the modified starch paste had better stability against high temperature, shearing and acid. The modification made the WAI of starch from 2.09 % to 9.07 %. WSI from 0.54 % to 12.13 %. The modified cassava starches samples had the lower freeze-thaw stability and the capability of anti-retrogradation, compared with native starches. Esterification and crosslink contributed the starch emulsification capacity. The emulsification stability against high temperature and acid was better.Thc specified structure of CLOSAS was determined by Fr.IR spectrometer. Two new absorption peaks appeard at 1726 cm-1 and 1573 cm-1, respectively, which confirmed that the groups of octenylsuccinate were found in the Fr.IR spectrum .And the absorption peak at 1021 cm-1 was strengthened,which showed that crosslink bond was formed. The SEM photos revealed that granule structure of CLOSAS by the preparation method of extrusion was broken.The spectrometer of differential scanning calorimetry (DSC)and X-ray diffraction(XRD) showed that the crystalline structure of cassava starch was destroyed.The application of CLOSAS in emulsified banana flavor as an emulsifier and a stabilizer was studied. Effects of the CLOSAS content, banana flavor content, emulsifying temperature and emulsifying speed on the stability of the banana flavor emulsion were discussed. The optimum conditions of banana flavor emulsion preparation were content of CLOSAS 12 %, content of banana flavor 4 %, emulsifying temperature 30℃, emulsifying time 4min, and stirring velocity 4000 r/min, the stability of the banana flavor emulsion was 0.0293.