Colloidal Stability Of Sesame Paste And Water Adding And Mixing Process During Aqueous Extraction Of Sesame Oil

Firstly, based on tradtion aqueous extraction technique, sesame paste sampleshaving different particle sizes were produced by manually controlling the milling rates.Then the experiment mainly studied the relationship between particle size distributionof sesame paste and colloidal stability and rheological propertie.Secondly, sesame oilwas extracted by tradtion aqueous extraction method, aqueous enzyme-assistedextraction method and aqueous ultrasonic-assisted extraction method. The optimumprocess conditions were determined.Enzyme and ultrasonic were applied in thesolid-liquid separation. It is innovation in oil extration. On basis of the single-factorexperiment, the orthogonal trial was used in optimization of technological parameters.Finally, the exeperiment discussesed effects of different press processings on thequality of sesame oil. The quality of the aqueous extraction sesame oil was analyzed,and compared with that of screw press method sesame oil and hydraulic press methodsesame oil. In addition, the oxidation stability of sesame oils was determined.The results are as follows:（1） Multimodal particle size distribution determined using laser-scatteringanalyzer was observed for paste samples. It was detected that colloidal stability ofsesame paste was improved by decreasing the median particle size below8.98μm. Thecolloidal stability of sesame paste was decreased with the increase of the temperature.The Non-Newtonian pseudo plastic behavior was observed for all sesame pastesamples. Consistency coefficient and temperature can be described by the Arrheniusequation. Shear rate and the apparent viscosity were described by power law model.Particle size distribution has a significant effect on the relative viscosity, under thesame conditions, the apparent viscosity was decreased with decreasing particle size.（2）On basis of the single-factor experiment, the orthogonal trial was used inoptimization of technological parameters. The optimum process conditions weredetermined. Sesame oil was extracted by tradtion aqueous extraction method, aqueousenzyme-assisted extraction method and aqueous ultrasonic-assisted extraction method,the optimum process conditions were determined. The optimum conditions of tradtionaqueous extraction method sesame oil was determined: the ratio of solid and liquid0.8g/ml (v/w), the temperature of extraction70℃, and the extraction of pH5.0.The extracting ratio is82.48%. The optimum conditions of aqueous ultrasonic-assistedextraction were solid-liquid ratio0.8ml/g, ultrasonic of time15min and ultrasonic ofpower600W. Under these conditions, the extraction rate was up to88.28％. Theoptimum conditions of aqueous enzyme-assisted extraction of sesame oil was theextraction temperature of50°C, the extraction of pH of7.0, and extraction time of3h,the ratio of solid and liquid of1.0ml/g. Enzyme hydrolysis was performed withcomplex enzyme of papain800U/g, trypsin400U/g and cellulase150U/g per gramoilseed, the extracting ratio is87.58%. Three extraction method processes werecompared, both ultrasonic and enzyme assisted improve the yield efficiency; aqueousultrasonic-assisted extraction was effective.（4）The endogenous antioxidants in screw press method sesame oil: sesaminwas454.02mg/100g, and sesamol was156.26mg/100g and γ-tocopHerol was126.14mg/100g; The endogenous antioxidants in hydraulic press method sesame oil: sesaminwas736.21mg/100g, sesamolin was317.56mg/100g and sesamol was156.26mg/100g and γ-tocopHerol was106.89mg/100g; The endogenous antioxidants inaqueous extraction method sesame oil: sesamin was703.47mg/100g, sesamolinwas181.00mg/100g and sesamol was4.90mg/100g and γ-tocopHerol was26.66mg/100g.