The Studies On Effects Of Low Temperature Extraction Process On Qualities Of Sesame Oils And Sesame Meals

The white sesame seeds were chosen as raw material. The effects of two low-temperatureextraction techniques (sub-critical fluid extraction (SCFE) and supercritical fluid extraction(SFE)) on oil yields and composition of the oil and the protein meal. The conclusions were asfollows:The process conditions of supercritical CO2extraction sesame oil were optimizedthrough single factor experiments and orthogonal experiments, and obtained the optimumextraction parameters as follows: material-to-liquid ratio4:50(W/V), temperature60℃,pressure50MPa, CO2flow rate7L/min, extraction time5h. Under the optimum conditions,the oil yields of unpeeled sesame seeds and pealed sesame seeds were reached86.7%and89.3%, respectively. Meanwhile, the effects of extraction temperature, extraction pressure onthe content of antioxidants in sesame oil were studied. The results showed that: the extractionefficiency is better when at35℃or35MPa, the yields of sesamin were64.7%and69.0%, theyields of sesamolin were76.3%and80.8%, respectively, and all higher than the yields ofsesame oil.. Tocopherol content of sesame oil was rise after the first fall with increasingtemperature or pressure.Effects of12kinds modifiers on extraction rates and antioxidant contents of sesame oilwere studied using CO2extraction as control group. The results showed that the yields ofsesame oil increased with addition of different modifiers, and ethyl acetate,which was the bestone amomg them, had15.0%higher then control group, but the contents of sesamin,sesamolin and tocopherol were lower than their contents in oil extracted by pure CO2.Optimization of SCFE process conditions were performed by single factor experimentsand orthiginal experiments, and the optimum extraction parameters were as follows:temperature50℃, extraction time30minutes, and material-to-liquid ratio1:4. Under theoptimum conditions, the oil yield of unpeeled sesame seeds and pealed sesame seeds werereached95.3%and95.6%, respectively.Effects of five extraction techniques including SCFE, SFE, cold pressed (CP), aqueous extraction (AE) and screw pressed (SP) on the sesame oil and sesame meal were studied. Theresults showed that: the yields of SCFE and SFE were reached86%, the yields of the otherswere less than80%; The sesame oils, which extracted by SCFE, SFE and cold-pressedprocess, had a high contents of three antioxidants and they had many other qualities (includedlight color, the contents of peroxide value and phosphorus), acid value was decreased afterpeeling. Sesame oils by AE and SP had a good flavor and greater oxidation stability, but colorwas darker and the contents of antioxidants had decreased. The NSI values of sesame mealsobtained from SCFE, SFE and cold pressed were between8.7%~12.6%, the NSI value ofsesame meal obtained from SP was particularly low (4.8%) and the NSI value of AE meal was19.5%. The compositions of amino acids in sesame meals obtained from SCFE and SFEextraction processes have no change compared with compositions in raw sesame seeds,indicated that SCFE and SFE have no affect on composition of the amino acid. The essentialamino acids in these meals were close to recommended values of FAO and WHO, whichshowed that sesame meals obtained from SCFE and SFE have a high nutritional value. Thecontents of lysine (the first limiting amino acid of sesame) in meals obtained from AE and SPdecrease from3.20%to1.63%and1.67%, respectively, which indicate a poor nutrition valueof protein.