Reduction of Cholesterol in the Spray Dried Egg Yolk by Super Critical Carbon Dioxide Extraction

Abstract

The reduction of cholesterol in the spray dried egg yolk was studied by using supercritical carbondioxide extraction. Cholesterol contents were determined by gas chromatographic method (GC). The cholesterol content in dried egg yolk had mean value of 2321.40 mg cholesterol/100 g test sample. A statistical 33 factorial experiment in completely randomized design was performed to study the effect of factors in reduction of cholesterol in the spray dried egg yolk by supercritical carbondioxide extraction. These factors were 3 levels of CO2 temperature : 40°C, 45°C and 50°C, 3 levels of CO₂ density : 0.70 g/ ml, 0.80 g/ml and 0.90 g/ml and 3 levels of extraction time : 30 min, 45 min and 60 min respectively. The residual content of cholesterol in the spray dried egg, after extraction was determined by GC. Duncan’s new multiple range test (DMRT) was used to differentiate treatment means. The results indicated that the factors effecting the extraction of cholesterol in the spray dried egg yolk were CO₂ density, CO₂ temperature and extraction time, respectively in order of importance. Response surface methodology (RSM) was used to determine optimum condition of cholesterol extraction. The processing conditions of 50°C temperature, 0.90 g/ml density, 350 bar pressure and 60 min extraction time gave the optimum condition of cholesterol extraction at 64.07 %. Supercritical carbondioxide extraction of the spray dried egg yolk had dramatic effect on proximate composition of the end product. The protein content increased 19.53 % and phospholipids content increased 18.74 %, but total lipid content reduced 17.39 %. The solubility value and emulsifying capacity value of the treated spray dried egg yolk were 16.31 % and 292.05 ml of oil/g protein, respectively. Consumer acceptability test indicated that the treated spray dried egg yolk can produce emulsifying product of good quality comparable to the fresh egg yolk.