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Abstract
In 1993, the NutraSweet company introduced a commercial low cholesterol dried yolk product that used supercritical carbon dioxide extraction $\rm (SCCO\sb2)$ technology. Although, the company decided to terminate production of the product in 1996, the potential to commercialize the product still exists. Due to the high cholesterol and lipid content in the egg yolk, oxidation is highly possible during the extraction process. The overall objective is to test the effects of the $\rm SCCO\sb2$ extraction process on cholesterol and lipid oxidation, and to identify changes in lipid and phospholipid components of spray dried egg yolk during the process. In addition, this study will evaluate the effectiveness of different antioxidants during $\rm SCCO\sb2$ extraction. Antioxidants, ascorbyl palmitate plus $\alpha$-tocopherol (5:1, w/w), Tenox-GT2 or BHT were added into the liquid yolks at 0.02%, 0.02%, and 0.01% levels (w/w) before the drying process. The extraction conditions were set at 306 atm and $\rm 45\sp\circ C.$ Results indicate that approximately one third of total detectable cholesterol oxides were removed from the dried egg yolk by $\rm SCCO\sb2$ extraction $\rm (p < 0.05).$ Tenox GT-2, appeared to decrease the formation of $7\alpha$-hydroxycholeserol during the extraction but not affect other cholesterol oxides. Phospholipid content was concentrated by $\rm SCCO\sb2$ extraction. In general, antioxidants appeared to minimize degradation of phospholipids and fatty acids during the $\rm SCCO\sb2$ process. This study also showed the potential of using $\rm SCCO\sb2$ extraction process to eliminate the containing of cholesterol oxide in dried egg yolk products.
