Isolation of a phospholipid fraction from inedible egg

Abstract

During processing of eggs, large amounts of waste material (feed grade or “inedible egg”) are also produced. The amount of “feed grade egg” that the US industry generates from processing operations is estimated to be approximately 2% of the egg production. Researchers are challenged to investigate potential new uses of this by-product. With nearly 80% of the total phospholipids present in egg being phosphatidylcholine (PC), inedible egg constitutes an inexpensive source of an ingredient with high nutritional and functional properties. Our objective was to optimize and improve existing methods to isolate an enriched phospholipid fraction from dry inedible eggs by selective supercritical fluid extraction (SFE). A phospholipid-rich fraction was successfully extracted with a unique two-step process, consisting of a first step with CO 2 and a second step with ethanol as co-eluent. In an effort to optimize the extraction conditions of the first step, pressure, CO 2 flow rate and temperature effects were investigated. Various times of extraction were also employed to obtain the highest concentration of PC in the residual egg powder with the highest elution of unwanted neutral lipids. Optimal conditions to achieve the highest retention of PC in the dried egg were found to be 41.4 MPa pressure, CO 2 flow rate of approximately 5 l/min and 45 °C sample temperature. A second step with a SFE with CO 2-containing ethanol as modifier resulted in elution of a fraction rich in PC. The yield was estimated to be approximately 49 g PC/kg of dried egg. Results presented demonstrate that supercritical fluid extraction can lead to the isolation of a value-added ingredient from a by-product of the egg industry.