Studies On The Desalination, Characteristics And Application Of Salted Duck Egg White

Salted duck egg is the characteristic egg product in China, the salted duck egg yolk is often used as the raw material of moon cake, dumplings and some dishes for its unique flavor, appealing color and characteristic texture. Salted duck egg white is a high quality protein source with many functional properties and nutrients, while they are often abandoned by food processors because of the high salt content, which is not only a wastage of high quality protein, but also results in an environmental pollution. This paper mainly focused on the study of desalting process of salted duck white and making full use of it; finding the right ultrasound power, and best dilution ratio of duck egg white for the vacuum of ultrafiltration the first way is applying the desalted duck egg white powders to the noodles which obtained from pulse spouted microwave freeze drying. Second way is combined with acid hydrolysis and enzymatic hydrolysis to hydrolysis desalted duck egg white making high quality amino acid content sauce.Firstly, the effects of microwave power, ultrasonic power, egg white liquid dilution ration, ultrafiltration vacuum on desalination of salted duck egg white which took the desalination rate and the protein recovery rate as the index. On the basis of single factor experiment design orthogonal experiment to optimize the desalting process conditions. The results showed that the effect of microwave is not good, and in a certain range, the desalination effect becomes better with the increase of ultrasonic power, egg white liquid dilution ratio and the vacuum of ultrafiltration. The orthogonal experiment results show that the order of desalination effect of different factors were: ultrafiltration vacuum>dilution ratio >ulrasound power. Hence, we can conclude that we could get the desalination up to 95.5% and the protein recovery was about 90% when the dilution ratio is 4 times, the ultrasound power is 900 W, the ultrafiltration vacuum is 0.09 MPa.Secondly, the comparative study of vacuum freeze-drying(FD), pulse spouted microwave freeze drying(PSMFD) and high-speed centrifugal spray drying(SD) on the functional properties, and taking the color, microstructure, foaming properties and foaming stability, the emulsifying properties and emulsifying stability, gel properties of the desalted duck egg white as the index. The results showed that the drying time of FD was the longest(12 h), and the color of the product was the best, followed by PSMFD method, which was 5 h, and the shortest was SD, which is instantaneous, the color was somewhat yellow because of the high temperature. PSMFD duck egg white powder had the microstructure with porous network, FD duck egg white powder kept microstructure with good overall shape, while the SD duck egg white powder had the macroporous spherical or ellipsoidal particles of the microstructure. For the functional properties, comparing to FD and SD, PSMFD products had the better foaming property, emulsifying property and gel property than that of FD and SD products. In terms of Comprehensive drying time and physicochemical and functional properties, we finally choose PSMFD as the desalted duck egg white drying method, and applied it in high quality noodles, which showed that when the adding quantity was 3%, the desalted duck egg white powder could significantly improve the cooking quality and sensory quality of noodles.Finally, the study was to investigate the effects of combined method(acid hydrolysis and enzymic hydrolysis) hydrolysis the desalted duck egg white preparing the high content amino acid sauce. The effect of acid concentration, the temperature and the time of hydrolysis on the hydrolysis process of desalted duck egg white were also studied. The results showed that the hydrolysis degree increases with the increment of acid concentration, the temperature and the time of hydrolysis. When the acid concentration is 6 mol/L, the acid hydrolysis time is 4 h, the enzymatic hydrolysis time is 2 h, we could reach the best hydrolysis degree of 52.66%, which contains 17 kinds of amino acids, the essential amino acid content as high as 36.95%, and the fresh, sweet amino acid was as high as 60.3%.