The Study Of High Gel Strength Egg White Powder

Egg White (EW) has good ability of gelling while fresh EW can not be stored for a long time, after being processed into Egg White powder (EWP) it can be used as a kind of safe and convenient additive in many fields. Nowadays, people pay more and more attention on the EWP with special functional properties. On the basis of prevenient study in this area, many methods were used to improve the gel strength of egg white powder such as dry-heating, microwave radiation and Maillard reaction, so as to widen its application in food industry.The rheology character and effects of medium on the gelling property of EWP were discussed which showed that the gel structure developed when temperature approached 72℃; the gel strength increased according to the increase of protein concentration, and when the pH of EWP solutions was adjusted to 4.0 and 9.0 the gel strength was higher. However, the gel formed at pH 2.0-3.0 was the softest. When pH reached 4.0 the gel strength dramatically decreased with the addition of NaCl.The process of dry-heating was investigated. The environmental relative humidity was controlled below 51%, after being dry-heated at 80-110℃for several days dry-heated egg white powder (DH-EWP) could form a gel whose hardness increased from 650 g to 2500 g. The gel form temperature of DH-EWP was 65℃.Microwave radiation method was firstly used to modify the EWP for high gel strength. The microwave radiated egg white powder (MR-EWP) was radiated under 600W work powder for 130s and it could form a gel with strength at 1300 g, gel form temperature at 70℃. Study of hydrophobicity, free sulfhydrxyl groups, molecular weight, secondary structure of MR-EWP and EWP indicated that the proteins were partly denatured and polymerized.Maltodextrin as raw material, Maillard reaction was firstly combined with fermentation in order to innovate the EWP denature process, first maltodextrin solution were put into egg white liquor, and then some low molecular sugar was removed by fermentation before drying and dry heating, so the brown reaction was reduced meanwhile the good effects of Maillard reaction were fully used. It concluded that this method can accelerate the speed of gel enhance, the M-EWP (Maillard-reacted EWP) could form a gel whose strength was 3300 g with a higher tolerance to pH. The gel form temperature of M-EWP was 67℃. The study of hydrophobicity, free sulfhydrxyl groups, molecular weight and secondary structure of the M-EWP and EWP indicated that the proteins were also partly denatured and polymerized during modification, and the increase of high molecular weight protein. It was conferred that the higher concentration of high molecular weight protein polymer cause Maillard-reacted DEW with higher gel strength than DH-EWP.