The presence of heat-stable conformers of ovalbumin affects properties of thermally formed aggregates.
The aim of this work was to study the effect of the formation of more heat-stable conformers of chicken egg ovalbumin during incubation at basic pH (9.9) and elevated temperature (55 degrees C) on the protein aggregation properties at neutral pH. Native ovalbumin (N-OVA) is converted on the hours time-scale into more heat-stable forms denoted I- (intermediate) and S-OVA, that have denaturation temperatures 4.8 and 8.4 degrees C, respectively, higher than that of N-OVA. The conversions most likely proceed via I-OVA, but direct conversion of N-OVA into S-OVA with slower kinetics can not be excluded. It is demonstrated that both I- and S-OVA have similar denaturation characteristics to N-OVA, except that higher temperatures are required for denaturation. The presence of even small contributions of I-OVA does, however, reduce the Stokes radius of the aggregates formed upon heat treatment of the material at 90 degrees C about 2-fold. This affects the gel network formation considerably. Since many (commercial) preparations of ovalbumin contain varying contributions of the more heat-stable forms mentioned, proper characterization or standardization of the isolation procedure of the material is essential to control or predict the industrial application of this protein.
de Groot
Jolan
J
Wageningen Centre for Food Sciences, Diedenweg 20, 6700 AN Wageningen, The Netherland.
de Jongh
Harmen H J
HH
D000818:Animals; D002152:Calorimetry, Differential Scanning; D002645:Chickens; D006358:Hot Temperature; D007700:Kinetics; D010047:Ovalbumin / Q000737:chemistry* / Q000378:metabolism; D011487:Protein Conformation; D013997:Time Factors
D010047:Ovalbumin