2012 Volume 45 Issue 2 Pages 123-132
The objective of this study was to investigate the involvement of egg yolk in the structure formation of “creamy custard pudding”, which was comprised of upper and lower parts differing in appearance and texture.
In pudding prepared with 100 g of milk, 100 g of milk fat cream, 20 g of sugar, and 40 g of egg yolk, the fat content was significantly higher in the upper than in the lower part, but no significant difference was noted in the fatty acid composition between the two parts. The cholesterol and phospholipid contents were slightly higher in the upper and lower parts, respectively. The median particle size in the upper part was greater than that in the lower part, and the hysteresis area and non-Newtonian viscosity were significantly greater in the upper than in the lower part. These differences in the lipid content, median particle size, and static viscoelasticity between the upper and lower parts present in this pudding were not observed in puddings heated for a shorter time, with a small quantity of blended egg yolk, compounded with egg white, or high quantity of blended milk fat cream. Dynamic viscoelasticity measurement clarified that egg yolk, rather than egg white, contributed to the structural stability of “creamy custard pudding”, and increases in the milk fat cream content and the heating process enhanced the structural stability. In addition, G′ was higher than G″ in all measured frequency regions in both the upper and lower parts, this pudding was characterized as a “weak gel”, in which both G′ and G″ were found to be dependent on frequency. Additionally, the “weak gel” rheological property was more marked in the lower part.
