A mixture of egg yolks and hot water was beaten with a “Mixmaster of Sunbeam”. Other substances were added into the mixture in some experiments. Effects of the consistency of egg yolk, the temperature of water and added substances on the formation and stability of the egg yolk foam were studied. The effect of the egg yolk foam on the sponge cake was also studied. The following results were obtained.
1. When much water is added to egg yolks, more foam is made, but the stability of foam decreases.
2. When the temperature of water added to egg yolks is high, the formation of foam is accelerated, and its stability increases.
3. One per cent of tartaric acid in the mixture of egg yolks and water retards the formation of foam, but none of oil, sugar and salt of 1% does not affect it.
4. When the more sugar is added, the less foam is formed, but the stability increases.
5. When whipped egg whites are mixed in batter together with beaten yolks, soft texture of sponge cake is obtained.