Experimental cookery

If too much water is added to the egg a point is reached at which the white becomes too tender and too many cells break when the air expands during cooking. Evidently the addition of water to egg white retards coagulation by beating, for a longer time is required to beat the white to a definite stage than when no 354 EGG COOKERY liquid is added. This retardation of coagulation may be due to the lessened concentration of the egg white. Kind o£ liquid in omelets. The liquid added to foamy omelets may be water, vegetable juice, tomato juice, or a mixture of one-third lemon juice and two-thirds water. If a tablespoon of milk is added to an egg white it will not form a foam. If added to the beaten white the volume is quickly reduced and the foam is destroyed. Dizmang and Sunderlin investigated the effect of milk on the whipping quality of egg white. Their results are given in Table 42, and indicate that the fat of the milk is responsible lor breaking the foam. But the size of the fat globules is also important, smaller particles having less effect. TABLE 42 The Efffxt of Milk on Whipping Quality of Egg Whites {Dizmang and Simderlin) Largest number of drops added to Substance added to one egg white, permitting formation egg white of foam stiff enough to stay in an inverted bowl Cream (20% fat) 1-2 Whole milk 2-3 Sterilized whole milk 8 Reconstituted powdered whole milk 50-70 Cream (20% fat) homogenized, 3000 lbs. . . 70 Evaporated milk 50-350 Separated milk 400-446 Whole milk, homogenized, 2500 lbs 400-450 Whole milk homogenized at 3000 lbs 1000 Reconstituted powdered separated milk. . . . 1600 The addition of 1 teaspoon of lemon juice and 2 teaspoons of water to an egg white brings the reaction to about />H 4.8, the isoelectric point of the egg albumin. It may be higher or lower, depending on the original ^H and perhaps the size of the egg. The addition of a tablespoon of tomato juice to an egg white does not lower the pH to 4.8. The addition of tomato juice and the lemon juice results in a more tender omelet, and one of greater volume, if the conditions of mixing have been standardized, if the liquid is added after the egg white is partially beaten, and if beaten to the same degree of stiffness. Tomato juice requires longer for whipping than the water, and the mixture of lemon juice and water requires still longer than the tomato juice. The addition of the acid tomato and of the lemon lessens the alkalinity of the egg white. Bogue has reported that the foam- ing properties of gelatin are greatest at the isoelectric point. If the foaming properties of egg white are also greater at the isoelectric point, a greater REVIEW OF LITERATURE ON ANGEL CAKE 355 volume might be expected at pH 4.8. This greater volume is usually obtained, with the addition of tomato or lemon juice, but a longer whipping time is required. Tomato and lemon both contain citric acid. The greater tenderness with the use of tomato juice and lemon juice probably results from a peptizing effect of the citrate ion on the egg protein. If lemon juice is merely added to egg white without whipping it, coagulation of the egg white is produced, but with beating the lemon juice is thoroughly mixed with the egg white. A better volume is usually obtained if the egg white is beaten until frothy before the lemon juice or tomato juice is added.