This section is from the book "Experimental Cookery From The Chemical And Physical Standpoint", by Belle Lowe. Also available from Amazon: Experimental cookery.
When the sugar is whipped into the whites, it may be added before whipping is started but this materially lengthens the time for whipping. The preferable time for adding the sugar is after the cream of tartar and salt are added. The sugar is added gradually for hand beaters and the whites beaten until stiff and shiny. The peaks stand up with slight rounding or bending of the tip ends.
The meringue method is particularly good to use with an electric beater, for the rapid revolutions can soon over-whip the whites to the dry stage. Adding the sugar during whipping of the whites increases the time for beating but also tends to prevent mechanical coagulation and tends to prevent leakage, thus stabilizing the foam.
In class work about nine times out of ten better results are obtained if all or at least half of the sugar is added to the egg white before any of the flour is added. Barmore reports the same result. Yet one person that the writer knows who makes excellent angel cakes always mixes all the sugar and flour together and then adds it to the egg white. It illustrates a point that constantly impresses all who have a chance to observe different people work with foods. There is no one method that always produces the best result. It seems best to give the method or methods successfully used by the majority.
However, adding about three-fourths of the sugar to the egg whites and sifting the remainder with the flour make the flour easier to incorporate. Hence, the flour can be added with less folding with the result that toughness is not increased from long folding and the volume of the foam is not materially reduced. Mixing the sugar and the flour before adding to the egg white has not produced as satisfactory results as folding the sugar first. As one student remarked, "The addition of the sugar to the egg white seems to prepare the egg for blending with the flour."
Flour. The flour is folded into the mixed sugar and egg white. Here the amount of mixing also affects the volume and tenderness of the cake. Too little mixing does not blend the flour sufficiently with the sugar and
Fig. 37. - Angel cake. Showing effect on the volume and texture of varying the folding of the sugar with the egg white. Cake flour used. Experiment (69,A). As shown in the illustration the cakes are about five-sixths actual size.
Fig. 37.
1. The sugar folded 20 strokes.
2. The sugar folded 40 strokes.
3. The sugar folded 60 strokes.
4. The sugar folded 80 strokes.
5. The sugar folded 120 strokes.
6. The sugar folded 180 strokes.
Fig. 38. - Angel cake. Showing effect of substituting bread flour for cake flour in Fig. 37. Experiment (69,E).
Fig. 38.
1. The sugar folded 20 strokes.
2. The sugar folded 40 strokes.
3. The sugar folded 60 strokes.
4. The sugar folded 80 strokes.
5. The sugar folded 120 strokes.
6. The sugar folded 180 strokes.
Fig. 39. - Angel cake. Showing effect on volume and texture of varying the extent of folding the flour with the sugar and egg white. Experiment (69,B). As shown in the illustration the cakes are about five-sixths actual size.
1. The flour folded 40 strokes.
2. The flour folded 60 strokes.
3. The flour folded 80 strokes.
Fig. 40. - Angel cake. Showing effect on the volume and texture of beating the egg white to different stages of stiffness. Experiment (69,C). As shown in the illustration the cakes are about five-sixths actual size.
1. Egg white slightly under-beaten.
2. Egg white beaten sufficiently.
3. Egg white slightly over-beaten.
Egg white mixture, and the grain is coarser. Spots of flour may occasionally be found. These are more likely to occur when the sugar has not been sufficiently mixed, or when all the flour is sifted over the cake at one time, or if too thick a layer is used, which increases the difficulty of incorporating the flour, as it tends to pile and roll up in balls. Longer mixing of the flour with sugar and egg white tends to produce a fine grain and small cells. See Fig. 39, cakes 2 and 3. The longer mixing of flour also has a tendency to toughen the cake, which may be due to development of the gluten of the flour and to the thicker cell walls caused by combining several cells through loss of air by mixing. An amount of mixing of the flour just to blend it well with the egg white and sugar usually produces the best results.
Texture. The texture and grain, also the volume and tenderness, of angel cake are influenced by several factors: (1) The mechanical treatment, which includes the kind of beater used, the degree of whipping of the whites, the method of and extent of mixing the ingredients; and (2) the ingredients used, their amount and kind.
The factor determining the size of the cells to the greatest degree is the type of beater used and the extent to which the egg white is beaten, which has been considered. Longer whipping produces more and smaller air bubbles so that the cells are smaller, the grain finer. Rotary and electric beaters, in general, give finer grain than whisks.
 
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