Experimental cookery

Effect of temperature upon whipping of eggs. Since a low sur- face tension is one essential for the formation of a foam, it follows that a lowering of the surface tension will aid its formation. Eggs that are taken from the refrigerator and beaten while still cold do not whip up as readily or quickly as those at room temperature. Surface tension is lowered with increased temperature so that it is probably one factor in bringing about this result. The Bakery Research Department of Procter & Gamble Company have reported that "regardless of the length of time of beating, a given sugar and egg mixture, when whipped at 60°F., will never become as light as will a mixture of the same proportions beaten at the same speed and at a temperature of 110°F." St. John and Flor found that a greater volume was obtained at room temperature, about 21 °C., than at refrigerator temperature, 13°C. A still better volume was obtained at 30°C., but they report that while drying EGG BEATERS 349 the whites to measure the volume the liquid part from those beaten at the highest temperature separated more readily. Season and age of eggs and whipping. The whipping quality of eggs varies, according to the season in which they are produced. Nemetz has reported experiments in w^hich whole eggs that had been broken and frozen in April, July, and September were used. The eggs were used in sponge cake and cream puffs. With all mixing and baking conditions stand- ardized, the April eggs gave a 15 per cent increase and the September ones a 10 per cent increase in volume over the July eggs in sponge cake. Similar results were obtained in cream puffs. Burke and Niles found that egg whites from eggs produced during the season when eggs are considered less desirable beat to a stiffer foam when beaten the same length of time than the whites from eggs produced early in the spring. Nemetz states that if fresh or frozen eggs are used in a similar mix under identical conditions, greater volume and greater yield will be obtained from frozen eggs. Bakers also claim that egg whites do not whip as well if used the next week after being frozen as when they have been frozen at least three months. Barmore states that the older the eggs, when whites were beaten for equal lengths of time, i.e., 1, 2, and 3 minutes, the less stable the foam. However, when eggs were beaten 4 minutes the stability was practically the same for all ages of egg used, e.g., fresh, 3, 6, and 9 days. Egg beaters. Egg whisks or whips are made with wires of varying thickness. The thick wire does not whip or divide the egg white as easily as the finer wire. The air cells are larger than when a whisk with finer wires is used, though the size of the enclosed air bubbles decreases with longer beating with any type of beater. Whisks with thicker wires may require two to four times as many strokes to beat an egg white to a definite stiffness as one with finer wires. Some egg whisks beat the egg quickly, dividing it into many very fine cells without giving an excess of the curdy- looking precipitate within the whipped white. Some produce a greater curdled appearance than others, even when the egg does not appear to be beaten to the same stage of stiffness.