This section is from the book "Experimental Cookery From The Chemical And Physical Standpoint", by Belle Lowe. Also available from Amazon: Experimental cookery.
Ice cream may be held as well as frozen in mechanical refrigerators. When frozen in them the ice cream often does not have a good texture because it is not stirred sufficiently during the freezing process. Some units have been made that stir the mixture while it is freezing but they are not common. However, quite acceptable ices, sherbets, and even ice cream may be made by adding substances, such as egg white or whipped cream, that tend to delay crystal growth. Beaten egg white is best for ices and sherbets, because this product is more typical of an ice or sherbet texture than the product formed by adding rich whipped cream. A good time to add the beaten egg white to ices is just as the mixture starts to freeze, for the stirring at this time aids in the formation of more nuclei. Whipped cream may be added before or after the mixture is placed in the refrigerator tray, depending on the type of product to which it is added.
The published results of Isenberg and Baer, on the use of ice-cream improvers in commercial products, indicates that they would be of practically no benefit in home-made ice cream.
Home-Made Ices and Sherbets
Ices and sherbets have a lower freezing point than ice cream, for they usually contain a greater quantity of sugar. The use of gelatin and egg white in home-made ices seems to improve the texture in some instances, but in others to have little effect. When the hot sirup is poured over the beaten egg white the results obtained are as good as when the beaten egg white is added during the freezing process.