FoodNet

Experimental cookery

1932

Page 222

Presented as published in 1932. Historical recipes may not meet modern food-safety standards. Cook from the modern interpretation, not the original instructions.
Stamm has reported that the method of preparation affects the size of the particles of the dispersed phase. Harkins (1928) states that the "method used in preparing an emulsion is one of the factors determining the dis- tribution, but the most striking feature of the present work is that the shift of the number maximum is so slight with the different methods of stirring employed." By number maximum Harkins refers to the number of particles of the dispersed phase in a definite volume. Thus the ap- paratus, its speed, and the time used in mixing emulsions like mayonnaise, may or may not determine to a great extent the size of the particles formed and the stability of the emulsion. Intermittent mixing for emulsions. Clayton states that what may be termed the mechanics of emulsification are far from being understood even now. In some experiments in making different emulsions, investiga- DOES PEPTIZATION PLAY ROLE IN EMULSIFICATION? 275 tors have reported that intermittent shaking is more effective than con- tinuous shaking or agitation. Clayton believes that shaking is an inferior method of making emulsions, but that continuous shaking should give equally as good results as the intermittent shaking, provided the emulsified portions are continuously removed from the mass. Intermittent agitation is explained as being more effective than continuous agitation, because of the rest periods, w^hich allow time for adsorption of the emulsifying agent. In making mayonnaise, the beating is often intermittent, for in stopping to add oil to the mixture, short rest periods occur. Foams and formation of emulsions. Harkins in commenting on the method of preparation of emulsions, states that in a number of cases the emulsion failed to form after stirring rapidly with a motor-driven egg beater for 5 minutes, which was not in accord with the usual emulsifica- tion in a few seconds. He found that in all these cases no foam was pro- duced, and that as sooxi as a foam formed, emulsification occurred in a few seconds. This may be a factor in the formation of some emulsions in food preparation. MAYONNAISE Definition by Food and Drug Administration. "Mayonnaise, may- onnaise dressing, mayonnaise salad dressing, is the semi-solid emulsion of edible vegetable oil, egg yolk, or whole egg, a vinegar, and/or lemon juice, with one or more of the following: salt, other seasoning commonly used in its preparation, sugar and/or dextrose. The finished product contains not less than 50 per cent of edible vegetable oil." Does peptization play a role in emulsification? In no theory of emulsification that the writer has read is peptization mentioned. Yet the following comments by Bancroft on peptization so vividly describe what happens in making mayonnaise that they are given. Bancroft, in his chap- ter, ''Preparation of Colloidal Solutions," states that the methods of making colloidal solutions may be grouped under two heads, the dispersion and the condensation methods.