Q. Determine the best method of preparing a stable emulsion?
To determine the best method of preparing a stable emulsion like mayonnaise.
• learn the process of preparation of a stable emulsion, and
• discuss the various factors affecting the formation of a stable emulsion.
Mayonnaise is an emulsified salad dressing, which requires ingredients in certain proportions to be mixed together to form a stable oil-in-liquid emulsion. The egg forming about 20% of the total weight provides the emulsifying agent lecithin, present in the yolk. This helps in stabilizing the other ingredients in the mixture. While whole egg may be used in the preparation of the product, it is the yolks, which have better stabilizing ability as they hold moisture in dispersion. Therefore the ratio of other ingredients such as salt, vinegar and spices should not exceed 65:10:5 percent of the weight of the egg contents, since the yolks have limited assimilating power. Continuous beating breaks up the oil into fine globules, which get simultaneously dispersed in liquid to convert it into a semisolid stable product.
Rotary beater or whisk, blender, bowl, standard cups and spoons
Eggs, 1 cup refined oil, 1tablespoon vinegar, ½ teaspoon salt, ½ teaspoon sugar, ½ teaspoon mustard powder.
The activity is divided into three sections A, B and C to study the effect of variations on the end result and determine the most suitable method of preparing mayonnaise for different applications. So carry out the activity following the steps indicated herewith:
A) Method of preparing mayonnaise
i) Separate yolks from the eggs and drop into small bowl.
ii) Add all the ingredients except vinegar and oil to the yolks.
iii) Beat with a whisk or beater till ingredients are well blended.
iv) Add the oil drop by drop alternating it with the vinegar while continuously beating the mixture. Continue beating till the mixture
begins to thicken.
v) Continue the process, gradually increasing the quantity of oil added at one time, till all the ingredients have been used up and the resultant product is spoonable into a jar.
vi) Observe samples for microscopic structure, colour, consistency, taste, flavour and applicability.
B) Effect of varying the method of combining ingredients
i) Add seasonings and vinegar to the yolks and then start the whisking. Add oil as in ‘A' (iv - v) and when ready, keep sample aside for assessment.
ii) Beat the egg yolks first and then add the oil drop by drop till thickened, followed by spices and vinegar. Set the sample aside.
iii) To the yolk, add seasoning, 1/3 vinegar and then oil drop by drop beating till thickened, followed by 1/3 vinegar again and then the rest of the oil and the remaining 1/3 vinegar to complete the product. Keep sample aside.
For quick and even continuous beating, an electrical blender may be used and the ingredients continuously added without much pause following the method in A(i-vi).