Emulsifed Semi-Solid Foods

Salad Dressing

Periods: Three

Period 1: Planning and familiarization with product evaluation methods

Period 2: Production

Period 3: Product evaluation

Objectives:

1. To familiarize the students with the principles and methods of manufacturing salad dressing.

2. To acquaint the students with the factors that influence finished product quality.

Background:

The term "Salad Dressings" generically covers a broad range of products that includes mayonnaise, salad dressing, and French dressing as defined by FDA Standards of Identity, and a large number of undefined products that include "slaw" dressing, Italian dressing, 1000 island dressing, creamy garlic dressing, etc. These dressings range from semi-solid (mayonnaise) to fluid products with very low viscosity. All salad dressings include in their formulation oil, an acidifying agent, and an emulsifying agent. The emulsifying agent, usually egg yolk solids (required in products covered by Standards of Identity), functions to form a coating around each oil globule to prevent coalescing. The emulsifying process must be carefully controlled in equipment specifically designed for this purpose to insure proper body characteristics. Other ingredients including starch pastes, gums, sugar, salt and spices may be added to impart desirable flavor and body characteristics. Careful formulation and use of high quality ingredients is essential since the product is subjected to many adverse conditions (light, air, metals, etc.) which cause deterioration during and after processing. For additional background information see

http://class.fst.ohio-state.edu/FST401/Process-Equip/salad%20dressing/SALAD%20DRESSING.html

Mayonnaise, the original salad dressing, has 75% oil, about 4% egg yolk, vinegar and mustard flour. Defined salad dressing, the first "low fat" dressing, has 40% fat and 2-4% starch paste in addition to the other ingredients of mayonnaise. Pourable dressings, which come in a wide range of compositions and flavors, have less oil than spoonable dressings and generally contain xanthan gum as a replacement for oil in Mayonnaise and starch in Salad Dressing.   Some typical formulations are tabulated below.

 

Ingredient

40% fat pourable dressing

30% fat pourable dressing

20% fat pourable dressing

Oil (%)

40

30

20

Water (%)

35.2

45.2

55.2

Vinegar (%)

8

10

10

Sugar (%)

10

10

10

Salt (%)

2

2

2

Xanthan gum (%)

0.3

0.3

0.3

Egg yolk solids (%)

4.5

4.5

4.5

Spices are added to taste depending on the type of dressing.

Procedure:

A. Formulation and Manufacturing

The characteristics of the salad dressing are markedly affected by formulation, order of additions of ingredients and the operation of the colloid mill.

For pourable dressing -

1. Add salt to the measured amount of water in the mixing bowl and mix until the salt dissolves

2. Add the sugar-xanthan gum mixture and agitate to prevent clumping. of the xanthan gum in the water. The mixing speed should be 150 r.p.m.

3. Add vinegar with mixing speed constant at 150 r.p.m.

4. Reduce the mixing speed to 90 r.p.m., and add the egg yolk solids, then increase the speed to 150 r.p.m. and continue mixing until a smooth creamy mixture is obtained (approximately 1-2 minutes).

5. Reduce the mixing speed to 120 r.p.m. and start addition of the oil at a constant rate. Increase the rate of oil addition with stepwise increases in mixing speed until 210 r.p.m. is reached. Continue mixing (at 210 r.p.m.) for 2 minutes after all the oil is added.

6. Emulsify by passing the mixture through the colloid mill

7. Fill into 100 ml graduated cylinders for layer separation analysis, and the remainder into furnished jars, cap and store all samples at 36° F for at least 48 hours before analysis.

 

Evaluation:

Describe your observations in respect to separation after 48 hours quiescent storage. Measure the depth of the emulsion layer in all samples that show separation. How many layers are visible?

Determine the pH (non-oil phase) of each sample.

Determine the viscosity immediately after making and at the time of sensory evaluation.

Cling or adhesion to lettuce is an important attribute of salad dressings. Develop your own test for cling.

Evaluate for sensory properties. Commercial samples will be available for inspection.

 

 

References:

Hardwick G B & Kennedy, R. L. 1982. Apetizers, dressings and salads CBI Publ. Co. Boston MA

Mitchell, P. 1995. The Complete Book of Dressings. Mac Millan, NY (Only available in PAR Stacks