Laboratory Exercise: Pretzels

Purpose

The purpose of this laboratory is to produce a food product and to become aware of the many instances where an understanding of chemistry is important in its manufacture. The product chosen is pretzels and the main variables we will examine are the color and texture of the pretzel's surface.

Pretzel Recipe

• 1 bottle beer
• 1 quart milk
• 2 packages yeast
• 4 tbs melted shortening
• 6 lb. of flour
• 2 tbs salt

Mix the ingredients, proof the dough (let sit) for 30 minutes, and then punch down. At this point each group will form twelve pretzels. Once formed, dip the pretzels in one of the following solutions that have been heated to near boiling (except for the egg):

• 2% citric acid
• 2% NaOH
• 2% whey
• 2% Na₂CO₃
• Water
• Egg White

Place the pretzels in the heated oven ( 400°F) for 15 minutes or until done. Each group should obtain 2 pretzels from each other group and retain some of their pretzels. All pretzels should be compared and evaluated for:

• General Appearance
• Color
• Texture
• Crust Formation
• Flavor

Rank all pretzels for each characteristic and determine which is the most acceptable product. The instructor will hand out data compiled by the entire class. Determine if the differences noted by the class are significant. Determine the L value for the pretzels in your Group using the Hunter Colorimeter. Also determine the LAB value. Determine the force to break the surface of a pretzel using the texture analyzer. Give a copy of your values obtained with the Hunter and the texture analyzer to the instructor for distribution to those in other groups.

Questions

1. What is the function of each of the following ingredients in the pretzel formulation?
   • Flour
   • Beer
   • Milk
   • Salt
   • Shortening
2. How did each dip affect the surface of the pretzels? Postulate a mechanism for the observed effect.
3. What caused the browning of the pretzel crust? How can variations due to dips be explained?
4. Why was the yeast included in this product? What did the yeast produce? What did they consume? What components affected the retention of yeast by-products?
5. If we had been making bread instead of pretzels, the milk would have been given a heat treatment. Why? Why wasn't this necessary with the pretzels?
6. Compare your visual color scores to those obtained with the hunter. How well do they compare?
7. Compare the values you gave for texture and crust formation to those obtained with the texture analyzer. Which of the objective values agrees best with the instrumental value?