A stable emulsion must contain an emulsifier to keep one liquid dispersed in the other. The emulsifier:
a. is dissolved in the water
b. is dissolved in the oil
c. adsorbs at the oil-water interface and surrounds the emulsion droplets
d. forms a stable film around the droplets to prevent them from separating
e. c and d
2. What molecular characteristics (types of molecular groups) must an emulsifier have in order to function as an emulsifier? Why is this necessary? (In other words, think about where the emulsifier is located and what it does. What type of molecular characteristics make that possible? (Ionic? Polar? Hydrophobic? Hydrophilic? A combination?)
3. According to the text book (page 468), higher frying temperatures (375-390F) are required for smaller pieces of food, whereas larger pieces of food require lower frying temperatures (350-365F). Explain why this is the case.
4. Define the smoke point of a fat. What chemical compound is formed when the fat reaches its smoke point? How is this formed? (What compound breaks down to form this?)
5. In the previous question, why do the fats you chose have the highest and the lowest smoke points respectively? In other words, what characteristics of a fat cause it to have a high smoke point? What characteristics cause it to have a low smoke point?
List two fats or oils (NOT foods) that are mainly saturated, two fats or oils (NOT foods) that are mainly monounsaturated, and two fats or oils (not foods) that are mainly polyunsaturated.
7. Define the term “gel”.What happens to a gelatin gel when it is heated?
8. Why canâ€™t raw pineapple or raw kiwi be used in the preparation of a gelatin salad?
9. Why can canned pineapples be used to make a gelatin gel, whereas fresh pineapples cannot?
10.What effect does the addition of canned fruit pieces have on a gelatin gel and why? How can you counteract this?
11. DefineSyneresis. When is syneresis likely to occur in a gelatin gel, and why?