Midterm T.2

Question 1

Functions of proteins in foods

Answer 1

emulsifiers / foaming agents: amphiphilic properties, thickening agents, gelling agents, flavour generation

colour: through Maillard reaction (reducing sugar and amino acids react with dry heat)

Question 2

When do proteins precipitate

Answer 2

at their isoelectric point: the pH at which there is no net charge on the protein

Question 3

Most food lipids are

Answer 3

triglycerides

Question 4

What determines fat properties

Answer 4

structure of fatty acids esterified to glycerol

Question 5

Function of lipids in foods

Answer 5

nutrient (essential fatty acids, caloric density, satiety)

carry flavours and fat-soluble vitamins (A, D, E, K)

enhanced heat transfer medium (frying)

Question 6

Deterioration of Fats can cause:

Answer 6

hydrolytic rancidity: free fatty acids are liberated when fat and water interact, ffa are volatile

oxidative rancidity: biochemical reaction between fats and oxygen in which long chain fatty acids are degraded, shorter chain fatty acids are released which are “odorous”

antioxidants used to prevent oxidation

Question 7

Reasons to reduce water

Answer 7

inhibit microbial growth

prevent chemical reactions

Question 8

Function of water

Answer 8

vitamins and minerals may be dissolved in water

lubrication for mastication and swallowing

influence texture

facilitates heat transfer

facilitates microbial growth (spoilage, pathogenic microbes, desired food fermentation microbes)

facilitates freeze concentration (water moves out of food to produce large crystals, reduce food quality)

Question 9

What do macrominerals do?

Answer 9

assist in the body’s chemical reactions

help form body structures

important for energy transfer

macro: sodium, calcium, magnesium, phosphorous

trace minerals: iron, zinc, iodine

Question 10

What changes during food processing

Answer 10

water is lost

macronutrients are preserved

micronutrients (vitamins and mineral) contents are altered