Lecture 2: Food Chemistry

Question 1

What is a Proxumate Analysis of food?

Answer 1

The chemical constituents in food.

Question 2

True or False:

Food Products are mostly made up from biological origin.

Answer 2

True.

Question 3

What is food?

Answer 3

Food is a chemical mixture of carbohydrates, protiens, water, fats and miscellanenous atoms

Question 4

What are the some of the most common elements found in food?

Answer 4

C
H
N
O

Question 5

What are the five major categories of distinctly different chemical compounds described in food composition (Proximate composition)

Answer 5

• lipids
• Carbohydrates
• Proteins
• Water
• Minerals/Ash

Question 6

What is the unit used to express Proximate composition.

Answer 6

% of whole.

Question 7

What is important about Proximate composition?

Answer 7

• It helps us know the storage or shelf life if a food item
• conform to legal definitions of foods
• Directs processing parameters
• Determine energy value of foods
  (Caloric content)

Question 8

Why do use a “dry-weight basis”

Answer 8

This is due to the fact that water has no nutritional value, they take it out to only look at the primary components.

Question 9

Once you take out the mostuire, what will happen to the weight of the rest of the percentages?

Answer 9

They will increase.

Question 10

What are Carbohydrates?

Answer 10

Hydrates of Carbon

Acting as the main energy source of energy for animals and humans.

Question 11

How do you classify Carbohydrates?

Answer 11

Classified according to the number and type of molecules contained

Question 12

What are Monosacchrides?

Answer 12

Pentoses (5C) and Hexoses (6C)

• Glucose, Fructose, Glactose.

Question 13

What are Disaccharides?

Answer 13

Two monosaccharides linked

• Sucrose
• Lactose
• Maltose

Question 14

What are the two components of Sucrose?

Answer 14

Glucose + Fructose

Question 15

What are the two components of lactose?

Answer 15

Glucose + Galactose

Question 16

What are the two components of Maltose?

Answer 16

Glucose + Glucose

Question 17

What is the function of Sugar in foods?

Answer 17

• Provides Sweetness & enhances flavor
• Crystallization leads to characteristic products
• provides body and mouth feel (Viscosity)
• Attracts and holds water (Hygroscopic)
• Preservation effect at high levels

Question 18

What is the process of Caramelization?

Answer 18

Sugar decomposition at high temperatures creates brown polymers

Question 19

What is the Maillard reaction?

Answer 19

Reducing sugar & A.A react with heat.

Creates brown pigment Polymers.

Question 20

What are Oligosaccharides?

Answer 20

A combination of more than two disaccharides

Question 21

What are Polysaccharides?

Answer 21

A large chain of oligosaccharides such as starch, cellulose, pectin, some hydrocolloids.

Question 22

What are the 6 main reasons why you would add complex carboydrates are added to food?

Answer 22

• Increase dietary fiber content (nutrition)
• Thickens food
• form gels
• Bind water
• Stabilize proteins
• Serve as Prebiotics

Question 23

What is Starch?

Answer 23

A polysaccharide with Long chains of glucose units linked together (500 to >100,000)

Question 24

What is Amylose?

Answer 24

A Starch with linear chains (Gel formation)

Question 25

What is Amylopectin?

Answer 25

A Starch with branched chains (viscosity)

Question 26

True or false: | Starch is involved in Gelatinization and retrigradation

Answer 26

True

Question 27

What is Cellulose?

Answer 27

- Major Component of plant cell walls - It is a Polysaccharide - Long chains of Glucose molecules linked together with 1-4 linkages

Question 28

What is Pectin?

Answer 28

- Functions as an intercellular cement and provides texture o fruits and tubers.

Question 29

What are Gums?

Answer 29

Agar

Question 30

True or false: - Carbohydrates cannot be digested by humans, and are only used as dietary fibers

Answer 30

True.

Question 31

What is high fructose Corn Syrup?

Answer 31

Derived from corn starch - Varies fructose contents are used by the food industry (soft drinks, pasta sause)

Question 32

What is another name for High Fructose Corn Syrup?

Answer 32

Glucose-Fructose

Question 33

What are the Building blocks of Proteins?

Answer 33

Amino Acids

Question 34

How many Amino Acids are there?

Answer 34

There are 20 different ones.

Question 35

What is it called when you break down proteins?

Answer 35

Hydrolyzation

Question 36

What are the major things that change the properties of Proteins in foods

Answer 36

- pH - Heat Just small changes in there two things can cause MAJOR and dramatic changes in the protein molecules.

Question 37

What are the four types of structures in proteins?

Answer 37

- Primary - Secondary - Tertiary - Quaternary

Question 38

What are the functions of proteins in food?

Answer 38

- Emulsifiers and foaming agents: Amphiphilic properties (polar and non-polar)

Question 39

What is a Protein Emulsifier?

Answer 39

Egg yolk protiens & casein in milk

Question 40

What is a protien foaming agents?

Answer 40

Egg whites

Question 41

What is the function of Texture with proteins in food?

Answer 41

- thickening agents - binding agents - gelling agents

Question 42

What is the flavor additive of proteins?

Answer 42

- Specific amino acids can contribute to food flavor.

Question 43

What is the isoelectric point?

Answer 43

The pH at which there is not net change on proteins

Question 44

What happens to proteins when they are isoelectric point?

Answer 44

Proteins percipiate at their isoelectric point.