Food Science exam 1

Question 1

pH that defines low vs high acid

Answer 1

4.6

Question 2

3 types of water

Answer 2

Free, absorbed and bound

Question 3

Associated in layers by hydrogen bonds, typically around hydrophilic molecules

Answer 3

Absorbed water (structural)

Question 4

Chemically bound, water of hydration, water ion

Answer 4

Bound water

Question 5

ratio of vapor pressure of food divided by vapor pressure of pure water at same temp

Answer 5

Water activity (Pure water=1)

Question 6

Water flows from ___ to ___ water activity

Answer 6

high to low

Question 7

How to prevent water migration aka lower water activity?

Answer 7

salting, freezing, drying, sugar coat (raisins)

Question 8

Water activity less than ____ equals a shelf stable food

Answer 8

0.6

Question 9

Microorganisms are most active around ph of __

Answer 9

7

Question 10

Organic acids?

Answer 10

Malic, tartic, citric, fumanic, lactic, acetic

Question 11

Glucose and galactose are aldose or ketose sugars?

Answer 11

Aldose (CHO)

Question 12

Fructose is a aldose or ketose sugar?

Answer 12

ketose (C=O)

Question 13

Disaccharides are joined with a ___ bond

Answer 13

glycosidic

Question 14

Sucrose is made from ___ and ___ with a ___ bond

Answer 14

glucose and fructose, alpha 1,2

Question 15

Lactose is made from ___ and ___ with a ___ bond

Answer 15

glucose and galactose, beta 1,4

Question 16

Maltose is made from ___ and ___ with a ___ bond

Answer 16

glucose and glucose, alpha 1,4

Question 17

____ is the only non reducing sugar

Answer 17

Sucrose

Question 18

Reducing sugars have a free

Answer 18

aldehyde or ketone group

Question 19

The sweetest sugar is

Answer 19

fructose

Question 20

invert sugar is

Answer 20

sucrose and h2O converted to glucose and fructose by enzyme invertase, less likely to crystallize than sucrose

Question 21

Three browning reactions

Answer 21

Enzymatic, caramelization, and malliard browning

Question 22

Caramelization and malliard are enzymatic or non enzymatic?

Answer 22

Non

Question 23

Reaction bt oxygen and phenolic compounds

Answer 23

Enzymatic browning (browning in bananas and avocado)

Question 24

Enzymatic browning can be prevented by:

Answer 24

remove oxygen 
add vitamin C 
heating 
decrease pH 
adding sulfites

Question 25

The thermal decomposition of carbohydrates

Answer 25

Caramelization

Question 26

The reaction between a reducing sugar and an amino group

Answer 26

Malliard browning

Question 27

Malliard browning can be controlled by

Answer 27

control temp decrease pH reduce water activity

Question 28

Homogenous- a solute dissolved in a solvent

Answer 28

Solution

Question 29

Heterogenous and unstable

Answer 29

Suspension

Question 30

Heterogenous and stable, consists of dispersed phase and continuous phase

Answer 30

Colloidal dispersion

Question 31

Starch is composed of

Answer 31

amylose and amylopectin

Question 32

Amylose structure

Answer 32

linear chain with alpha 1,4 bonds

Question 33

Amylopectin structure

Answer 33

branched chain w alpha 1,6 bonds

Question 34

A food higher in ____ (amylose/amylopectin) will absorb more water

Answer 34

amylopectin

Question 35

What is corn syrup

Answer 35

Starch treated with enzymes to make maltose and glucose mixture

Question 36

What is high fructose corn syrup

Answer 36

Glucose isomerase converts glucose to glucose and fructose

Question 37

Cellulose structure

Answer 37

Linear with Beta 1,4 bonds, cant digest

Question 38

Types of gums

Answer 38

Agar, xantham, pectins, guar, carob/lust, tara

Question 39

If you increase mixing (shear) then particles

Answer 39

either line up in the direction of the force or particles clump to a force

Question 40

What is PKU?

Answer 40

recessive genetic disorder where people cant convert phenylalanine. (aspartame contains phenylalanine)

Question 41

Flavor that is imparted by glutamate and ribonucleotides

Answer 41

Umani

Question 42

MSG is

Answer 42

a sodium salt of glutamic acid

Question 43

Protein denaturation is

Answer 43

any modification of structure that doesnt break peptide bonds

Question 44

Proteins can be denatured by

Answer 44

acid heat mechanical force

Question 45

Clumping of denatured proteins which results in thickening or hardening

Answer 45

Protein coagulation

Question 46

Protein coagulation is caused by

Answer 46

``` Heat enzymes mechanical acid salt ```

Question 47

Milk coagulation is caused by

Answer 47

Chymosin, lower acidity

Question 48

Dispersed and continuous phases in a sol

Answer 48

solid, liquid

Question 49

Dispersed and continuous phases in a gel

Answer 49

liquid, solid

Question 50

Dispersed and continuous phases in a emulsion

Answer 50

liquid, liquid

Question 51

Dispersed and continuous phases in a solid foam

Answer 51

gas, solid

Question 52

Dispersed and continuous phases in a foam

Answer 52

gas, liquid

Question 53

What proteins make up gluten and which is responsible for viscosity or elasticity

Answer 53

Gliadin-viscosity | Glutenin- elasticity

Question 54

High gluten results in

Answer 54

tough and chewy like pizza dough

Question 55

Celiac disease is

Answer 55

gluten sensitivity (gliadin antibodies)

Question 56

Less than ____ ppm equals gluten free

Answer 56

20

Question 57

What makes you cry when you cut an onion?

Answer 57

Compartmentalization- when you cut it releases a lachrymatory agent

Question 58

Added to food to inhibit enzymatic action

Answer 58

sulfites

Question 59

Trypsin inhibitors do what

Answer 59

prevent protein digestion

Question 60

What enzyme is used in fruit juice processing

Answer 60

Pectinase- breaks down cell wall

Question 61

A carboxylic acid with a hydrocarbon chain attached

Answer 61

Fatty acid- amphipathic

Question 62

Triglyceride is

Answer 62

3 fatty acids bound to glycerol

Question 63

Phospholipid is

Answer 63

glycerol with 2 FAs and phosphate group attached

Question 64

Sterols in plants vs animals

Answer 64

phytosterols vs cholesterol

Question 65

Fat soluble vitamins are

Answer 65

lipids

Question 66

Fats have a melting

Answer 66

range bc of mixed composition

Question 67

Melting range of fats is affected by

Answer 67

fatty acid composition FA chain length degree of saturation configuration of double bonds

Question 68

What is a conjugated fatty acid

Answer 68

FA with 2 or more double bonds separated by a single bond (inhibit carcinogens and promote weight loss)

Question 69

Omega 3 FAs

Answer 69

EPA and DHA

Question 70

TAG composition

Answer 70

Can detect if fats have been altered based on triglyceride composition

Question 71

Oxidative rancidity is the result of

Answer 71

uptake of oxygen and formation of peroxides, hydroperoxides

Question 72

How to control oxidative rancidity

Answer 72

Control amount of unsaturated FAs, oxygen conc., limit UV light, control temp, remove sources of metal catalysts, addition of antioxidants

Question 73

What antioxidants can be added to food

Answer 73

Vita E, citric acid, BHA, BHT, EDTA, phosphates, rosemary

Question 74

What is hydrolytic rancidity?

Answer 74

hydrolysis of triglycerides to free fatty acids and glycerol (often catalyzed by lipases)used for some cheese

Question 75

What kind of molecule is a good emulsifier

Answer 75

Amphiphiles (egg yolk in mayo)

Question 76

What is brominated vegetable oil?

Answer 76

Used to stabilize citrus and fruit flavored drinks (gatorade, mtn dew), prevents seperation of less dense flavoring agents