Midterm 1

Question 1

What is a Difference/Discrimination Test?

Answer 1

objective measurement of differences of tastes between similar product types

Question 2

What are the two sensory tests?

Answer 2

Difference/discrimination test and descriptive test

Question 3

What is a Descriptive Test?

Answer 3

verbal description of characteristics of products

Question 4

What is an example of Consumer Testing?

Answer 4

Affective Test

Question 5

What is an Affective Test?

Answer 5

measurement of a subjective impression or preference for products

Question 6

Three international food regulatory agencies

Answer 6

FAO, WHO, JECFA

Question 7

Two theories that are used to describe the chemical basis of sweetness

Answer 7

AH,B, X Theory and the Multi-Point Attachment Theory

Question 8

AH-B Theory of Sweetness

Answer 8

Proposed that a sweet-tasting compound must contain a hydrogen bond donor (AH), as well as a hydrogen bond acceptor (B)

Question 9

Multi-point Attachment Theory

Answer 9

Assumes the presence of at least 8 fundamental recognition sites between a sweetener and a sweetness reception site

Question 10

Which flavours involve the use of ion channels?

Answer 10

Salty and sour tastes are detected through ion channels which regulate the flow of ions across the membrane where the movement generates a voltage

Question 11

Which flavours are detected by the G protein-coupled receptors?

Answer 11

Sweet, bitter, and umami

Question 12

How does the degree of dissociation of a food acid impact sourness?

Answer 12

Most acids in foods are weak acids. By increasing [H+], pH decreases, and the decrease in pH makes the food more sour. Any pH below 4.76 will keep the acid in pronated form and the product sour

Question 13

How do flavour enhancers work?

Answer 13

Synergism occurs when a flavouring stimulus attaches to the tongue receptors in combination with an or all of the following: MSG, IMP, or GMP. Different combinations provide stronger flavour signals to the brain. Bind with MSG has strongest flavour

Question 14

Which pigments are important for the colour of meat?

Answer 14

Myoglobin, a protein complex made of blobulin and iron. The colour of meat is influenced by the oxidation state of iron in the myoglobin molecule. A bright pink colour is preferred

Question 15

Colour of the reduced form of myoglobin?

Answer 15

Purple colour

Question 16

Colour of the oxygenated form of myoglobin?

Answer 16

Bright red

Question 17

Colour of the oxidized form of myoglobin?

Answer 17

Brown

Question 18

How do emulsifying salts improve the texture of processed cheese?

Answer 18

Emulsifyings salts are added and Na ions from emulsifying salts and Ca ions from caseinate are exchanged, product is heated and becomes hydrophobic. Insoluble casein becomes unbound and emulsifies fat globules in cheese through hydrophobic reactions to create smooth texture

Question 19

What is the chemical process of fermentation?

Answer 19

Undergoes aerobic respiration, where glucose is broken down to pyruvate (glycolysis - anaerobic process), and in the presence of oxygen, pyruvate moves into the mitochondria and takes part in Kreb’s Cycle and ETC. When oxygen is not present fermentation takes place

Question 20

What is lactic acid fermentation?

Answer 20

Glucose –> ATP + lactic acid

Question 21

lactic acid fermentation: yogurt example

Answer 21

1. start of fermentation, ST is more active
2. increased formic acid initiates growth of LAB by decreasing pH

Question 22

What is alcohol fermentation?

Answer 22

Glucose –> ATP + alcohol + CO2

Question 23

alcohol fermentation: beer foam

Answer 23

CO2 bubble stays stabilized due to Lipid Transfer Protein which is hydrophobic. It coats the CO2 bubble and binds with bitter iso-alpha acids to increase stability of foam