Carbohydrates

Question 1

__________ is the most common hexose found in foods and the major sugar in the blood

Answer 1

Glucose

Question 2

A derivative of __________, galacturonic acid, is a component of pectin, which is very important in the ripening of fruits and the gelling of jams

Answer 2

Galactose

Question 3

TRUE or FALSE?

Saccharide nomenclature uses D or L to describe the chemical spatial arrangement of certain saccharides

Answer 3

TRUE

Question 4

__________ also called fruit sugar and levulose, if found primary in fruits and honey

Answer 4

Fructose

Question 5

Sucrose is commonly known as __________ sugar, and consists of one glucose molecule and one fructose molecule linked together

Answer 5

Table

Question 6

A glucose molecule bound to a galactose molecule forms __________, one of the few saccharides derived from an animal source

Answer 6

Lactose

Question 7

The majority of starchy foods in their natural state usually contain a mixture of about 70-85% amylopectin and 15-30% __________

Answer 7

Amylose

Question 8

In foods, heat, enzymes and __________ are used to break starches down into smaller fragments called dextrins

Answer 8

Acid

Question 9

Why do starches from different plant sources differ in their ability to gel?

Answer 9

Because of the differences in concentration of amylose and amylopectin in various plant sources

• Corn starch: high amylose (forms gel)
• Potato starch: high amylopectin (no/poor gel)

Question 10

Pectic substances are found between and within the cell walls of fruits and vegetables include protopectin, pectin and __________

Answer 10

Pectic acid

Question 11

TRUE or False?
Gums are used in many frozen products because they control crystal growth, yield optimal texture, and make the food more stable in the freezing and thawing process

Answer 11

TRUE

Question 12

Starches that have been changed structurally by chemical or mechanical means are called __________ starches

Answer 12

Modified

Question 13

What are the effects of salt and sugar on starch gelatinization?

Answer 13

They compete for water and interfere with the gelling ability of the starch

Question 14

How are retrogradation and syneresis related?

Answer 14

Syneresis is the term used for water leaking from the gel and is the result of retrogradation

Question 15

List the following sugars in order of decreasing sweetness. (1 = sweetest, 5 = least sweet)

Glucose, Maltose, Lactose , Fructose, Sucrose

Answer 15

1) Fructose
2) Sucrose
3) Glucose
4) Maltose
5) Lactose

Question 16

What are the effects (increase or decrease) of sugars on: 
Water activity 
Microorganisms 
Chemical reactions 
Stability

Answer 16

Water activity: DECREASES
Microorganisms: DECREASE
Chemical reactions: DECREASE
Stability: INCREASES

Question 17

What are the by-products of sugar fermentation in the following cases?
Bread-making
Pickles/sausages
Wine/Beer

Answer 17

Bread-making: CO2
Pickles/sausage: Acid
Wine/Beer: Alcohol

Question 18

Direct heating of sugar is called __________

Answer 18

Caramelization

Question 19

What type of reaction cause colour change in the following foods? Potato chips, bread crust, roasted meat, roasted nuts

Answer 19

Maillard Browning

Question 20

Define sugar crystallization

Answer 20

Process of evaporating excess water from a sugar solution by heating and formation of sugar crystals upon cooling

Question 21

Define hygroscopic

Answer 21

Ability to absorb water

Question 22

Modified starches are widely used in the food industry. Give 2 examples of products where the use of modified starches contributes to desired characteristics

Answer 22

1) Pre-gelatinization of starch in INSTANT PUDDING (only requires addition of cold water)
2) SAUCES IN FROZEN MEALS (addition of phosphate linkages in modified starch increase freeze stability)

Question 23

Reactions involving carbohydrates include

Answer 23

Caramelization, Maillard browning, Gelatinization, Hydrolysis

Question 24

The __________ and __________ fractions of starch provide the necessary substrates for enzymes to specifically hydrolyze alpha 1-4 or alpha 1-6 linkages between glucose units to release smaller maltose or dextrins

Answer 24

Amylose; amylopectin

Question 25

If you hold an unsalted cracker in your mouth for several minutes, you may notice a slight __________ taste as your saliva breaks down __________ from the cracker

Answer 25

Sweet; starch

Question 26

Starch molecules are not very soluble in __________ water. As temperature increases, starch molecules vibrate more, break intermolecular bonds, and increase _________ bonding to water

Answer 26

Cold; hydrogen

Question 27

Upon cooling of the starch solution and subsequent storage, starch gels are formed, whereby polysaccharide molecules tend to associate with one another due to __________ bonding

Answer 27

Hydrogen

Question 28

Although water control reactions and physical behaviour in foods, it is not the total amount of water that is important, but rather, the __________

Answer 28

Water activity

Question 29

__________ are long-chain polysaccharides primarily found in the spaces between the cells of fruits and vegetables

Answer 29

Pectin

Question 30

Direct heating of sugars will result in a reaction called __________

Answer 30

Caramelization

Question 31

Name 2 plant gums and 2 seaweed polysaccharides

Answer 31

1) PLANT GUMS: Guar Gum and Locust Bean Gum | 2) SEAWEED GUMS: Alginate and Carrageenan

Question 32

Important properties of starches in foods include

Answer 32

1) Poorly soluble in cold water 2) High water holding capacity (important to increase viscosity) 3) Digestible 4) Not sweet