Pectins and Gums

Question 1

What is dietary fiber?

Answer 1

Dietary fiber is the edible parts of plants or carbs that are resistant to digestion and absorption.

Question 2

What are the important polysaccharides in foods?

Answer 2

Pectins and gums

Question 3

Why are pectins and gums important polysaccharides in foods?

Answer 3

Pectins and gums are important because of their functional properties.

Question 4

What are uses for pectins and gums?

Answer 4

Thickeners, stabilizers and gelling agents.

Question 5

What are pectic substances?

Answer 5

Important constituents of plant tissue

Question 6

What are different types of pectic substances?

Answer 6

Protopectin, pectinic acids, pectins and pectic acid.

Question 7

What is considered as a linear polymer of D-galacturonic acid joined by α-1,4 glycosidic linkages?

Answer 7

Pectic substances

Question 8

Each glycosidic linkage is a _________ bond.

Answer 8

Cross-planar

Question 9

How are pectic substances classified?

Answer 9

Based on the number of methyl ester groups attached to the polymer.

Question 10

Which derivative of pectic substances does not have a methyl group?

Answer 10

Pectic acid

Question 11

Where is protopectin formed?

Answer 11

Protopectin forms in immature fruits

Question 12

Where is pectinic acid formed?

Answer 12

Pectinic acid forms in ripened fruits

Question 13

Where is pectic acid formed?

Answer 13

Over-ripe fruits

Question 14

Which pectic substance forms a gel?

Answer 14

Pectinic Acid

Question 15

Which pectic substnace is insoluble in water?

Answer 15

Protopectin

Question 16

True or False. The degree of esterification varies for pectins.

Answer 16

True

Question 17

What compound needs to be present for low-methoxyl pectins to form a gel?

Answer 17

Calcium

Question 18

What needs to be added to high-methoxyl pectins for a gel to form?

Answer 18

Sugar and acid

Question 19

What is commonly used to form pectin jellies?

Answer 19

High-methoxyl pectins

Question 20

Why is pectin hydrophillic?

Answer 20

Due to the large number of polar hydroxyl groups and charged carboxyl groups

Question 21

True or False. The positive charge on the pectin molecule, coupled with their attraction to water, keeps them apart, so they form a sol.

Answer 21

False. The negative charge does this.

Question 22

How does pectin gel formation occur?

Answer 22

Decrease the forces that attract the pectin molecules for water or increase the forces that attract the pectin molecules to each other.

Question 23

How does sugar help with gel formation?

Answer 23

Sugar competes with water, making water less available to bond with pectin molecules

Question 24

How doe acid help with gel formatin?

Answer 24

Acid reduces the pH and the charge on the pectin molecules. Making the pectin molecules no longer repel each other.

Question 25

What are junction zones?

Answer 25

Attractive forces between molecules that help form the 3D network.

Question 26

What is the purpose of junction zones?

Answer 26

To form pockets that trap water.

Question 27

What was formed when the following occurs: 1) water binds to ionic polar groups on pectin 2) pectin molecules are negatively charged and hydrated 3) they do not react to each other

Answer 27

Pectin sol

Question 28

What was formed when the following occurs: 1) Sugar is added 2) Acid is added

Answer 28

Pectin gel

Question 29

What is something that decrease pectin interaction with water?

Answer 29

Sugar

Question 30

What is something that increases pectin molecules interaction with each other?

Answer 30

Acid, water trapped in network and pectin interacting with junction zones

Question 31

Pectin content of fruit depends on what factors?

Answer 31

The type of fruit and the maturity or ripeness

Question 32

How ca you obtain low-methoxyl pectin?

Answer 32

By demthylating pectin with enzymes, acid or alkaline.

Question 33

What is the critical control point of making jelly?

Answer 33

Boiling time

Question 34

What is a gum?

Answer 34

A group of complex hydrophilic carbohydrates containing thousands of monosaccharides units?

Question 35

What is the most common monosaccharide unit in a gum?

Answer 35

Galactose

Question 36

True or false. Gums are also referred to as hydrocolloids.

Answer 36

True

Question 37

What are characteristics of hydrocolloids?

Answer 37

Highly branched, cannot form gels, form stable aqueous colloidal dispersions or sols, and very viscous

Question 38

True or false. Gum is an insoluble fiber.

Answer 38

False. Gum is a soluble fiber

Question 39

What are 2 examples of seed gums?

Answer 39

Guar bean and locust bean gums?

Question 40

What are seed gums?

Answer 40

Branched polymers containing only mannose and galactose

Question 41

Which seed gum has a higher galactose ratio guar bean or locust bean?

Answer 41

Neither

Question 42

Which seed gum has a higher mannose ratio guar bean or locust bean?

Answer 42

Locust

Question 43

What seed gum stabilizes ice cream?

Answer 43

Guar bean

Question 44

What seed gum is a stabilizer in dairy and processed meat products?

Answer 44

Locust bean

Question 45

What are plant exudates?

Answer 45

Complex, highly branched polysaccharides

Question 46

What are two examples of plant exudates?

Answer 46

Two examples of plant exudates would be gum arabic and gum tragacanth.

Question 47

What plant exudate is highly soluble in water?

Answer 47

Gum arabic

Question 48

What plant exudate forms very viscous sols?

Answer 48

Gum tragacanth

Question 49

What is an application of gum arabic?

Answer 49

Stabilize emulsions and control ice crystallization

Question 50

What is an application of gum tragacanth?

Answer 50

Stabilizer in salad dressings, ice ream and confections. To give a creamy texture to food.

Question 51

How are microbial exudates produced?

Answer 51

Using fermentation by microorganisms

Question 52

What is the most common microbial exudates?

Answer 52

Xanthan

Question 53

What gum forms viscous sols that are stable over a wide pH and temperature?

Answer 53

Xanthan

Question 54

True or false. Seaweed polysaccharides are able to form gels under certain conditions.

Answer 54

True

Question 55

What is agar noted for?

Answer 55

Its strong, transparent, heat-reversible gels

Question 56

Agar contains what?

Answer 56

Agarose and agaropectin

Question 57

Agarose and agaropectin are polymers of what?

Answer 57

β-D- and α-L-galactose

Question 58

Where can you obtain agar?

Answer 58

Red seaweed

Question 59

Where can you obtain alginates?

Answer 59

Brown seaweed

Question 60

Alginates form gel in the presence of what ions?

Answer 60

Calcium

Question 61

True or False. Alginates contain mainly D-mannuronic acid and L-guluronic acid.

Answer 61

True

Question 62

What are 2 forms of cellulose that intend to increase viscosity of foods?

Answer 62

CMC and MC

Question 64

What is a sol?

Answer 64

A fluid colloidal system of two or more components

Question 65

What is a gel?

Answer 65

A non fluid colloidal network or polymer network that is expanded throughout its whole volume by a fluid.

Question 66

In sol formation what promotes gel?

Answer 66

Attraction! Specifically pectin molecules attraction

Question 67

In sol formation what prevents gel formation?

Answer 67

Repulsion! Hydrophilic interactions and water hydration

Question 68

In gel formation how do you decrease repulsion?

Answer 68

Adding sugar or acid

Question 69

What factors affect pectin gel formation?

Answer 69

Degree of methylation, sugar content, pH, Calcium ion, endpoint temperature, boiling time

Question 70

What is the salt form of alginic acid and gum mainly extracted from cell walls of brown algae?

Answer 70

Sodium alginate

Question 71

True or false.Alginate-based hydrogel can be used for encapsulation and biomaterials.

Answer 71

True

Question 72

Alkaline pH produces what color?

Answer 72

Violet-blue or turquoise