Transcript Tuesday Lecture – Spices, Herbs, Perfumes

Thursday Lecture – Hydrogels,
Latexes, Resins
Reading: Textbook, Chapter 10
ASSIGNMENT
Find labels on food products that show each of the following
types of ingredients. Tape or fasten them to a piece of paper,
and highlight the ingredient from each category.
1. Vegetable oil
2. Exudate Gum
3. Extractive Gum
4. Starch
5. Pectin
Due: Tuesday 4/19
Hydrogels
Water-modifying Substances  alter behavior of water
Example = gravy, thickening by starch so water molecules
can no longer move freely
Figures 10.1, 10.2,
p. 245
Hydrogels
Water-modifying Substances  alter behavior of water
Example = gravy, thickening by starch so water molecules
can no longer move freely
Figures 10.1, 10.2,
Classes of Plant-Derived Hydrogels:
p. 245
1. Gums
Hydrogels
Water-modifying Substances  alter behavior of water
Example = gravy, thickening by starch so water molecules
can no longer move freely
Figures 10.1, 10.2,
Classes of Plant-Derived Hydrogels:
p. 245
1. Gums
2. Pectins
Hydrogels
Water-modifying Substances  alter behavior of water
Example = gravy, thickening by starch so water molecules
can no longer move freely
Figures 10.1, 10.2,
Classes of Plant-Derived Hydrogels:
p. 245
1. Gums
2. Pectins
3. Starches
All are polymers of sugars (= polysaccharides)
Gums
Polysaccharides composed of sugars other than glucose:
Arabinose, galactose, mannose, xylose
Figure 10.2, p. 245
Gums
Polysaccharides composed of sugars other than glucose:
Arabinose, galactose, mannose, xylose
- water-soluble, or can absorb water
Figure 10.2, p. 245
Gums
Polysaccharides composed of sugars other than glucose:
Arabinose, galactose, mannose, xylose
- water-soluble, or can absorb water
- gum + water  gel
Figure 10.2, p. 245
Gums
Polysaccharides composed of sugars other than glucose:
Arabinose, galactose, mannose, xylose
- water-soluble, or can absorb water
- gum + water  gel
- only partially digested by people, mostly no adverse effects
Figure 10.2, p. 245
Uses of Gums
As foods:
- “texturize” foods
- emulsifiers – disperse fat and protein molecules evenly in water
Uses of Gums
As foods:
- “texturize” foods
- emulsifiers – disperse fat and protein molecules evenly in water
- prevent formation of ice crystals
- increase shelf life of products
Uses of Gums
As foods:
- “texturize” foods
- emulsifiers – disperse fat and protein molecules evenly in water
- prevent formation of ice crystals
- increase shelf life of products
In medicines:
- used as a binder
Uses of Gums
As foods:
- “texturize” foods
- emulsifiers – disperse fat and protein molecules evenly in water
- prevent formation of ice crystals
- increase shelf life of products
In medicines:
- used as a binder
- laxatives
Uses of Gums
As foods:
- “texturize” foods
- emulsifiers – disperse fat and protein molecules evenly in water
- prevent formation of ice crystals
- increase shelf life of products
In medicines:
- used as a binder
- laxatives
Industrial:
- sizing material – fills in pores in paper, textiles
Uses of Gums
As foods:
- “texturize” foods
- emulsifiers – disperse fat and protein molecules evenly in water
- prevent formation of ice crystals
- increase shelf life of products
In medicines:
- used as a binder
- laxatives
Industrial:
- sizing material – fills in pores in paper, textiles
- lubricants (especially in oil drilling operations)
Sources of Plant Gums - Exudates
Exudate Gums: plant is injured to initiate gum production
- gum arabic, Acacia senegal *
gum tragacanth, Astragalus
Figs. 10.4, 10.5, 10.6, 10.7, p. 247-248
Sources of Plant Gums - Extractives
Extractive gums – from endosperm or wood of Fabaceae species
Locust bean gum – Ceratonia
Guar gum - Cyamopsis * Figure 10.8, p. 249
siliqua, Carob; St. John’s Bread *
Xanthan Gum – Made by Bacterium, Xanthomonas campestris
Fermentation Product – uses various starting materials, both
plant and animal origin
Polysaccharide – somewhat complex structure, useful physical
properties
Note – can be derived from wheat, so it can contain gluten
 Should be avoided by those who are allergic to glutens
Pectins
Figure 10.10, p. 251
Pectins – polysaccharide composed of units of pectic acid and its
derivatives
Different types of pectins – vary in # molecules + methylation
Pectin-rich
mesocarp
Pectins
Figure 10.10, p. 251
Pectins – polysaccharide composed of units of pectic acid and its
derivatives
Different types of pectins – vary in # molecules + methylation
Pectins – found in middle lamella of cell wall, epidermis
Pectin-rich
mesocarp
Pectins
Figure 10.10, p. 251
Pectins – polysaccharide composed of units of pectic acid and its
derivatives
Different types of pectins – vary in # molecules + methylation
Pectins – found in middle lamella of cell wall, epidermis
Pectin-rich
mesocarp
Use of pectins – mostly
in jellies and jams
Pectins
Figure 10.10, p. 251
Pectins – polysaccharide composed of units of pectic acid and its
derivatives
Different types of pectins – vary in # molecules + methylation
Pectins – found in middle lamella of cell wall, epidermis
Pectin-rich
mesocarp
Use of pectins – mostly
in jellies and jams
Sources of pectins:
Apple pomace (residue
after pressing for juice)
Citrus peels
Starches
Polymers of glucose
Figure 10.11, p. 252
Starch: alpha bonds between glucose molecules
Cellulose: beta bonds between molecules of glucose
Starches
Polymers of glucose
Figure 10.11, p. 252
Starch: alpha bonds between glucose molecules
Cellulose: beta bonds between molecules of glucose
Uses: food products, sizing
Latex
Latex = mixture of organic compounds produced in laticifers
Laticifer = cells or groups of cells that form tubes, canals, or networks
Latex may be inelastic or elastic
Rubber – elastic latex composed of polymers
Figs. 10.14, 10.15,
p. 254
Rubber – Hevea brasiliensis
Euphorbiaceae – known for milky latex
(“milky sap”) – in laticifers
Figs. 10.17, 10.18,
10.19, p. 255-256
Guayule – Parthenium argentatum *
Asteraceae – southwestern U.S./Mexico
developed as alternative source of natural
rubber
Figure 10.20, p. 257
Chicle – Manilkara zapota
New World - Sapotaceae
Figure 10.23, p. 259;
Box 10.2, p. 258
Plant Resins
Resins – compounds that are synthesized and secreted into specialized
canals or ducts within the plant, in xylem, phloem, or bark
Chemically: resins are polymerized terpenes, usually + volatile oils
Uses of resins:
- incense (frankincense and myrrh)
Figure 10.24, p. 259
Plant Resins
Resins – compounds that are synthesized and secreted into specialized
canals or ducts within the plant, in xylem, phloem, or bark
Chemically: resins are polymerized terpenes, usually + volatile oils
Uses of resins:
- incense (frankincense and myrrh)
- embalming
Figure 10.25, p. 260
Plant Resins
Resins – compounds that are synthesized and secreted into specialized
canals or ducts within the plant, in xylem, phloem, or bark
Chemically: resins are polymerized terpenes, usually + volatile oils
Uses of resins:
- incense (frankincense and myrrh)
- embalming
- mastic *
- lacquer
- artist’s paints
- naval stores (pines)
Figure 10.26, p. 261
Plant Resins
Resins – compounds that are synthesized and secreted into specialized
canals or ducts within the plant, in xylem, phloem, or bark
Chemically: resins are polymerized terpenes, usually + volatile oils
Uses of resins:
- incense (frankincense and myrrh)
- embalming
Figure 10.27, p. 261
- mastic *
- lacquer
- artist’s paints
- naval stores (pines)
- amber – jewel of plant origin
Student Presentations – Gums, Latex, Resin