EEB304 LECT16 Oils Spring11

8/10/2019 EEB304 LECT16 Oils Spring11

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Thursday LectureVegetable

Oils and Waxes

Reading: Textbook, Chapter 9


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A Plethora of Peppers

Black Pepper Piper nigrum (Asia)

Red Pepper Capsicum spp. (Mexico/South America)

Melegueta Pepper Aframomum (Africa)

Brazilian (or Pink) Pepper Schinus

Drupe of member of Anacardiaceaesome people exhibit

allergic reaction


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Quiz

1. Two different plants both give us a spice called pepper

Chili pepper (Capsicum) and Black pepper (Piper)which

is native to the Old World and which to the New World?

2. Name a major vegetable oil crop. Where is it originallynative?


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Vegetable Oils

Plant oilsmostly acylglycerides

Glycerol3-carbon backbone

Figure 9.3, p. 221


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Vegetable Oils



Acyl groupsmostly fatty acids = chain of carbon atoms

Figure 9.3, p. 221


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Triacylglyceride structureFigure 9.3, p. 221


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Vegetable Oils




Properties of acyl groups:

1. Lengthlonger = higher melting point

Figure 9.3, p. 221


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Vegetable Oils






2. Unsaturationthe presence of double-bonds between carbons

Figure 9.3, p. 221


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Vegetable Oils







- monounsaturated = has 1 double bond

Figure 9.3, p. 221


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Vegetable Oils








- polyunsaturated = has 2 or more double bonds

Figure 9.3, p. 221


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Vegetable Oils








- polyunsaturated = has 2 or more double bonds

Double bondsgenerally lower melting point of compound

Figure 9.3, p. 221


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Triacylglyceride structureFigure 9.3, p. 221


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Vegetable OilsThe Plant View

Why do plants produce oils?


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Answer: high energy content (caloric value)compact way to

store energy


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store energy

Where do plants produce and store oils?


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store energy

Where do plants produce and store oils?Answer: seeds, particularly endosperm or cotyledon(s)


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Vegetable OilsThe Human

View

Why do people consume vegetable oils (and other fats)?

Box 9.1, p. 222

bl il h


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View


Answer: high energy contentwe retain a craving for fats that was

an advantage for our ancestors at a time when it was difficult to

obtain fats

Box 9.1, p. 222

bl Oil h


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View




obtain fats

What has changed?

- widespread availability of fats/oils

Box 9.1, p. 222

V bl Oil Th H


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View




obtain fats

What has changed?

- widespread availability of fats/oils

- increase in human lifespan

Revealing health issues in high consumption of fats

Box 9.1, p. 222

A l l id H l h I


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AcylglyceridesHealth Issues

Consumption Increasing

World Consumption Projected to be up16% - 1998-2001 Figure 9.2, p. 220

A l l id H l h I


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Consumption Increasing

World Consumption Projected to be up12% - 2006-2011 Figure 9.2, p. 220

A l l id H lth I


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25% of deaths in U.S. due to heart disease (2007) - #1 cause

Box 9.1, p. 222

A l l id H lth I


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Correlation between blood cholesterol & heart disease

Box 9.1, p. 222

A l l id H lth I


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Plants do not produce cholesterol

Box 9.1, p. 222

A l l id H lth I


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Correlationsaturated dietary fatsarterial plaque formation

Box 9.1, p. 222

A l l id H lth I


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Conclusion: exchange saturated for unsaturated fats in foods

Box 9.1, p. 222


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Acylglycerides Health Issues


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Conclusion: exchange saturated for unsaturated fats in foods

Problem: polyunsaturated fatslinked to production of free

radicals, which are carcinogenic

Recommendation: mono-unsaturated fats appear best for health,based on currently available information

Problem: saturated fats taste better

Box 9.1, p. 222


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Trans Fats

Saturated fats (animal fats, tropical vegetable fats)link to

heart disease


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Trans Fats


heart disease

Polyunsaturated fatsvegetable oils, liquid at room temp.


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Trans Fats


heart disease


Hydrogenationbubble hydrogen gas through vegetable oil,

increases the saturation


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Trans Fats


heart disease




Completely saturatedhard, like waxnot useful


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Trans Fats


heart disease





Partial saturationcreamy consistency, useful for spreads

also more chemically stable, longer shelf life


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Trans Fats


heart disease





Partial saturationcreamy consistency, useful for spreads

also more chemically stable, longer shelf life

Problemcreates trans type of bondshealth problems


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Omega 3, Omega 6 fats

Omega n refers to position of double bond relative to

methyl end of fatty acid

Required in human dietomega 3, omega 6 types

Associated with health benefits


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Extraction of Vegetable Oils

Basic Approaches

I. Mechanical Extraction

- cold pressing means no heat applied

- hot pressing means external heart is applied

Note: screw press now widely usedallows

continuous processing and separation of

residual cake

Figure 9.6, 9.7, p. 227


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Extraction of Vegetable Oils

Basic Approaches

I. Mechanical Extraction

- cold pressing means no heat applied

- hot pressing means external heart is applied

Note: screw press now widely usedallows

continuous processing and separation of

residual cake

II. Solvent Extraction- organic solvent (e.g. hexane)

Notes: more efficient (less oil left behind) but

requires processing because solvent must be

removed

Figure 9.6, 9.7, p. 227

i f bl il


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Processing of Vegetable Oils

Refining: use alkali to remove free fatty acids

Degumming: extraction with water to remove mucilaginous material

Bleaching: removal of pigments that produce color

Deodorizing: removal of aromatic compounds through steam heating

Winterizing: removal of particles by precipation at low temperature +

filtering

Hydrogenation: increasing the saturation of fatty acids (use hydrogen

gas + catalyst) raise melting point

Figure 9.8, p. 229

C S f V t bl Oil


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Common Sources of Vegetable OilsPolyunsaturated

- linseed oil (Linum usitatissimum- seeds)- tung oil (Aleurites fordiiseeds)

Unsaturated

- Safflower (Carthamus1-seeded fruits)

- soybean (Glycine maxseeds)

- sunflower (Helianthus annuus1-seeded fruits)

- corn oil (Zea maysgerm)

- sesame oil (Sesamum indicumseeds)

- cottonseed oil (Gossypiumseeds)

- canola oil (Brassicaseeds)

Moderately saturated

- peanut oil (Arachis hypogaeaseeds)

- olive oil (Olea europeafruit pulp)

Table 9.4, p. 230-1


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2005

2007

Traditional Vegetable Oil Plants


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Traditional Vegetable Oil PlantsLinseed Oil - Flax Sesame Oil

Traditional Oil Crop Olive


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Traditional Oil Crop - OliveCold Pressing of pulp after seeds removed

extra-virgin first press, low oleic acid levelnot processed further



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virgin first press, higher acid levelnot processed further



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virgin first press, higher acid levelnot processed further

refined refining methods usedodor/flavor altered

pure mixture of refined and virgin oils

Major Oil Crops PalmFigure 9 21 p 240


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Major Oil Crops - Palm

Vegetable fatsolid at room temp

Palm plantation - Thailand

Figure 9.21, p. 240


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Major Oil Crops Sunflower


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Major Oil Crops - Sunflower

Figure 9.12, p. 234

Major Oil Crops Canola


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Major Oil Crops - CanolaBrassica napusrapeseedrape

Canada: Canadian oil = Canola

V t bl Oil d S


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Vegetable Oils and Soaps

Hydrolysis of acylglyceridefatty acids + glycerolTriacylglyceride + alkali (e.g. NaOHlye)sodium salt of fatty

acid + glycerol + water

Soap molecules connect oils

with water

Figure 9.5, p. 223

Soaps versus Detergents


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Soaps versus DetergentsDetergentsformed from hydrocarbons, connected with sulfonic

acid (SO3), a cation, or a non-ionic polar group

Detergents: less harsh than soaps (less strongly basic in pH)

Also their salts are more soluble than those of soapno bathtub ring

Figure 9.5, p. 223

Th d L M di i l Pl


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Thursday LectureMedicinal Plants

Reading: Textbook, Chapter 11

Documents

EEB304 LECT16 Oils Spring11