thursday lecture –vegetable oils and waxes reading: textbook, chapter 9

Thursday Lecture –Vegetable Oils and Waxes

Reading: Textbook, Chapter 9

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 Anacardiaceae – some people exhibit allergic reaction

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 originally native?

Vegetable Oils

Plant oils – mostly acylglycerides

Glycerol – 3-carbon “backbone”

Figure 9.3, p. 221

Vegetable Oils

Plant oils – mostly acylglycerides

Glycerol – 3-carbon “backbone”

Acyl groups – mostly fatty acids = chain of carbon atoms

Figure 9.3, p. 221

Triacylglyceride structureFigure 9.3, p. 221

Vegetable Oils

Plant oils – mostly acylglycerides

Glycerol – 3-carbon “backbone”

Acyl groups – mostly fatty acids = chain of carbon atoms

Properties of acyl groups:

1. Length – longer = higher melting point

Figure 9.3, p. 221

Vegetable Oils

Plant oils – mostly acylglycerides

Glycerol – 3-carbon “backbone”

Acyl groups – mostly fatty acids = chain of carbon atoms

Properties of acyl groups:

1. Length – longer = higher melting point

2. Unsaturation – the presence of double-bonds between carbons

Figure 9.3, p. 221

Vegetable Oils

Plant oils – mostly acylglycerides

Glycerol – 3-carbon “backbone”

Acyl groups – mostly fatty acids = chain of carbon atoms

Properties of acyl groups:

1. Length – longer = higher melting point

2. Unsaturation – the presence of double-bonds between carbons

- monounsaturated = has 1 double bond

Figure 9.3, p. 221

Vegetable Oils

Plant oils – mostly acylglycerides

Glycerol – 3-carbon “backbone”

Acyl groups – mostly fatty acids = chain of carbon atoms

Properties of acyl groups:

1. Length – longer = higher melting point

2. Unsaturation – the presence of double-bonds between carbons

- monounsaturated = has 1 double bond

- polyunsaturated = has 2 or more double bonds

Figure 9.3, p. 221

Vegetable Oils

Plant oils – mostly acylglycerides

Glycerol – 3-carbon “backbone”

Acyl groups – mostly fatty acids = chain of carbon atoms

Properties of acyl groups:

1. Length – longer = higher melting point

2. Unsaturation – the presence of double-bonds between carbons

- monounsaturated = has 1 double bond

- polyunsaturated = has 2 or more double bonds

Double bonds generally lower melting point of compound

Figure 9.3, p. 221

Triacylglyceride structureFigure 9.3, p. 221

Vegetable Oils – The Plant View

Why do plants produce oils?

Vegetable Oils – The Plant View

Why do plants produce oils?

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

Vegetable Oils – The Plant View

Why do plants produce oils?

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

Where do plants produce and store oils?

Vegetable Oils – The Plant View

Why do plants produce oils?

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

Where do plants produce and store oils?

Answer: seeds, particularly endosperm or cotyledon(s)

Vegetable Oils – The Human View

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

Box 9.1, p. 222

Vegetable Oils – The Human View

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

Answer: high energy content – we 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

Vegetable Oils – The Human View

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

Answer: high energy content – we retain a craving for fats that was an advantage for our ancestors at a time when it was difficult to obtain fats

What has changed?

- widespread availability of fats/oils

Box 9.1, p. 222

Vegetable Oils – The Human View

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

Answer: high energy content – we retain a craving for fats that was an advantage for our ancestors at a time when it was difficult to 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

Acylglycerides – Health Issues – Consumption Increasing

World Consumption Projected to be up 16% - 1998-2001 Figure 9.2, p. 220

Acylglycerides – Health Issues – Consumption Increasing

World Consumption Projected to be up 12% - 2006-2011 Figure 9.2, p. 220

Acylglycerides – Health Issues

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

Box 9.1, p. 222

Acylglycerides – Health Issues

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

– Correlation between blood cholesterol & heart disease

Box 9.1, p. 222

Acylglycerides – Health Issues

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

– Correlation between blood cholesterol & heart disease

– Plants do not produce cholesterol

Box 9.1, p. 222

Acylglycerides – Health Issues

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

– Correlation between blood cholesterol & heart disease

– Plants do not produce cholesterol

– Correlation – saturated dietary fats arterial plaque formation

Box 9.1, p. 222

Acylglycerides – Health Issues

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

– Correlation between blood cholesterol & heart disease

– Plants do not produce cholesterol

– Correlation – saturated dietary fats arterial plaque formation

Conclusion: exchange saturated for unsaturated fats in foods

Box 9.1, p. 222

Acylglycerides – Health Issues

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

– Correlation between blood cholesterol & heart disease

– Plants do not produce cholesterol

– Correlation – saturated dietary fats arterial plaque formation

Conclusion: exchange saturated for unsaturated fats in foods

Problem: polyunsaturated fats linked to production of free radicals, which are carcinogenic

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

Box 9.1, p. 222

Acylglycerides – Health Issues

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

– Correlation between blood cholesterol & heart disease

– Plants do not produce cholesterol

– Correlation – saturated dietary fats arterial plaque formation

Conclusion: exchange saturated for unsaturated fats in foods

Problem: polyunsaturated fats linked 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” betterBox 9.1, p. 222

Trans Fats

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

Trans Fats

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

Polyunsaturated fats vegetable oils, liquid at room temp.

Trans Fats

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

Polyunsaturated fats vegetable oils, liquid at room temp.

Hydrogenation – bubble hydrogen gas through vegetable oil, increases the saturation

Trans Fats

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

Polyunsaturated fats vegetable oils, liquid at room temp.

Hydrogenation – bubble hydrogen gas through vegetable oil, increases the saturation

Completely saturated hard, like wax – not useful

Trans Fats

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

Polyunsaturated fats vegetable oils, liquid at room temp.

Hydrogenation – bubble hydrogen gas through vegetable oil, increases the saturation

Completely saturated hard, like wax – not useful

Partial saturation creamy consistency, useful for spreads

also more chemically stable, longer shelf life

Trans Fats

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

Polyunsaturated fats vegetable oils, liquid at room temp.

Hydrogenation – bubble hydrogen gas through vegetable oil, increases the saturation

Completely saturated hard, like wax – not useful

Partial saturation creamy consistency, useful for spreads

also more chemically stable, longer shelf life

Problem – creates trans type of bonds – health problems

Omega 3, Omega 6 fats

“Omega n” – refers to position of double bond relative to methyl end of fatty acid

Required in human diet – omega 3, omega 6 types

Associated with health benefits

Extraction of Vegetable OilsBasic Approaches

I. Mechanical Extraction

- cold pressing means no heat applied

- hot pressing means external heart is applied

Note: screw press now widely used – allows continuous processing and separation of residual “cake”

Figure 9.6, 9.7, p. 227

Extraction of Vegetable OilsBasic Approaches

I. Mechanical Extraction

- cold pressing means no heat applied

- hot pressing means external heart is applied

Note: screw press now widely used – allows 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

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

Common Sources of Vegetable OilsPolyunsaturated

- linseed oil (Linum usitatissimum - seeds)

- tung oil (Aleurites fordii – seeds)

Unsaturated

- Safflower (Carthamus – 1-seeded fruits)

- soybean (Glycine max – seeds)

- sunflower (Helianthus annuus – 1-seeded fruits)

- corn oil (Zea mays – germ)

- sesame oil (Sesamum indicum – seeds)

- cottonseed oil (Gossypium – seeds)

- canola oil (Brassica – seeds)

Moderately saturated

- peanut oil (Arachis hypogaea – seeds)

- olive oil (Olea europea – fruit pulp)

Table 9.4, p. 230-1

2005

2007

Traditional Vegetable Oil PlantsLinseed Oil - Flax Sesame Oil

Traditional Oil Crop - OliveCold Pressing of pulp after seeds removed

“extra-virgin” – first press, low oleic acid level – not processed further

Traditional Oil Crop - OliveCold Pressing of pulp after seeds removed

“extra-virgin” – first press, low oleic acid level – not processed further

“virgin” – first press, higher acid level – not processed further

Traditional Oil Crop - OliveCold Pressing of pulp after seeds removed

“extra-virgin” – first press, low oleic acid level – not processed further

“virgin” – first press, higher acid level – not processed further

“refined” – refining methods used odor/flavor altered

“pure” – mixture of refined and virgin oils

Major Oil Crops - Palm

Vegetable fat – solid at room temp

Palm plantation - Thailand

Figure 9.21, p. 240

Major Oil Crops - Soybean

Major Oil Crops - SunflowerFigure 9.12, p. 234

Major Oil Crops - CanolaBrassica napus – “rapeseed” rape Canada: Canadian oil = Canola

Vegetable Oils and Soaps

Hydrolysis of acylglyceride fatty acids + glycerol

Triacylglyceride + alkali (e.g. NaOH – lye) sodium salt of fatty acid + glycerol + water

Soap molecules connect oils with water

Figure 9.5, p. 223

Soaps versus DetergentsDetergents – formed 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 soap no “bathtub ring”

Figure 9.5, p. 223

Thursday Lecture – Medicinal Plants

Reading: Textbook, Chapter 11