Chem Changes of Olive Oil v.2

7/29/2019 Chem Changes of Olive Oil v.2

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MoFT 2013/14 1

Chemical Changes of Olive Oil

FST 5101 Macro-components of Foods

Law Boon Pin

Suraya HashimDevathaa Nadarajan

Nur Zahidah Syahirah Marzuki

Rumaizah Muhammad


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Chemistry of Olive OilFactors that affect the composition of olive oil:

Olive variety

Edaphoclimatic condition (different soil & climatic conditions)

Harvesting period and technique

Fruit ripening degree

Leaf removal, extraction system

Best olive producing area:

cool region - Tuscany

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Chemistry of Olive Oil Composition of olive oil

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Source: http://www.fao.org/docrep/003/x6545e/X6545E01.htm


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Composition of Olive Oil

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Major Minor

Triacylglycerols :

Myristic acid (C14:0)Oleic Acid (C18:1)

Linoleic Acid (C18:2)

Palmitic Acid (C16:0)

Stearic Acid (C18:0)

Linolenic Acid (C18:3)Arachidic acid (C20:0)

Glycerol, FFA

Phenolic Compound

Tocopherol (Vitamin E), Vitamin K

Pigments: e.g. chlorophyll , carotenoid

Phospholipids

Sterols

Mono- & Diglycerides

Fatty alcohols, waxes, and diverse

aroma compounds


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Fatty Acids in Olive Oil

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Fatty acid Type Percentage (%)

Oleic acid (C18:1) Monounsaturated (Omega-9) 55.0 83.0

Linoleic acid (C18:2) Polyunsaturated (Omega-6) 3.5 21.0Palmitic acid (C16:0) Saturated 7.5 20.0

Stearic acid (C18:0) Saturated 0.5 5

Myristic acid (C14:0) Saturated 0.1 1.2

Arachidic acid (C20:0) Saturated 0.1 0.3

Linolenic Acid (C18:3)

(-Linolenic acid)Polyunsaturated (Omega-3) 0.0 1.5

Source: http://www.oliveoilsource.com/page/chemical-characteristics


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Chemistry of Olive Oil -cont

Tryglycerides in olive oil: OOO > POO > OOL > POL > SOO

Chemical reactions involving olive oil Interesterification

Hydrogenation

Hydrolysis

Oxidation

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Interesterification in Olive Oil Is a process where the fatty acids migrate and

recombine with glycerol in a more randomfashion under certain conditions

The distribution of fatty acids is changed onglycerol backbone, while the nature of the fattyacids remain the same.

Interesterification is often used to increase the

solidity of fat without partial hydrogenation.

This leads to significant changes in physicalproperties of fat such as the melting point.

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Interesterification in Olive Oil

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rearranges the fatty acids on the glycerol backbone of a triglyceride


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Interesterification in Olive OilThe interesterification reaction may be chemical or enzymatic:

CHEMICALLY: spontaneously by heating above the melting

temperature of triglyceride. It is easier and faster in the

presence of metal catalysts.eg: zinc oxide, iron oxide, etc. Or

alkali like NaOH.

*relatively cheap and is used on an industrial scale to produce

plastic saturated fat content in low or no trans fat.

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Interesterification in Olive Oil Enzymatically: (Enzymes such as esterase or acylase act as

catalyst) offers better control of products generated duringthe reaction.

Very specific and can be selected to cleave specific bondsesters, ie occupying a particular position on the molecule.

Conducted at lower temperatures than chemical

interesterification, there is less degradation.

Finally, the interesterification process can produce any type offat or oil includes heavy fats suitable for deep-frying, semi-solid fats to make margarine, or liquid oils for bottling.

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Hydrogenation in Olive Oil Hydrogenation is a

process of forcing H2

into oil at high

temp/pressure As a result, double

bonds in oil open and

becomes single bonds

Catalyst used: usuallynickel, but sometimes

palladium, rhodium

or platinum

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Hydrogenation in Olive Oil Double bonds not only decrease in number but also migrate

during hydrogenation

Oils contain cis- C=Cs and they are not uniform in structure

The purpose of hydrogenation is to increase shelf life and tomake oil more stable

Partial hydrogenation is usually preferred

Isomers of unsaturated fatty acids are formed

Cis- bonds are converted into trans- bonds

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Factors affecting hydrogenation

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Trans Fatty Acids

Usually found in hydrogenated shortenings and margarines

Trans-fat are labeled as saturated fats Increases LDL and lowers HDL

Trans fat is bad for health as its characteristics resemble to saturated

fat

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Hydrolysis in Olive Oil Two types of reaction: chemical hydrolysis

and enzymatic hydrolysis

Enzymatic occurs in olive crop whereaschemical occurs after oil is extracted fromcrop

Enzymatic reaction depends on humidity,temperature, ferment, and various

microorganisms

Hydrolysis is basically a reaction whichsplits the esters using water

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Hydrolysis in Olive Oil Reactions could be conducted using diluted acid or diluted

alkali

Both reactions are heated under reflux

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Diluted Acid Diluted alkali

Reversible reaction Non-reversible reaction

Produce carboxylic acid and

glycerol

Produce salt of a carboxylate and

glycerol


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Hydrolysis in Olive Oil

Hydrolysis using diluted alkali is also

known as saponification because of its

relationship with the soap processing.

Ester linkage is broken to form glycerol

and soap

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Oxidation is one

of the major

causes in olive

oil quality

deterioration.

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Oxidation in Olive Oil


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Initiators of Oxidation

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Heat

Light (Photo-oxidation)

Exposure to oxygen

(triggered when the oil enters in

contact with oxygen in the air,first during the milling process,

and later on during storage in

tanks and bottles).

The more the heat, light and O2exposure, the faster is the

oxidation rate


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Oxidation in Olive Oil

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Figure 1 shows how the oxidation of fatty acids in olive oil

changes with time.


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Effects of Oxidation towards Olive Oil

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Unpleasant odor and flavor:

The more the peroxides present, the more rancid the oil


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Antioxidants in Olive Oils

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Vitamin E (alpha-tocopherol)

Carotenoids

Phenolic compounds (simple phenols:

hydroxytosol and tyrosol)

The more

antioxidants andphenolics present,

the lower the

oxidation rate


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Antioxidants in Olive Oils

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Antioxidant can supply the free radical with a replacement for

its missing electron.


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Conclusion Some products resulting from the chemical changes of olive

oil:

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Cosmetics

Toiletries

Cooking/Dressing Oils

Spreads


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Comparison of Dietary Fats

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Source: Vaclavik, V.A. (1998), Essentials of Food Science, An Aspen Publication, page226

7%

10%

12%

13%

15%

15%

19%

27%

43%

48%

51%

68%

91%

21%

76%

71%

57%

9%

54%

33%

54%

9%

2%

10%

3%

2%

11%

0.05%

1%

1%

1%

8%

0.05%

0.05%

1%

1%

0.05%

1%

0%

61%

14%

16%

29%

75%

23%

48%

19%

47%

49%

39%

28%

7%

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Canola Oil

Safflower Oil

Sunflower Oil

Corn Oil

Olive Oil

Soybean Oil

Peanut Oil

Cottonseed Oil

Lard

Beef Tallow

Palm Oil

Butter Fat

Coconut Oil

Saturated Polyunsaturated Alpha-Linolenic A cid Monounsaturated


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References:

1. http://www.fao.org/docrep/003/x6545e/X6545E01.htm

2. http://www.oliveoilsource.com/page/chemical-characteristics

3. Vaclavik, V.A. (1998). Essentials of Food Science. An Aspen Publication.

Page 226

4. Charley, H. & Weaver, C. (1998). Foods A Scientific Approach. A Merrill

Prentice Hall Publication. Page 241-266

5. http://www.soap-making-resource.com/saponification-table.html

6. http://www.cargillfoods.com/na/en/products/oils-shortenings/solutions/interesterification/index.jsp

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Random Interesterification

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The Characteristics of Oils in Soap

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Oil or fat (acid) SAP Hard/Soft Cleansing Fluffy lather Stable lather Skin care

avocado oil 133.7 soft fair yes no amazing!

coconut oil 191.1 hard great yes no fair

castor oil 128.6 soft fair yes yes great

olive oil 135.3 soft good no no great

palm oil 142 hard great no yes fair

peanut oil 137 soft fair no yes great

soybean oil 135.9 soft good no yes fair

sweet almond oil 137.3 soft good no yes amazing!

jojoba oil 69.5 soft fair no yes great

kukui nut oil 135.5 soft good no yes great

lard 138.7 hard good no yes fair

tallow 140.5 hard good no yes fair

Source: http://www.soap-making-resource.com/saponification-table.html

Documents

Chem Changes of Olive Oil v.2