ChulaU Fats

7/28/2019 ChulaU Fats

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The oil and fat products used for edible purposes

can be divided into two distinct classes:

-liquid oils, such as olive oil, peanut oil,soybean oil, or sunflower oil; and

-plastic fats, such as lard, shortening, butter,and margarine.


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Fat and Oil Processing

Crude fat and oil derived from plant and animal sources are

subjected to several commercial refining processes before thefinal products reach the consumer market.

During these processes, water, carbohydrates, proteins,

pigments, as well as phospholipids, free fatty acids, sterols,waxes and tocopherols are removed.


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In general, fat and oil undergo four processing steps:

1. Extraction2. Refining (Neutralization or Degumming)

3. Bleaching4. Deodorization


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Fat and Oil Extraction

Rendering

Mechanical pressingSolvent extraction


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Rendering

more often employed for the extraction of fats from animal

tissues.

oil-bearing tissues are chopped into small pieces and boiled

in water

the oil floats to the surface of the water and skimmed

water, carbohydrates, proteins, and phospholipids remain in

the aqueous phase and are removed from the oil

degumming is also performed during this step to remove

excess phospholipids

the separated proteins are often used as animal feeds or

fertilizers.


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Mechanical Pressing

often used to extract oil from seeds and nuts

shells or hulls of the plant materials are removed and the kernels or meats aregrinded to rupture the cellular structures

the coarse meal is then heated and pressed in hydraulic or screw presses to

extract the oil

In some cases, oil is pressed without heating. Such oil is known as cold-

pressed or virgin oil. It contains the least amount of impurities and is often of

edible quality without further refining.

For seeds or nuts containing a higher oil content than soybeans it became

customary to press the material in screw presses to remove a large proportionof the oil before extraction. Since this prepressing also ruptures the cellular

structures of oil-bearing materials, most of the residual oil is easily removedwith solvents


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Solvent Extract ion

For seeds or nuts containing a higher oil content, not all of the oilis removed during pressing.

Organic solvents such as petroleum ether and hexane can be

added to the pressed cake to recover the residual oil.

The oil-sovent solution will then be separated from the meal.

Finally, the solvent is evaporated from the oil.


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Refining (Neutralization or Degumming)

Free fatty acids, phospholipids, pigments, and waxes in the

extracted oil lead to undesirable properties of the final products.

Many of these impurities can be removed by treating fats at 40

to 85 C with caustic soda (sodium hydroxide) or soda ash(sodium carbonate).


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Bleaching

Bleaching The major purpose of bleaching is the removal or

undesire color materials in the oil.

Heated oil (~85 oC) may be treated with various bleaching

agents such as fuller's earth, activated carbon, or activated

clays.

Many impurities, including chlorophyll and carotenoid pigments,

are adsorbed onto such agents and removed by filtration.

However, bleaching also promotes lipid oxidation since some

natural antioxidants are removed together with the impurities.


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D d i ti


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DeodorizationDeodorization is the final step in the refining of oils.

Deodorization involves the use of steam distillation under reduced

pressure.

In Europe, a deodorization temperature of 175 - 205 C is common, but in

the United States, higher temperatures of 235 - 250 C are usually

employed.

Volatile compounds with undesirable odors and tastes can be driven off,

resulting a odorless product.

The oil produced is referred to as "refined oil" and is ready to be consumed

or for the manufacture of other products.

About 0.01 percent of citric acid is often added during this step to

inactivate pro-oxidant metals such as iron or copper.


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Food Percentages ofTrans-Fatty AcidsButter 3.6Soft Margarine, High in PUFA 5.2Soft Margarine, Low in PUFA 9.1Hard Margarine 12.4Vegetable Oils, Including Safflower,Sunflower, and Soy 0.0Beefburger, Fried or Grilled 0.8Chocolate Cake with Icing 7.1


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Trans fat has both the benefits and drawbacks of a saturated

fat.

- It has a longer shelf life than regular vegetable fat and is solid atroom temperature.

-Trans fat tends to raise "bad" LDL- cholesterol and lower "good"

HDL-cholesterol, although not as much as saturated fat.

-Trans fat is found in margarine, baked goods such as doughnuts

and Danish pastry, deep-fried foods like fried chicken and French-

fried potatoes, snack chips, imitation cheese, and confectionary

fats.


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These processes are used to modify physical properties

of an oil or fat such as melting point and consistency.


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Polymerization of oils


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Peroxide value

Anisidine valueThiobarbituric value


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High saponification value means.


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Iodine Value

High iodine value means..


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High AV means.


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Free fatty acid value

Example:

Tripalmitin sample has an AV of 0.025.

What is the free fatty acid value?


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Peroxide value (PV)


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Anisidine value


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Measure


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ChulaU Fats