Etiket Arşivleri: Determination of Crude Fat

Extraction And Determination Of Crude Fat From Plant And Animal Tissues ( Ms. Nadia Amara )

Extraction And Determination Of Crude Fat From Plant And Animal Tissues

Ms. Nadia Amara

Introduction of Crude Fat :

Determination of Crude Fat is the term used to refer to the crude mixture
of fat material present in a sample.

Crude fat is the traditional measure of fat in food products.

Fat is important to all aspects of meat production and processing.

Lipids/fats are relatively non-polar molecules, they can be pulled out of a
sample using relatively non-polar solvents. (With a non-polar solvent, only
non-polar molecules in the sample dissolve while polar ones do not ).

The lipid materials may include triglycerides, diglycerides, monoglycerides, phospholipids, steroids, free fatty acids, fat soluble vitamins, carotene pigments, chlorophylls, etc.

Crude fat content is determined by extracting the fat from the sample using
a solvent, then determining the weight of the fat recovered.

The common approach for total crude fat determination is based on the
solubility of lipids in non-polar organic solvents such as hexanes, petroleum
ether, or other non-polar solvent .

In this lab we will determine the crude fat extracted by petroleum ether
solvent .

This method is applicable to extractions of oilseeds, meats, feeds, and foods.

Calculation :

Crude Fat % ( % of Dry matter) = (weight of crude fat + weight of extraction
flask )-(weight of extraction flask) / weight of sample *100

Principle of Soxhlet extraction :

Soxhlet extraction is a continuous solid / liquid extraction.

A solid which contains the material to be extracted is placed in what is called a thimble.

A thimble is made out of a material which will contain the solid but allow liquids to pass through. A lot like filter paper.

The thimble containing the material is placed in the Soxhlet extractor.

An organic solvent is then heated . As it boils its vapors rise up and are
condensed by a condenser. The condensed solvent then fills up the thimble,
and after it fills with enough solvent it automatically siphons back down
into the container of organic solvent.

This process takes place over and over again until all the material to be
extracted from the solid in the thimble is now extracted into the organic
solvent.

This cycle may be allowed to repeat many times, over hours or days.

The advantage of this system is that instead of many portions of warm solvent being passed through the sample, just one batch of solvent is recycled.

After extraction the solvent is removed, typically by means of a rotary evaporator, yielding the extracted compound. The non-soluble portion of the extracted solid remains in the thimble, and is usually discard.

1: Stirrer bar/anti-bumping granules

2: Still pot (extraction pot) – still pot should not be overfilled and the volume of solvent in the still pot should be 3 to 4 times the volume of the soxhlet chamber.

3: Distillation path

4: Soxhlet Thimble

5: Extraction solid (residue solid)

6: Syphon arm inlet

7: Syphon arm outlet

8: Reduction adapter

9: Condenser

10: Cooling water in

11: Cooling water out


Extraction & Determination of Crude Fat From Plant or Animal Tissues ( ABDALQADER A. ABBAS )

INTRODUCTION

The term “lipid” refers to a group of compounds that are soluble in water, but show variable solubility in a number of organic solvents. The lipid content of food determined by extraction with one solvent may be quite different from the lipid content as determined with another solvent of different polarity.

Fat content is determined by often by solvent extraction methods, but it is also can be determined by non-solvent wet extraction methods and by instrumental methods that rely on the physical and chemical properties of lipids.

The method of choice depends on a variety offactors, including the nature of the sample, the purpose of the analysis and instrumentation available.

A Soxhlet extractor is a piece of laboratory apparatus invented in 1879 by Franz von Soxhlet. It was originally designed for the extraction of a lipid from a solid material.

This experiment so uses a soxhlet method to determine the lipid contents of plant & animal tissues.

The Soxhlet method for determining crude fat content is a lengthy process requiring up to a day for a single analysis. The solvent extraction step alone
takes six hours.

The method is therefore not favoured for routine testing purposes in the meat industry, rather it is used as a standard reference method.

In principle, fat is extracted, semi continuously, with an organic solvent.

Solvent is heated and volatized then is condensed above the sample.

Solvent drips onto the sample and soaks it to extract the fat. At 15-20 min interval, the solvent is siphoned to the heating flask, to start the process again.

Fat content is measured by weight loss of sample or weight of fat removed.

OBJECTIVE

1. To extract fat from various plant & animal tissues by an exhaustive extraction using a Soxhlet extractor

2. To determine percent of fat content in a food sample by weight in a sample.

3. To study the function of extraction process by Soxhlet extractor

1: Stirrer bar/anti-bumping granules

2: Still pot (extraction pot) – still pot should not be overfilled and the volume of solvent in the still pot should be 3 to 4 times the volume of the soxhlet chamber.

3: Distillation path

4: Soxhlet Thimble

5: Extraction solid (residue solid)

6: Syphon arm inlet

7: Syphon arm outlet

8: Expansion adapter

9: Condenser

10: Cooling water in

11: Cooling water out

Schematic diagram of a Soxhlet extractor.

THE SOXHLET EXTRACTOR

Continuous extraction of a component from a solid mixture.

Boiling solvent vapors rise up through the larger side-arm

Condensed drops of solvent fall into the porous cup, dissolving out the desired component from a solid mixture

When the smaller side-arm fills to overflowing, it initiates a siphoning action.

The solvent, containing the dissolved component, is siphoned into the boiler below

Residual solvent then drains out of the porous cup, as fresh solvent drops continue to fall into the porous cup.

. . . and the cycle repeats . . .

It should look something like THIS: (only much SLOWER)

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