3. Introduction
Cereal grains are the main source of food for human kind, with total global
yields of over 4780 million tonnes in 2020
three major cereals (maize, rice, and wheat) accounting for almost 90%
Most bread wheat (Triticum aestivum L.) is milled into flour and bran for
human consumption,
The wheat “grain” is actually a single-seeded fruit, called a caryopsis, in
which maternal fruit and seed coats (pericarp and testa, respectively)
surround the embryo and the endosperm.
Dr .Waseem Safdar Biochemistry-II (MIC-635) NDBS - NUMS
4. Introduction
The endosperm itself comprises two tissues.
The outer part comprises a single layer of cells in wheat have thick walls
(and hence high dietary fiber), contain storage lipids (i.e., triacylglycerol)
and globulin storage proteins, and are rich in minerals, vitamins, and
phytochemicals (micronutrients).
By contrast, the central starchy endosperm is the major grain tissue and is
rich in starch and storage proteins, but has lower contents of dietary fiber
and micronutrients.
The outer layers account for 13−15%, the starchy endosperm for about 85%
Dr .Waseem Safdar Biochemistry-II (MIC-635) NDBS - NUMS
5. Principle
Lipid in food present in various forms like monoglycerides, diglycerides,
triglycerides and sterol and free fatty acid and phospholipid and carotenoids
and fat-soluble vitamins.
Lipid is soluble in organic solvent and insoluble in water
fat is extracted from food in combination with the solvent.
The choice of solvents is highly critical for total fat analysis.
The most commonly used solvents are ethyl ether and petroleum ether,
but pentane and hexane are used for extracting oil from grains.
Dr .Waseem Safdar Biochemistry-II (MIC-635) NDBS - NUMS
6. Principle
The Goldfish method is commonly used as a
continuous solvent extraction approach.
Soxhlet method is a semicontinuous solvent
extraction approach.
the sample is soaked completely for 5–10 min in a
solvent and then drain off back into the boiling
flask.
A commercial Soxhlet apparatus is shown
Dr .Waseem Safdar Biochemistry-II (MIC-635) NDBS - NUMS
7. Materials
• Weighing balance
• Soxhlet apparatus
• Drying oven
• Thimble
• Heating mantle, Glass rod
• Desiccator with silica gel
• Hexane (Boiling temperature 65°-70°c)
• Cotton plugs
Dr .Waseem Safdar Biochemistry-II (MIC-635) NDBS - NUMS
8. Method
• First of all, we have to dry the product and remove moisture in order to
facilitate entry of the organic solvent, because moisture restricts the entry
of organic solvent.
• Grind the grains in to powder to increase the surface area,
• Rinse all the glass apparatus by Hexane and dry it in the oven at 102°c
and after removing it keep in the desiccator.
• Weigh 10 gram of grounded and dried sample and place it in the thimble.
• Place the thimble in the soxhlet extractor.
Dr .Waseem Safdar Biochemistry-II (MIC-635) NDBS - NUMS
9. Method
• Take a 150ml round bottom flask and fill the flask with 90 ml Hexane.
• Place the whole setting on a heating mantle and allow the Hexane to boil.
• Continue the extraction process for several hours, almost 6 hours.
• Remove the condensing unit from extraction unit and allow the sample to
cool down.
• Finally, it removes all the lipid. Collect almost all the solvent after
distillation.
• Place the sample in the oven and after removing. Take the weight of the
sample.
Dr .Waseem Safdar Biochemistry-II (MIC-635) NDBS - NUMS
10. Results
Dr .Waseem Safdar Biochemistry-II (MIC-635) NDBS - NUMS
Empty thimble= w1
Thimble with sample= w2
Weight of sample= p
Then crude fat percentage = (w2-w1) ⁄ p × 100
For video: https://www.youtube.com/watch?v=SEicK9UT7pY
11. Conclusion
This method is an efficient method to extract all the fat present in the food.
Hence it is used in oil extraction units for better recovery of oil. It is also used
in the analysis of fat present in the sample.
Dr .Waseem Safdar Biochemistry-II (MIC-635) NDBS - NUMS
