Determination of Crude Fat Content (Soxhlet Extraction) _ A Complete Procedure (AOAC 2003.05)

Summary

This video provides a step-by-step guide for determining the crude fat content in food and feed samples through a Soxhlet extraction method. It covers essential preparations, including creating a thimble, weighing the sample, and using a Soxhlet apparatus with n-hexane as the solvent. The process involves extracting fat, reclaiming hexane, drying the flask, and calculating the fat percentage using specific formulas. Key laboratory tools, such as a balance, filter paper, and hot air oven, are essential for accurate results. The video aims to equip viewers with the knowledge to perform this essential proximate analysis efficiently.

Takeaways

• 😀 Crude fat content determination is crucial for food and feed analysis, particularly in solid samples.
• 😀 The process involves five simple steps: thimble preparation, sample preparation, fat extraction, taking final weight, and calculation.
• 😀 Equipment needed for the analysis includes a balance machine, filter paper, cotton, cellulose thimble, hot air oven, and Soxhlet extractor.
• 😀 The primary solvent used for fat extraction is n-hexane or other anhydrous diethyl ether.
• 😀 Thimble preparation involves creating a narrow filter paper thimble, sealing it, and tearing its weight using a balance machine.
• 😀 A homogenized solid sample (1 to 5 grams) is placed in the thimble for fat extraction.
• 😀 Cotton is added to cover the sample in the thimble, which is then closed and labeled for identification.
• 😀 The prepared sample is placed in a Soxhlet extractor with a flat-bottom flask, and n-hexane is added to begin fat extraction.
• 😀 The Soxhlet extractor operates with a reflux rate of 5 drops per second to ensure effective fat extraction over a 6-hour period.
• 😀 After extraction, the solvent is reclaimed and the flask is dried at 110°C to remove excess hexane before weighing it to calculate the crude fat percentage.

Q & A

What is the purpose of the crude fat determination procedure?

The purpose of the crude fat determination procedure is to measure the fat content in food and feed samples, which is an important aspect of proximate analysis.

Can this method be used for all types of samples?

No, this method is valid only for solid samples.

What are the five steps involved in crude fat determination?

The five steps are thimble preparation, sample preparation, fat extraction, taking the final weight, and calculation of crude fat percentage.

What equipment is required for crude fat analysis?

The equipment required includes a balance machine, filter paper, cotton, cellulose thimble, hot air oven, Soxhlet apparatus, and a solvent like n-hexane or anhydrous diethyl ether.

Why is n-hexane used in this procedure?

N-hexane is used as a solvent because it dissolves fat from the sample, allowing it to be extracted and measured.

What is the role of the Soxhlet extractor in this analysis?

The Soxhlet extractor is used to continuously extract fat from the sample by using n-hexane as a solvent.

How long should the Soxhlet extraction run?

The Soxhlet extraction should run for about 6 hours to ensure complete fat extraction from the sample.

Why is it important to maintain a proper reflux rate during the extraction?

Maintaining a proper reflux rate of 5 drops per second ensures the complete extraction of fat from the sample.

What is the purpose of drying the flask at 110°C in the hot air oven?

The flask is dried at 110°C to remove any remaining solvent (hexane) from the fat, ensuring only the extracted fat is weighed.

How is the crude fat percentage calculated?

The crude fat percentage is calculated using the formula: (W2 - W1) / Ws * 100, where W2 is the weight of the flask with fat, W1 is the weight of the empty flask, and Ws is the weight of the sample.