3. Determination of lipids • Lipids forms in foods: free and componds • Sparing solubility in water and considerable solubility in organic solvents • Organic solvents: ➢ Ethyl ether ➢ petroleum ether ➢ chloroform-methanol
3. Determination of lipids • Lipids forms in foods: free and componds • Sparing solubility in water and considerable solubility in organic solvents • Organic solvents: ➢ Ethyl ether ➢ petroleum ether ➢ chloroform-methanol
Pretreatment of samples • Grinding: The extraction of dry materials depends on particle size. • Drying: Only part of the lipids can be extracted with ether from moist material, as the solvent cannot penetrate the tissues and the extractant becomes saturated with water and inefficient for lipid extraction
Pretreatment of samples • Grinding: The extraction of dry materials depends on particle size. • Drying: Only part of the lipids can be extracted with ether from moist material, as the solvent cannot penetrate the tissues and the extractant becomes saturated with water and inefficient for lipid extraction
Determination methods • Soxhlet extraction method • Chloroform-methanol method • Acid hydrolyzed method • Rose-Gottlieb method, Babcock method, Gerber method
Determination methods • Soxhlet extraction method • Chloroform-methanol method • Acid hydrolyzed method • Rose-Gottlieb method, Babcock method, Gerber method
Section 2. Determination methods of lipids
Section 2. Determination methods of lipids
1. Soxhlet extraction method • Direct extraction of lipids is often carried out in a Soxhlet. • The sample in an extraction thimble from filter paper), covered with defatted cotton wool to prevent small particles from finding their way into the flask, is placed in the middle part of the apparatus. • The flask is filled with solvent; the condenser attached to a tap; and heating of solvent in the flask started
1. Soxhlet extraction method • Direct extraction of lipids is often carried out in a Soxhlet. • The sample in an extraction thimble from filter paper), covered with defatted cotton wool to prevent small particles from finding their way into the flask, is placed in the middle part of the apparatus. • The flask is filled with solvent; the condenser attached to a tap; and heating of solvent in the flask started