PREPARASI SAMPEL Pengeringan sampel. Analisis Kadar Lemak dalam Bahan Pangan. PERALATAN SOXHLET Analisis Sifat Fisiko-Kimia Lemak atau. Berat lemak diperoleh dengan cara memisahkan lemak dengan pelarutnya. dll. dietil ksi Soxhlet Prinsip Analisis • Ekstraksi lemak dengan pelarut. Analisa lemak kasar: Metode ekstraksi soxhlet dengan pelarut organik Analisa serat kasar: Fraksi dari karbohidrat yang tidak larut dalam basa dan asam.
|Published (Last):||18 August 2015|
|PDF File Size:||15.58 Mb|
|ePub File Size:||8.79 Mb|
|Price:||Free* [*Free Regsitration Required]|
The speed at which an ultrasonic wave travels through a material depends soxulet the concentration of fat in a food. The percentage of lipid in the initial sample Msample can then be calculated: For high moisture content foods it is often better to use batch solvent or nonsolvent extraction techniques.
Thus foods which are sodhlet entirely lipids, such as olive oil, vegetable oil or lard, can usually be analyzed with little sample preparation. These instruments are finding greater use because of the cost and environmental problems associated with the usage and disposal of organic solvents.
Saponification is the process of breaking down a neutral fat into glycerol and fatty acids by treatment with alkali: Most rheological tests involve applying a force to a material and measuring its flow or change in shape. Economic not to give away expensive ingredients Legal to conform to standards of identity and nutritional labeling laws Health development of low fat foods Quality food properties depend on the total lipid content Processing woxhlet conditions depend on the total lipid content The principle physicochemical characteristics of lipids the “analyte” used to distinguish them from the other components in foods the “matrix” are their solubility in organic solvents, immiscibility soxnlet water, physical characteristics e.
Fatty acid methyl esters by GC Intact triacylglycerols and free fatty acids are not very volatile and are therefore difficult to analyze using GC which requires that the lipids be capable of being volatized in the instrument. The electrical conductivity of lipids is much smaller than that of aqueous substances, and so the conductivity of a food decreases as the lipid concentration increases.
For this reason, this test is now usually referred analisjs as sohlet thiobarbituric acid reactive substances TBARS method.
Prisip kerja dak ekstraksi soxhlet adalah memisahkan senyawa tertentu dari sampel padat dengan menggunakan titik didih tertentu dan zoxhlet tertentu. This technique is therefore an example of a measurement of the reduction in the concentration of reactants.
This procedure is inexpensive and allows rapid analysis of lipids in fatty foods. The soxblet index increases with increasing chain length and increasing unsaturation, whereas the density decreases with increasing chain length and decreasing unsaturation.
The more oxygen that has to be fed into the container, the faster the rate of lipid oxidation. Nevertheless, they are simple to perform and do not require expensive apparatus, and so they are widely used in industry and research. A number of instrument manufacturers have designed modified versions of the Soxhlet method that can be used to determine the total lipid content more easily and rapidly e. Chromatography Chromatography is the most powerful method of monitoring lipid oxidation because it provides a detailed profile lemsk the fatty acids and other molecules present in lipids.
Chromatography can be used to determine the complete profile of molecules present in a lipid. Ethyl ether and petroleum ether are the most commonly used solvents, but pentane and hexane are also used for some foods.
The container is shaken vigorously and the organic solvent and aqueous phase are allowed to separate either by gravity or centrifugation. In many foods the lipid component plays a major role in determining the overall physical characteristics, such as flavor, texture, mouthfeel and appearance.
The aqueous phase is then decanted off, and the concentration of lipid in the solvent is determined by evaporating the solvent and measuring the mass of lipid remaining: The acid value is often a good measure of the break down of the triacylglycrols into free fatty acids, which has an adverse effect on the quality of many lipids.
This is done by titration with sodium thiosulfate and a starch indicator: NMR spectroscopy is routinely used to determine the total lipid concentration of foods.
By measuring the density over a range of temperatures it is possible to determine the solid fat content – temperature profile: Rheology is the science concerned with the deformation and flow of matter.
Solid Fat Content The solid fat content SFC of a lipid influences many of its sensory and physical properties, such as spreadability, firmness, mouthfeel, processing and stability. A fat is poured into a metal container and heated at a controlled rate in an oven.
In addition, most of these sub-groups are ana,isis chemically complex. Nevertheless, foods lipids contain a wide variety of different triacylglycerols, each with their own unique melting point, and so they melt over a wide range of temperatures.
Molecules in the mixture are separated because of their differing affinities for the matrix in the column. All triacylglycerols are esters of glycerol and three fatty acid molecules, nevertheless, the fatty acids can have different chain lengths, branching, unsaturation, and positions on the glycerol molecule. For this reason lipids are usually derivitized prior to analysis to increase their volatility. They are a major source of energy and provide essential lipid nutrients.
It does not determine phospholipids in milk, because they are located in the aqueous phase or at the boundary between the lipid and aqueous phases.
At abalisis end of the extraction process, which typically lasts a few hours, the flask containing the solvent and lipid is removed, the solvent is evaporated and the mass of lipid remaining is measured Mlipid. The fatty acids normally found in foods vary in chain length, degree of unsaturation and position on the glycerol molecule.
These techniques are muchcruder than chromatography techniques, because they only give information analisie the average properties of the lipid components present, e. The lipid is first extracted and then dissolved in an ethanol solution which contains a known excess of KOH.
Nevertheless, they are often expensive to purchase and can only be used for certain types of foods, i. Anqlisis, dimasukkan beberapa batu didih dalam labu alas bulat.
It is difficult to find a single solvent which meets all of these requirements. Indirect information about the average molecular weight and degree of unsaturation of the oils can be obtained by measuring physical properties, such as density or refractive index.
Each type of fat has a different profile of lipids present which determines the precise nature of its nutritional and physiochemical properties.