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.

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The fact that different lipids have different polarities means that it is impossible to select a single organic solvent to extract them all. A major disadvantage of the techniques which rely on measurements of the bulk physical properties of foods are that a calibration curve must be prepared between the physical property of interest and the total lipid content, lemzk this may depend on the type of lipid present and the food matrix it is contained in.

A known weight of oil is placed in an oven at a specified temperature about 65 oC and the time until rancidity is detected is recorded by sensory evaluation or measuring the peroxide value. For high moisture content foods it is often better to xoxhlet batch solvent or nonsolvent extraction techniques. Hasil ekstraksi dipindahkan ke rotary evaporator vacuum untuk diekstrak kembali berdasarkan titik didihnya.

Each instrumental methods has its own advantages and disadvantages, and range of foods to which it can be applied. Instrumental methods The are a wide variety of different instrumental methods available for analiss the total lipid content of food materials.

By definition the iodine value is expressed as the grams of iodine absorbed per g of lipid. Measurement of adsorption of radiationUV-visible: Sample Preparation The preparation of a sample for solvent extraction usually involves a number of steps: 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 processing 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 with water, physical characteristics e.

The fact that it behaves like a gas means that it can easily penetrate into a sample and extract the lipids, while the fact that it behaves like a fluid means that it can dissolve a large quantity of lipids especially at higher pressures. Published on Nov View Download 4.

Praktikum Analisa Pangan – dan Alat Bahan: A wide variety of experimental techniques are available to characterize the rheological properties of food materials. The concentration of oil droplets in concentrated food emulsions can be determined using ultrasonic scattering techniques because the ultrasonic velocity and absorption of ultrasound by lemsk emulsion is related to the soxhle of oil droplets present.

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EKSTRAKSI SOXHLET

Analysis of the types of lipids present in a food usually requires that the lipid be available in a fairly pure form. Stability is expressed as hours of heating until rancidity occurs, which may be determined by detection of a rancid odor or by measuring the peroxide value. Lipid oxidation is an extremely complex process involving numerous reactions that give rise to a variety of chemical and physical changes in lipids: The temperature at which the disc changes shape to a sphere is called the “Wiley melting point”.

The fire point is the temperature at which evolution of volatiles due to the thermal decomposition of the lipids proceeds so quickly that continuous combustion occurs a fire. The lipid to be analyzed is weighed and dissolved in a suitable organic solvent, to which a known excess of iodine chloride is added.

The CO2 extracts the lipid, and forms a separate solvent layer, which is abalisis from the aqueous components. Lipid oxidation is one of the major forms of spoilage in foods, because it leads to the formation of off-flavors and potentially toxic compounds.

Asam lemak Palmiat dan Stearat termasuk golongan asam lemak jenuh sengakan asam oleat, linoleat termasuk asam lemak tak jenuh Ketaren, The ideal solvent for lipid extraction would completely extract all the lipid components from a food, while leaving all the other components behind.

ANALISIS LEMAK

Kedelapan, dilakukan ekstraksi 6 kali sirkulasi pelarut n-heksana. The analytical techniques based on these principles can be conveniently categorized into three different types: Thiobarbituric acid TBA This is one of the most widely used tests for determining the extent of lipid oxidation. Massa jenis densitas hasil ekstraksi dihitung dengan mennggunakan persamaan: An aqueous solution of TBA reagent is added to the flask and the sample is shaken, which causes the polar secondary products to be dissolved in it.

Many of the textural properties that people perceive when they consume foods are largely rheological in nature, e. NMR spectroscopy is routinely used to determine the total lipid concentration of foods. The concentration of certain lipids can be determined by measuring the absorbance of ultraviolet-visible radiation. A variety of methods have been developed to measure the temperature dependence of the solid fat content.

EKSTRAKSI SOXHLET

Ideally, the composition of the sample analyzed should represent as closely as possible that of the food from which it was taken. The temperature at which the fat completely melts and becomes transparent is called the “clear point”. A liquid sample is held at 98 oC while air is constantly bubbled through it. The speed at which an ultrasonic wave travels through a material depends on the concentration of fat in a food.

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The flash point is the temperature at which a flash appears at lekak point on the surface of the sample due to the ignition of volatile gaseous products. Eventually, the solvent builds up in the extraction chamber and completely surrounds the sample.

In addition, they are often dried to remove any residual moisture which might interfere with the analysis. Nevertheless, they are simple to perform analisos do not require expensive apparatus, and so they are widely used in industry and research. Melting point In many situations, it is not necessary to know the SFC over the whole temperature range, instead, only information about the temperature at which melting starts or ends is required.

In this case the aqueous phase would undergo analisls extractions using fresh solvent, then all the solvent fractions would be collected together and the lipid determined by weighing after evaporation of solvent. Even so there is always some concern that the results of accelerated tests do not adequately model lipid oxidation in real systems. A chromatographic analysis involves passing a mixture of the molecules to be separated through a column that contains a matrix capable of selectively retarding the flow of the molecules.

Ekstraksi soxhlet ini juga lemzk disebut dengan ekstraksi padat-cair. Soxhlet Extractions – Soxhlet Extractions Author: Determination of the total fatty acid profile allows one to calculate the type and concentration of fatty acids present in the original lipid sample. Sulfuric acid is mixed with the milk, which digests the protein, generates heat, and analiiss down the fat globule membrane that surrounds the droplets, thereby releasing the fat. Ketiga, dimasukkan kertas saring yang telah berisi sampel dalam ektraktor soxhlet.

The manufacture of many foods relies on a knowledge of the type of lipids present in order to adjust the processing conditions to their optimum values, e. The flask is heated and the solvent evaporates and moves up into the condenser where it is converted into a liquid that trickles into the extraction chamber containing the sample.

The Babcock, Gerber and Detergent methods are examples of nonsolvent liquid extraction methods for determining the lipid content of milk and some other dairy products.