After the first famous studies of Chevreul on the dissolution of lipid materials in various solvents, it is necessary to jump to when Franz von Soxhlet described the first method based on an automatic solvent extraction diethyl ether for milk lipids Die gewichtsanalytische Bestimmung des MilchfettesDingler's Polytechnisches J,
According to the Soxhlet's procedureoil and fat from solid material are extracted by repeated washing percolation with an organic solvent, usually hexane or petroleum ether, under reflux in a special glassware. In this method the sample is dried, ground into small particles and placed in a porous cellulose thimble.
The thimble is placed in an extraction chamber 2which is suspended above a flask containing the solvent 1 and below a condenser 4. 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 extraction chamber is designed so that when the solvent surrounding the sample exceeds a certain level it overflows and trickles back down into the boiling flask. At the end of the extraction process, which lasts a few hours, the flask containing the solvent and lipid is removed.
In some device a funnel 3 allows to recover the solvent at the end of the extraction after closing a stopcock between the funnel and the extraction chamber. The percentage of lipid in the initial sample can then be calculated. Despite disadvantages of this procedure poor extraction of polar lipids, long time involved, large volumes of solvents, hazards of boiling solventsseveral methods involving automatic solvent extraction were described.
Different automated or semi-automated extraction instruments may be found on the market. Several solvent extraction systems based on the Soxhlet device are on the market to allow fast and safe determination of total lipids in food, soil, As an example, FOSS has launched several types of " Soxtec Systems " including automated or semi-automated analyzers, which extract lipids rapidly and accurately.
These instruments perform boiling, rinsing and solvent recovery. Similarly, Soxtherm extractors from Gerhardt GmbH was developed to reduce extraction times. The sample to be analyzed is weighed into cellulose thimbles and inserted in the extraction device.
An electronic unit can control and monitor up to 4 extraction units individually. It allows batch processing for the extraction of up to fifteen samples at a time and up to samples per day.
Samples are placed into filter bags which prevent sample transfer error. The XT10 automatically recycles solvent and makes it ready for reuse. Solvent is manually added after each extraction. The XT15 Extractor provides a totally automatic operation for up to samples. Four different extraction methods are possible without making any changes to the unit: Soxhlet standard, Soxhlet warm, hot extraction and continuous extraction.
A comparison of different extraction methods for total lipid quantification in meat and meat products was reported Perez-Palacios T et al. The Soxhlet method with previous acid hydrolysis had the same efficiency as that of the method described by Folch.
A microwave-assisted Soxhlet extraction of seed oil sunflower, soybean, rape was described using a cellulose cartridge placed into a quartz extraction vessel inserted in a modified Microdigest device Prolabo.
This procedure is slightly different from that described for the extraction of dry materials. Despite a 3 h analysis, the time reduction and the lack of need for seed grinding makes this procedure a suitable competitor of the previously described methods Garcia-Ayuso LE et al.
Comparative experiments have shown that no significant differences between the extract obtained by the Folch reference method without fat alterations and the microwave-assisted Soxhlet extraction were detected.
These results demonstrated the applicability of that method for the extraction step in routine analysis of a great quantity of food samples Ruiz-Jimenez J et al. This extraction technique, called microwave-assisted Soxhlet extraction, uses two sources of energy, namely microwaves, applied on the extraction chamber of a modified Soxhlet, and electrical heating applied on the distillation flask.
This system has been used for the determination of oil content and fatty acid composition of various biological materials and foodstuffs.
To overcome some limitations of the analytical process water contenta new and convenient process was designed and developed Virot M et al. A modification of that extraction procedure was proposed taking into account the use of a "green solvent", limonene, instead of hexane Virot M et al.
The proposed method is effective and valuable since no significant difference was obtained when using hexane or limonene for the extraction of oleaginous seeds. A critical evaluation of various solvents systems used for the quantification of microalgal fatty acids with lyophilized samples has been reported McNichol J et al.
Samples were inserted in a stainless steel extraction chamber drained by the extraction fluid hexane.Conventional techniques used for cell disruption and extraction are expensive and are often hindered by low efﬁciencies.
Microwave-assisted extraction offers a possibility for extraction of biochemical components including lipids, pigments, carbohydrates, vitamins and proteins, individually and as part of a bioreﬁnery.
Microwave-assisted extraction (MAE) technique was employed to extract the essential oil from sandalwood (Santalum album L.).
The optimal conditions for microwave-assisted extraction of sandalwood oil were determined. of microwaves and microwave assisted techniques. Reviews on application of microwave technology in extraction of essential oil has been elaborately presented. The mechanochemical method was proposed by Ao et al.
, they synthesized ZnO with an average crystallite size of 21 attheheels.com milling process was carried out for 6 h, producing ZnCO 3 as the zinc oxide precursor.
Calcination of the precursor at °C produced ZnO with a hexagonal structure. extraction yield and reduce the operational costs. Recently, microwave-assisted hydrodistillaton (MAHD) procedures for isolating essential oils have become attractive for use in laboratories and industry due to its effective heating, fast energy transfer and also an environmental friendly extraction technique.
Full_VVL_Listing AlphaAnalyeConversions AA_Without_Matching_A AA_Without_Matching_A KG/GAL Kilograms per gallons KG/BATCH Kilograms per batch.