Lipids Fatty Acid and Amp Free Essays

string(219) " quantity of oilseeds was needed in order to obtain accuracy and precision results by using standard Soxhlet extraction method, which may be a handicap in analysis of small, rare and precious samples in plant breeding\." The measurement of parameters such as oil and fat content help define product quality for many agricultural and food products. These values are widely used to determine energy content and to calculate the proportions of other food components. In addition oil and fat content significantly affect the texture, perceived quality and the flavour of products. We will write a custom essay sample on Lipids: Fatty Acid and Amp or any similar topic only for you Order Now (Whitney, Rolfes, Crowe, Cameron- Smith, Walsh, 2011). An accurate and precise quantitative and qualitative analysis of lipids in food is important for accurate nutritional labelling, determination of wether food meets standard identity, and to ensure that the product meets manufacturing specifications (Nielsen, 2010). AOAC International (2007) state â€Å"the sample preparation for the lipid analysis depends on the type of food and the nature of the lipids in the food. â€Å" Several preparatory steps are common in lipid analysis. They act to aid extraction by removal of water, reduction of particle size, or separation of the lipid from bound proteins or carbohydrates (Min Ellefson, 2010). To analyse lipids it is necessary to first isolate them quantitatively from nonlipid components. Extraction of lipids from source materials, such as food, animal and plant tissues or microorganisms essay writer uk, should be carried out in a manner that avoids changes in the lipids or leads to formations of artefacts (Christie, 1993). It might be necessary to deactivate enzymes that might hydrolyse lipids via heat treatment. (Vain, Nairn, Reid, 1991). Precaution must be taken to minimise oxidation of lipids, especially those with polyunsaturated fatty acids. Use of antioxidants might prove beneficial when dealing with extractions of lipids with highly unsaturated fatty acids (Carapace Garcia, 2000). Carapace et al, (2000) state the accuracy of direct solvent extraction methods greatly depends on the solubility of the lipids in the solvent used and the ability to separate the lipids from complexes with other macromolecules. The lipid content in food determined by extraction with one solvent may be quite different from the content determined with another solvent of different polarity. Fisheries and Aquaculture department (1986) concluded that solvent extraction techniques are commonly used for the determination of fat content. However they tend to be slow, cumbersome, and require highly skilled personnel. In addition, many of the often-hazardous chemicals used are becoming increasingly unacceptable according to international environmental standards. Despite these issues, solvent extraction continues to be used as a reference measurement for quality control. Nielsen (1994) acknowledged the validity of the fat analysis of a food depends on sampling and the preservation of the sample before analysis. An ideal sample should be as close as possible to its intrinsic properties to the material from which it was taken. Pomeranz and Meloan (1994) states â€Å" a sample is considered satisfactory if the properties under investigation correspond to those of the bulk material within the limits of the test. â€Å" Min and Ellefson (2010) note organic solvent methods, which include Goldfish a continuous method, Soxhlet as a semicontinuous method and Folch as a discontinuous method are commonly used to determine the total lipid content of food. They also note the major uses of these methods include extracting the fat prior to GC analysis, quality control of formulated products, determination of fat content in product development, verifying when fat content is 0. 5g per serving, so nutrient content claim can be made and defat samples prior to fibre analysis. The Association of Analytical Chemists (AOAC) as the standard method for crude fat analysis recognizes Soxhlet. The underlying process is that of fat extracted through repeated washing, with an organic solvent under reflux in special glassware. Extraction efficiencies for different compound classes are highly dependent on the properties of the applied solvents (Johnson Barnett, 2003). In the Soxhlet extraction, usually dry material is subjected to semi-continuous extraction with hexane or petroleum ether (James, 1995). Under these conditions, the method basically determines the content of triacylglycerols and has been reported to incompletely extract phospholipids in the samples (Luque de Castro and Garcia-Ayuso, 1998). When a compound of low solubility such as a lipid needs to be extracted from a solid mixture, Soxhlet extraction can be carried out. This method of extraction is only required where the desired compound has a limited solubility in a solvent and the impurity is insoluble in that solvent. It allows the build up of the solvent in the extraction chamber for between 5 and 20 minutes. It is used for oilseed, nutmeg and other food samples where the moisture content does not exceed 10%. The solvent surrounds the sample and is then siphoned back into the boiling flask. The procedure provides soaking effect and does not permit channelling (AOAC, 1995). AOAC (1995) further qualify this method may be used for quantification of lipids in both low fat and high fat source material. It mainly removes non-polar lipids from samples, as polar lipids are generally scarcely soluble in non-polar solvents. In high moisture foods, predrying of the sample may be necessary. High temperatures may adversely affect the oxidative state of lipids, predrying may be achieved using low temperature drying of the sample under vacuum 100mm Hg at 40C to 50C overnight, or 95C to 100C for 5hour. AOAC (1995) report the most outstanding advantages of the conventional Soxhlet method as the sample repeatedly being brought into contact with the fresh portions of the solvent. Thereby it is helping to displace the transfer equilibrium. It further stimulates the temperature of the system remains relatively high since the heat applied to the distillation flask reaches the extraction cavity. This results in no filtration being required after the leaching step. (Russell, Matthews, Gray, 1980) show further advantages. Sample throughput can be increased by simultaneous extraction in parallel, since the basic equipment is inexpensive. Furthermore there is little specialized training and is non-matrix dependent. Soxhlet extraction provides good lipid recovery but is tedious and impractical to use on a routine basis in industry (Schafer, 1998). Wei et al. (2008) concluded from their research accurate quantitative determination of oil content in oilseed rape plays an important role in varieties breeding for improving oil content in seeds. They noted, large quantity of oilseeds was needed in order to obtain accuracy and precision results by using standard Soxhlet extraction method, which may be a handicap in analysis of small, rare and precious samples in plant breeding. You read "Lipids: Fatty Acid and Amp" in category "Papers" James (1995) outlines disadvantages in using this procedure as length of time required for extraction, and the fact that polar and bound lipids are not removed. The most significant drawbacks of using Soxhlet extraction are the large amount of solvent wasted, which is not only expensive to dispose off, but can itself cause additional environmental problems. Samples are exposed to thermal decomposition of the target compounds, which also cannot be ignored when thermo labile analytes are involved. Luque de Castro and Garcia-Ayuso, (1998) further describe disadvantages in this method when looking at the many phases in the extraction process. These are prone to operator error, resulting in inter-laboratory variations. Soxhlet technique is also restricted to solvent selectivity and is not easily automated Modification of the conventional Soxhlet extractor has been developed to shorten the extraction time by using auxiliary energy and automation, for example, ultrasound-assisted Soxhlet extraction and microwave-assisted Soxhlet extraction (Virot, Tomao, Colnagui, Visinoni, Chemat, 2007). Azeredo, Colnago, Engelsberg, (2000) report on the contrast in standard wet chemistry methods and various secondary techniques such as Gas Chromatography with low field Nuclear Magnetic Resonance (NMR). They conclude NMR provides a fast, direct and user-friendly method for determination of the fat and oil content in food. They also note the technique is based on measurement of the NMR response obtained from fat in a product, and the quantification of the fat content by simple and direct calibration without the use of chemometrics. NMR can be calibrated to cover a concentration range from 0. 5 to 100 percent fat. They report that a single sample of fat can be used as a primary calibration. Azeredo, et al. 2000) further note sample measurement as short, typically about 20 seconds, allowing a high throughput of samples and an efficient laboratory operation. The research indicates minimal sample preparation is required because the entire sample is normally loaded into a test tube and measured directly. Colnago et al. (2011) show that no solvents are required and the analysis of the sample is done in its natural state. Research indicates some samples must be heated to melt the fat so it becomes visible to the NMR. This method has been accredited since 2009. Furthermore Colnago et al. (2011) report NMR as non-destructive, so repeatability of measure is easily made. NMR is temperature sensitive, and with a stabilized magnet temperature of 40C, repeatability and precision are optimized by preconditioning the sample at the temperature. Guillou, Trierweiler, Martin (2005) in a collaborative study involving 16 spectrometers discuss precision and accuracy. They indicate repeatability and reproducibility of quantitative deuterium NMR at the natural abundance. This has been determined according to the ISO norms. Precise quantitative and qualitative analysis of lipids in food is important for accurate nutritional labelling and to ensure that the product meets manufacturing specifications (Nielsen, 2010). Xiao, Mjos, Haugsgjerd. (2012). concluded from their research, soxhlet extraction with polar solvents has a low extraction of polar lipids and the recovery of fatty acids in the extracts was below 50%. This method of analysis is crude and subject to operator error and not likely to have precise repeatable results in analysis of lipids. Jansma et al. (2005) in their study compared solvent extraction, with NMR. Each sample using solvent extraction takes approximately six hours from set-up to completion whereas NMR is processed in less than one minute per sample after set up. A further advantage to NMR is the significantly reduced cost of purchase and disposal of solvents, reduced running cost and environmental benefits associated with reduced solvent usage. References: AOAC International. (1995). Association of Official Analytical Chemists. Official Methods of Analysis (16th ed. );(pp1-10). Gaithersburg, MD:AOAC International AOAC International. (2007). Association of Official Analytical Chemists. Official methods of Analysis of AOAC International (18thed. ). (2005); current through revision 2, (2007)Gaithersburg, MD:AOAC International Azeredo, R. BV. , Colnago, L. A. , Engelsberg. M. (2000). Quantitative analysis using steady-state free precession nuclear magnetic resonance. Organic Analytical Chemistry ,72(11). doi:10. 1021/ac991258e Colnago, L. A. , Azeredo, R. B. V. , Marchi Netto, A. , Andrade, F. D. , Venancio, T. (2011). Rapid analyses of oil and fat content in agri-food products using continuous wave free precision time domain NMR . oi:10. 1002/mrc. 2841 Carrapiso, A. I. , Garcia, C. (2000). Some new extraction techniques and insitu transesterification. Lipids, Development in Lipid Analysis: 35(11),1167-1177. doi: 10. 1007/s11745-000-0633-8 Christie, W. W. (1993). Preparation for lipid extracts from tissues. Advances in lipid methodology-Two. Journal of the American Oil Chemists’ Society,71(11), 1179-1187. doi:10. 1007/BF02540534 Fisheries and Aquaculture department. (1896). The Production of fish meal and oil. FAO Fisheries Technical Paper. (T142) Retrieved from http:www. fao. org/DOCREP/003/x6899E/X6899E00. HTM Golay, P. A. , Giuffrida, F. , Dionisi, F. , Destaillats, F. (2009). Streamlined methods for the resolution and quantification of fatty acids Including trans fatty acid isomers in food products by gas chromotography. Journal of AOAC International. 92(5) Retrieved from http://www. unboundmedicine. com/medline/ebm/record/19916367/ab Guillou, C. , Trierweiler, M. , Martin, G. J. (2005). Repeatability and reproducibility of site-specific isotope ratios in quantitative 2H NMR. Magnetic response in Chemistry. doi:10. 1002/mrc. 1260260611 Johnson,R. B. , Barnett, H. J. (2003). Determination of fat content in fish feed by supercritical fluid extraction and subsequent lipid classification of extract by thin layer chromatography-flame ionization detection. Aquaculture. 216, 263-282. ISSN:0044-8486 James, C. S. (1995). Analytical Chemistry of Food (pp91-105). London, UK : Blackie Academic and professional. Jansma,A. , Chuan, T. , Geierstanger, B. H. , Albrecht, R. W. , Olson, D. L. , Peck, T. L. (2005). Automated Microflow NMR: Routine Analysis of Five- Microliter Samples. Analytical Chemistry of Food. 77(19), 6509-6515. doi:10. 02/ac050936w Luque de Castro, M. D. , Garcia-Ayuso, L. E. (1998). Soxhlet extraction of solid materials: an outdated technique with a promising innovative future. Analytica Chimica Acta 369, 1-10. Min,D. B. Ellefson, W. C. (2010). Fat Analysis,Food Analysis . doi:10. 1007/978-1-4419-1478-1_8 Nielsen,S. (Eds. ). (1994). Introduction to the chemical analysis of foods. (pp183-191). Boston, Jones and Bartlett. Nielsen, S. S. ( 2010). Compositional Analysis of food. Food Analysis, (4th ed. ). New York, USA. doi: 10. 1007/978-1-4419-1478-1 Pomeranz,Y. , Meloan, C. F. (1994). Food Analysis: Theory and practice (3rd ed. ). NewYork,Van Nostrand Reinhold. Russell, C. E. , Matthews. M. E. , Gray, I,K. (1980). New Zealand Journal of Dairy Science Technology. 15, 234-244. Schafer, K. (1998). Accelerated solvent extraction of lipids for determining the fatty acid composition of biological material. Analytica Chimica Acta, 358, 69-77. Vian,B. , Nairn,J. , Reid, J. S. G. (1991). Enzyme-gold cytochemistry of seed xyloglucans using two xyloglucan-specific hydrolases. Importance of prior heat-deactivation of the enzyme. The Histochemical Journal, 23(3), 116-1234. oi:10. 1007/BF01047456 Virot,M. , Tomao, V. , Colnaqui. , G. , Visinoni, F. (2007). New Microwave -intergrated Soxhlet extraction an advantageous tool for the extraction of lipid from food products,; Journal of ChromotographyA,1174(1-2), 138-144. doi:org/10. 1016/j. chroma. 2007. 09. 067 Whitney, E. , Rolfes, S. R. , Crowe, T. , Cameron- Smith, D. , Walsh, A. (Ed). (2011). Understanding Nutrition: Aus tralia and New Zealand Edition. South Melbourne, Australia: Cengage Learning Australia Wei, F. , Gao,G. Z. , Wang, X. F. , Dong, X. Y. , Li, P. P. , Hua, W. , Wang, X. , Wu, X. M. , Chen, H. (2008). Quantitative determination of oil content in small quantity of oilseed rape by ultrasound assisted extraction combined with gas chromatography. Ultrasonic Sonochemistry,15(6) 938-42. doi. org/10. 1016/j. ultsonch. 2008. 04. 003 Xiao,L. , Mjos, S. A. , Haugsgjerd, B. O. (2012). Efficencies of three common lipid extraction methods evaluated by mass balances of the fatty acids. Journal of Food Composition and Analysis. 25(2), 198-207. doi:10. 1016/j. jfca. 2011. 08. 003 How to cite Lipids: Fatty Acid and Amp, Papers