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Centre for Biospectroscopy and Datamodelling Sitemap |
|  | Determination of fatty acid compositions in animal fat tissue, by fast methods such as FTIR and Raman spectroscopyThe eating, storing and processing quality of meat is strongly influenced by its lipid content and fatty acid (FA) composition. The traditional methods used to determine fatty acid composition is most often time consuming (hours), needs trained personnel and a chemistry laboratory. The most used traditional methods are gas and liquid chromatography methods, often with hydrolysation and derivatisation. The aim in the present project is to investigate the potential of using fast (minutes) spectroscopy methods to determine fatty acid compositions. Our projects focus on using Near Infrared (NIR), Fourier Transform Infrared (FTIR) and Raman spectroscopy (RS) as fast measurement methods. All these three methods can measure with different sample presentations. The NIR and RS measurements can be done using fibre optics. This enables measurements with some distance (meters) between the instrument and the sample. A large advance with using fibre optics is also that the sample can be in very different shapes e.g. whole large pieces of meat or even whole carcasses. All three methods can be used in fairly rough industrial environments and laboratories are not needed. The spectra from all these methods are complex, so multivariate data analysis is necessary. Recently we have studied determination of fatty acid composition; marine fatty acids (C22:5 and C22:6), iodine value, polyunsaturated, monounsaturated and saturated fatty acids in melted pork fat using Fourier transform mid-infrared spectroscopy (Flaaten et al. 2005). These two fatty acids reduce the shelf life and meat quality in pork meat. A “Biomodul” sampling system was used, by applying 0.35 µl liquid fat to each of 15 spots on the ZnSe-plate. FTIR spectra were measured from 4000 to 500 cm-1, at resolution 6 cm-1. Fat from 74 pork samples were analyzed. The cross validated partial least square regression (PLSR) models gave prediction errors (root mean square error of cross validation, RMSECV), corresponding correlation coefficients (R) and standard deviation (SD) as presented in Table 1. It was concluded that FTIR is very good to predict FA composition in melted pork fat. Table 1. An overview of FTIR spectroscopy ability to predict fatty acid composition in pork fat. For details see Flaaten et al. 2005 below.
This study also gave good ability for FTIR to classification pork fat into three classes; marine FA 0.5 %, 0.5 marine FA 0.7 % and marine FA 0.7 %. In another study we investigated the ability to predict FA composition in pork adipose tissue using fibre optics with a Ball probe and Raman spectroscopy (Olsen et al. 2007). This instrumental set up, enables the potential to measure FA composition noninvasive directly on pork adipose tissue i.e. directly on the carcass in a slaughter plant. Figure 1 illustrates some Raman spectra with some peaks and the corresponding functional groups. The PLSR prediction results for measurement directly on pork adipose tissue are presented in Table 2. Figure 1. A Raman spectra measured on melted pork fat (solid line) and a Raman spectra measured on pork adipose tissue (dotted line). Table 2. An overview of Raman spectroscopy ability to predict fatty acid composition in pork adipose tissue. For details see Olsen et al. 2007 below. ConstituentsSDRMSECVR
Raman measurement on melted fat gave lower prediction errors and higher corresponding correlation coefficients. It was concluded that Raman spectroscopy could reasonably well predict FA composition directly, using a fibre optic probe, on pork adipose tissue. Involved people Tomas Isaksson Elling Olav Rukke Elisabeth Fjærvold Olsen Financial support Norwegian University of Life Sciences Norwegian government grant Publications Flaaten, A., Bryhni, E.A., Kohler, A., Egelandsdal, B. And Isaksson, T. Determination of C22:5 and C22:6 marine fatty acids in pork fat with Fourier tranform mid-infrared spectroscopy. Meat Science p. 433 – 440, Vol. 69, 2005. |  | |||||||||||||||||||||||||||||||||||||||||
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