In Situ Raman Spectrometric Analysis of Crystallinity and Crystal Polymorphism of Fat in Porcine Adipose Tissue

Abstract

From the adipose tissues of pork carcasses stored in a refrigerator, Raman spectra were observed in situ by a portable Raman spectrometer. The observed Raman spectra, which were almost completely due to fat, showed clear dependence on the refrigeration time and carcass temperature. This dependence reflected an increase in the crystallinity of the fat and a change in the fraction of the β' polymorph. Evidence of changes in the packing order of the aliphatic chains of acylglycerol molecules was obtained, and the changes lasted for a long time after the temperature reached the lowest point (4.3 °C). Possibilities of using Raman spectrometry as a tool for routine monitoring of the conditions of carcasses as well as for research on the improvement of the mechanical strength of the adipose tissue are discussed.

A Raman Spectroscopic Method of Evaluating Fat Crystalline States and Its Application in Detecting Pork Fat

“…A 785-nm laser beam (150 mW) for Raman excitation was defocused on the carcass surface, and backscattered Raman signals were collected and accumulated for 60 s. Temperature at the surface of the carcass was also measured. The crystallinity of the fat -the percent mass of fat in the crystalline phase -can be calculated using Raman bands that originate from a polymethylene chain in the alltrans planar conformation (Motoyama et al 2013). In the crystalline state, polymethylene chains are in an all-trans planar conformation; therefore, the intensity of the bands corresponds to the mass of the crystals.…”

“…In the crystalline state, polymethylene chains are in an all-trans planar conformation; therefore, the intensity of the bands corresponds to the mass of the crystals. Two different Raman indices for crystallinity have been reported (Motoyama et al 2013): where I denotes the integrated intensity of the Raman band at the wavenumber identified by a subscript.…”

“…The percent fraction of the β' polymorph can be calculated by the following equation (Motoyama et al 2013). …”

“…Raman spectra inform us of the vibrational states of molecules, reflecting chemical structure, physical states, and the microenvironment at the molecular level. In meat science, Raman spectroscopy is used to determine the structure and physical states of meat components such as secondary and tertiary protein structures, hydrogen bonding between amino-acid residues, chemical composition of fats, and fat crystalline state (Beattie et al 2008, Motoyama et al 2013, Olsen et al 2007, Pedersen et al 2003, Scheier & Schmidt 2013. These structures are closely related to such important quality traits of meat as texture, nutritional quality, storage performance, and palatability.…”

Raman and SEM‐EDX analyses of the ‘Royal Portal’ of Bordeaux Cathedral for the virtual restitution of the statuary polychromy

“…[1][2][3][4] Some promising uses in the field of medicine and in situ diagnostic can be also found in literature [5,6] as well as in the field of food analysis and agriculture. [7,8] The field of geology, geochemistry and gemmology has also taken advantage of portable Raman instrumentation. [9][10][11][12][13] Portable Raman spectroscopy has become available also for the analysis of cultural heritage, [14][15][16][17] because the use of traditional analytical systems to analyse valuable artworks is almost impossible, because large sampling procedures are forbidden.…”