Marjo Halonen

Theoretical aspects of water-holding in meat.

As myofibrils consist of a three-dimensional network of long, solid protein particles with the shortest dimension of less than 20 nm, the theoretical foundations of water-holding in meat should be studied from a colloid or surface chemistry point of view. The classical hypotheses for water-holding in meat are based on electrostatic forces or osmotic forces, which cause the swelling of the myofibrils. The more recent research adds to those the structure of water, whether it is low density water induced by kosmotropic effects dominating in the system, or high density water induced by chaotropes, respectively. The phenomena in the one to three molecules thick water layers on protein surfaces do not, however, explain the bulk water-holding.The interactions of ions and non-polar kosmotropes with water and proteins have a relevant effect on water-holding. The chaotropic/kosmotropic effects of different ions will be of importance especially when reducing sodium contents in meat-based foods. Rough estimates of the surface areas of different constituents of the myofibrils showed that transverse elements have larger contact surfaces with the liquid phase than longitudinal. Therefore, more attention should be paid to heavy meromyosin, Z-line and other elements of molecular size or colloidal size. Short range surface forces seem to dominate theories of water-protein interactions, and the theoretical foundations of bulk water-holding are still lacking. Irrespective of the lack of theoretical explanation on the mechanism of water-holding in meat, the meat industry is able to control the macroscopic behaviour of meat-based ingredients rather well.

Local‐mode effects on the rotational structure of the first stretching overtone band system of stibine, SbH3

A high‐resolution Fourier‐transform infrared spectrum, resolution about 0.006 cm−1, of the first stretching overtone band system of stibine has been measured and rotationally analyzed in detail up to J’=22 for both 121SbH3 and 123SbH3 isotopic species. The rotational levels of the A1 and E vibrational states have been analyzed simultaneously by including vibration–rotation coupling terms in the Hamiltonian for the two isotopic species. The A1/E vibrational energy‐level separation has been found to be 0.0727(8) cm−1 for 121SbH3 and 0.0763(8) cm−1 for 123SbH3 with the A1 state being higher in energy in both cases. Fits including 1445 transitions with the standard deviation of 0.0024 cm−1 for 121SbH3 and 1322 transitions with the standard deviation of 0.0022 cm−1 for 123SbH3 have been obtained by optimizing altogether 33 upper‐state parameters in both cases. A simple local‐mode model is shown to account very well for the vibrational dependence of the rotational constants and the coefficients of vibrationally...

Approaching the local mode limit: the second stretching overtone band system of SbH3 near 5500 cm−1

Abstract A high-resolution Fourier transform infrared spectrum of the second stretching overtone band of stibine, SbH 3 , near 5500 cm −1 has been rotationally analyzed in detail up to J′ = 18 using a model Hamiltonian which treats simultaneously the rotational levels of the two close-lying vibrational states A 1 and E. The vibrational energy level separation has been determined to be 0.0501 (7) cm −1 for 121 SbH 3 and 0.0499(8) cm −1 for 123 SbH 3 . According to the vibration—rotation parameters obtained stibine is near the local mode limit. The vibrational dependence of the effective vibration—rotation parameters has been reproduced well with a simple local mode model.

Rotational analysis of the (2000) stretching vibrational band system of 116SnH4

A high resolution Fourier transform infrared spectrum, resolution (FWHM) 10.5×10−3 cm−1, of the (2000, A1/F2) stretching vibrational band system of 116SnH4 has been measured and analyzed in detail up to J=20. The rotational levels of the two vibrational states A1 and F2 are treated simultaneously by including vibration–rotation coupling terms in the Hamiltonian. 1290 infrared transitions from the ground vibrational state to the excited (2000) states have been included as data in the least squares optimization of 21 Hamiltonian parameters. The standard deviation of the fit obtained is 1.1×10−3 cm−1. The upper state vibrational energy level separation has been determined to be 0.0908 (5) cm−1 with the A1 state being higher in energy than the F2 state. The effective rovibrational parameters are found to satisfy closely the local mode constraints.

A SPHERICAL TOP OR A SYMMETRIC TOP ? A PHOTOACOUSTIC TITANIUM : SAPPHIRE RING LASER SPECTRUM OF THE SIXTH STRETCHING VIBRATIONAL OVERTONE BAND SYSTEM OF 116SNH4

A Doppler limited high resolution photoacoustic titanium:sapphire ring laser spectrum of the sixth stretching vibrational overtone band system of monoisotopic stannane, 116SnH4, has been measured in the wave‐number region 11 970–12 130 cm−1. The spectrum has been rotationally analyzed both using a spherical top and a symmetric top model. The results obtained by both approaches are compared with each other. In addition, the degree of localization of the sixth stretching vibrational overtone of stannane is compared with that of the first and second stretching vibrational overtones. No perturbations due to the bending vibrations are found, which demonstrates the suitability of stannane as a model molecule for studying vibrational localization.

Rotations and local modes in stannane, 116SnH4: Photoacoustic overtone spectra with a titanium:sapphire ring laser

The fifth and the seventh stretching vibrational overtone bands of a monoisotopic stannane sample, 116SnH4, have been recorded with Doppler limited resolution using intracavity photoacoustic technique with a titanium:sapphire ring laser. Both band systems resemble closely symmetric top parallel bands in agreement with local mode predictions. The rotational fine structures of these bands have been analyzed with the symmetric top energy level formula and with a spherical top Hamiltonian which treats the problems as interacting rotational levels of A1 and F2 vibrations. Altogether about 200 vibration–rotation transitions have been assigned for both band systems. The fifth overtone band system shows some minor local perturbations due to interactions with bending states. The seventh overtone band is completely unperturbed. The observed vibration–rotation parameters are in good agreement with the ones calculated from a simple vibrational model.

The second stretching overtone band system of 116 SnH4 at 5539 cm−1: how close to the local mode limit?

Abstract A high-resolution Fourier transform infrared spectrum of the second stretching overtone band system of monoisotopic stannane, 116 SnH 4 , has been measured and rotationally analyzed in detail up to J′ = 17. The rotational levels of the close-lying A 1 and F 2 vibrational states have been treated simultaneously by including vibration—rotation coupling terms in the Hamiltonian. The A 1 /F 2 vibrational energy level separation has been found to be 0.026(2) cm −1 with the A 1 state being higher in energy. 449 infrared transitions were used as data in optimizing 12 upper state parameters, and the standard deviation of the fit obtained is 0.0023 cm −1 . The results are discussed in terms of vibrational localization.