Effect of low dose gamma radiation on lipids in five different meats.

Five types of meats were irradiated by gamma radiation up to a dose of 10 kGy. The m. longissimus dorsi from pork, lamb and beef was irradiated as well as turkey leg and turkey breast muscle. After irradiation, the lipids were extracted from the muscles to ascertain the effect of irradiation. Peroxide and iodine values along with malonaldehyde concentration were used to assess any damage made to the lipids, and to note any significant differences in these compounds due to the type of muscle tissue. Peroxide and iodine values showed that at low irradiation dose, <10 kGy, there was no significant change in any of the meat lipids. Malonaldehyde concentration changed significantly at the micromolar level due to irradiation dose, but only in turkey breast muscle.

Supercritical fluid extraction of N-nitrosamines in hams processed in elastic rubber nettings.

A method for analysing N-nitrosamines in hams processed in elastic rubber nettings by supercritical fluid extraction (SFE) is described. The study was carried out with the prototype of a commercial extractor with a silica gel adsorption cartridge integrally attached to the variable restrictor. The SFE method was compared with a solid-phase extraction procedure currently used for ham analysis. Both methods used the same gas chromatographic-chemiluminescence detection conditions. No significant difference (p < 0.05) was found between results obtained with the 2 methods. Repeatability standard deviation of the SFE method was 1.7 ppb, with a coefficient of variation (CV) of 2.7%, compared with 2.2 ppb, with a CV of 3.5%, for solid-phase extraction. SFE permits minimal use of solvent and more rapid analysis of nitrosamines.

Laser-Raman investigation of phospholipid-polypeptide interactions in model membranes.

The interaction of aqueous dimyristoyl-phosphatidylcholine liposomes with the polypeptides gramicidin A, poly-L-lysine, valinomycin, and gramicidin S was investigated by means of laser-Raman spectroscopy. Auxiliary data were obtained with differential scanning calorimetry. Studies were carried out over the temperature range of 0--50 degrees C, encompassing the gel phase, the transition region, and the liquid crystalline phase of the liposomes. Conformational changes in the phospholipid molecules were investigated by measuring the intensity of the 1062-cm-1 Raman band which is assigned to C-C stretching vibrations of trans segments. Three different types of phospholipid-polypeptide interactions were indicated by the observed Raman data. They are interpreted as (a) orderly penetration of the phospholipid bilayer by a hydrophobic polypeptide; (b) polar interactions involving primarily the head groups of the phospholipid; and (c) disorderly hydrophobic binding between a polypeptide and the hydrocarbon domain of the phospholipid.