Thiamin, riboflavin, and alpha-tocopherol content of exotic meats and loss due to gamma radiation.

Changes in thiamin, riboflavin, and alpha-tocopherol concentrations due to gamma irradiation were followed in alligator, caiman, bison, and ostrich (exotic) meats. The proximate composition showed that the exotic meats generally had lower fat content than domestic animal meats and that the thiamin content of the reptiles was lower. The changes in the vitamins due to irradiation were similar to those previously observed for domestic species. The results indicate that the loss of vitamins in these species is negligible insofar as the American diet is concerned, and that the concept of "chemiclearance" is applicable to exotic meats.

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.

Formation of oxo- and hydroxyfatty acids in irradiated chickens.

Finely ground chicken skin and subcutaneous fat exposed to gamma radiation from (137)Cs at 0-2°C for up to 10 kGy generated oxofatty acids (OFA) and hydroxyfatty acids (HFA) in the glycerides. Both classes were determined as colored derivatives; OFA as 2,4-dinitrophenylhydrazones, and HFA as esters of pyruvic acid 2,6-dinitrophenylhydrazone. The concentration of OFA increased with increasing irradiation dose but not always linearly. Variations in the concentration of both classes were noted and some chicken lipids failed to form both classes. In the samples where OFA were generated in significant quantities, the absorption maximum of the derivatives shifted toward a higher wavelength with increasing dose due ostensibly to the formation of double bond(s) in conjugation with the oxo group. This shift in absorption maximum was initially considered to be a means for detecting irradiation as well as indicating the dose received with fair accuracy. However, in several instances irradiation of a chicken sample did not result in the formation of significant increases in OFA and therefore this method cannot be used as a definitive test.

Effect of gamma radiation on levels of α-tocopherol in red meats and turkey.

The effect of low dose ionizing radiation on free α-tocopherol levels in beef, pork and lamb longissimus dorsi muscle and on turkey leg and breast muscle were determined. The samples were irradiated in air with a (137)Cs source at eight dose levels between 0 and 9.4 kGy at 5 °C. Irradiation resulted in a significant decrease in α-tocopherol levels in all of the meats studied. There were no statistically significant differences in the rate of loss of tocopherol due to species, with the exception of turkey breast. The rate of loss of tocopherol in turkey breast tissue was greater than the other meats. The information obtained in this study may be of use for 'chemiclearance' purposes since the relative effects due to species variation were examined.

Effect of gamma radiation on total tocopherols in fresh chicken breast muscle.

Chicken breasts were irradiated in air with a (137)Cs source at 0.0., 1.0, 3.0, 5.6 and 10.0 kGy at 0-2°C. The fresh muscle tissue was saponified and the total tocopherols were isolated and quantitated using normal phase high performance liquid chromatography with a fluorescence detector. Gamma irradiation of the chicken resulted in a decrease in alpha tocopherol with increasing dose. At 3 kGy and 2°C, the radiation level approved by the FDA to process poultry, there was a 6% reduction in the alpha tocopherol level. No significant changes were observed for gamma tocopherol.

Effect of reductant level in skeletal muscle and liver on the rate of loss of thiamin due to gamma-radiation.

A study was made of thiamin content of the skeletal muscles and livers of pork, chicken and beef after gamma-irradiation. gamma-Radiation from a 137Cs source was used to irradiate the samples with doses of 0, 1.5, 3, 6 and 10 kGy at 2 degrees C. Samples were also titrated with dichlorophenol-indophenol to determine the reducing capacity of the tissues. The rate of loss of thiamin upon irradiation was found to be about three time as as fast in skeletal muscle as it was in liver, and to be a function of the reducing capacity of the tissues, the loss decreasing with increasing reductant titer. For the same amount of thiamin loss, liver could be irradiated to three times the dose as could muscle.

Effect of ionizing radiation on unesterified tocopherols in fresh chicken breast muscle.

The effect of ionizing radiation on free tocopherols in chicken was determined Raw chicken breast muscle with skin and adipose tissue removed was subjected to gamma radiation from a (137)Cs source at 1, 2·25, 5·0, and 10·0 kGy. The chicken was packaged aerobically, and irradiated at 4°C. Free tocopherols were extracted directly from the meat without a saponification step. The tocopherols were resolved using normal phase, high performance liquid chromatography by spectrophotofluorometric detection. Irradiation resulted in a significant linear decrease in alpha and gamma tocopherol with increasing dose levels. At 3 kGy, the maximum level approved by the FDA for poultry, a 15% reduction of free gamma tocopherol and a 30% reduction for free alpha tocopherol were observed.

Enzyme levels in raw meat after low dose ionizing radiation and extended refrigerated storage.

Bovine semimembranosus muscle samples obtained aseptically 24 h after slaughter were irradiated at 1, 5 and 10 kGy between 0 and 4°C and stored at 2°C to determine effects of low level ionizing radiation on tissue-free enzyme levels. Samples were analyzed after 1, 7, 14 and 28 days of storage. Nonspecific proteolysis was measured using (14)C-hemoglobin as the substrate. For determination of possible effect by irradiation on lysosomal enzymes, acid phosphatase and ß-glucuronidase were measured. Assays for acid phosphatase and hemoglobin proteolysis indicated negative relationship between increasing dose and enzymatic activity. At 10 kGy mean reductions in enzymatic activity were 8% and 42%, respectively, ß-Glucuronidase was not affected at this or at the lower levels of radiation. Correlation between dosage and storage time with enzymatic activity was not significant.

Immediate effects of ionizing radiation on the structure of unfrozen bovine muscle tissue.

To measure the immediate changes in the ultrastrcucture of meat induced by ionizing radiation, bovine longissimus dorsi muscle was irradiated with (137) Cs 72 h after slaughter. The temperature of the samples during irradiation was maintained between 0 and 4°C to avoid cellular changes caused by freeze/thaw. Muscle was irradiated at 5, 10, 30 and 50 kGy. At low levels (up to 10 kGy) of radiation, changes in muscle structure were minimal. At levels above 30 kGy major increases in myofibril fragmentation and decreases in the tensile strength of raw and cooked muscles were noted. SDS gel electrophoresis indicated a decrease in myosin. No changes in the ultrastructure were observed using transmission electron microscopy.

Survey of human milk for volatile N-nitrosamines and the influence of diet on their formation.

Human milk was analysed for volatile N-nitrosamines and the influence of diet on their possible presence and formation was assessed. 175 samples were obtained from 16 different nursing women. Analysis of samples collected at random, to ascertain baseline levels, indicated that 76.5% of the human milk samples contained less than 0.2 ppb N-nitrosodimethylamine (minimum level of reliable measurement). No other volatile nitrosamines were detected. Expressed milk was collected from volunteers over a 6-hr period after eating meals which included bacon (a source of performed nitrosamines) and at times a vegetable high in nitrate. Eating a meal containing bacon did not result in increased nitrosamine levels in milk. In certain individuals, eating a meal of bacon and a vegetable high in nitrate occasionally resulted in higher levels of N-nitrosodimethylamine in their milk.

Amino acid distribution in brain after use of amphetamines and beta-phenylethylamine.

Amino acids in rat brain were assayed after IP injection d-amphetamine or beta-phenylethylamine (PEA). Results revealed elevated values when one utilized 2.0-12 mg/kg of d-amphetamine. At 15 mg/kg, however, all amino acids fell into the control range except tryptophan which was elevated nearly threefold, and methionine which showed a tenfold decrease. When utilizing PEA to induce the behavioral changes only methionine is decreased at all concentrations of PEA. Chlorpromazine did not disturb the amino acid distribution induced by amphetamine or PEA. When haloperidol was utilized as the neuroleptic to prevent behavioral change there was a significant increase above control of all the amino acids including homocysteine. The implications of this are discussed in the text.

Nitrosamine levels in human blood, urine and gastric aspirate following ingestion of foods containing potential nitrosamine precursors or preformed nitrosamines.

In studies of the effect of diet on nitrosamine levels in selected human physiological fluids, volunteers were fed meals containing fish or beef (sources of precursor amines) or bacon (a source of preformed nitrosamines), in combination with spinach and vegetable juice to supply nitrite via possible reduction of nitrate. Blood, urine and gastric contents were sampled periodically for up to 4 hr after feeding. The results of the study indicated that traces of nitrosamines, usually N-nitrosodimethylamine, were present in many samples of blood, urine and gastric contents, even after an 8-hr fast. Eating the test meals led to a slight increase in nitrosamine levels in the blood and stomach contents in a few subjects. The data obtained from this study suggest that gastric formation of nitrosamine does not appear to be an important health factor in normal people, since the levels of nitrosamines found in physiological fluids are not markedly increased after eating.

Interaction between sample preparation techniques and three methods of nitrite determination.

Meat samples containing nitrite and varying concentrations of ascorbate, cysteine, and sodium chloride were prepared for nitrite analysis. The methods used were the AOAC method of dilution and heating; the addition of mercuric chloride, charcoal, and Carrez reagents at 2 different pH values; and direct analysis of sample supernatants with no treatment (control). The effect of these initial conditions and preparation methods on measured nitrite was determined by using 3 different Griess reagent combinations and chemiluminescent and differential pulse polarographic techniques. Systematic variations were observed in samples treated with mercuric chloride, while the addition of Carrez reagents had little or no effect. Best results were obtained by the AOAC dilution/heating method under alkaline conditions, or by charcoal addition followed by chemiluminescent or colorimetric nitrite determination. Statistical analysis of the nitrite concentrations determined in the several samples showed that these 3 procedures were precise to about 5-6% CV, which was not significantly different from the CV value of 4% determined from replicate analyses.

Preliminary observations on amines and nitrosamines in non-normal human gastric contents.

Gastric contents from fasting humans were pooled and analysed for amines. Volatile amines present were dimethylamine, trimethylamine and histamine; non-volatile amines found were cadaverine, putrescine, ethanolamine and tryptamine. Gastric contents from 35 patients, some before and/or after gastric stimulation with histamine or pentagastrin, were analysed for nitrosamines. N-Nitrosodiethylamine (NDEA) (5-30 microgram/kg) was present in four samples, N-nitrosodimethylamine (NDMA) (2 microgram/kg) in two samples and N-nitrosopyrrolidine (NPYR) (6 microgram/kg) in one sample. pH, nitrite and nitrate determinations were made on some samples. Medical diagnosis of patients could not be correlated with the presence of nitrosamines in the gastric contents.