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Biomedical subjects

J W Howard

Publications and source records attributed to J W Howard.

At least 19 recordsLinked to original sources
PubMed1980

Analytical methodology and reported findings of polycyclic aromatic hydrocarbons in foods.

Various polycyclic aromatic hydrocarbons (PAH) some of which are carcinogenic have been demonstrated to be present in water, air, food soils, etc. and are now considered by experts to be ubiquitous in our environment. During the last decade significant progress has been made in the development of multiresidue methods for the analysis of benzo(a)pyrene and other PAH in food at low microgram/kg (parts per billion levels. However, the majority of the available procedures are lengthy and tedious, which precludes their use as effective monitoring tools. Consequently, much of the effort has been accumulated on the benzo(a)pyrene content of foods which presents an incomplete picture of the total PAH in the food supply. This paper reviews the analytical methodology and the reported findings of PAH in foods, beverages, and related products. It points out the need for future work with respect to improved methods and the development of further information on the presence of PAH contamination of the food supply and total environment.

Cooking↗
PubMed1980

Determination of volatile N-nitrosamines in foodstuffs: I. A new clean-up technique for confirmation by II. A continued survey of foods and beverages.

A clean-up technique has been developed which enables MS confirmation of the identity of a nitrosamine from a sample extract obtained by the mineral oil distillation method. A survey of fried bacons using this technique has confirmed the presence of NPYR at levels of 7-26 micrograms/kg in six of nine samples. NDMA has been found by GC-TEA in 62 of 64 beer samples. Five of the higher levels (from 5.8-7.7 micrograms/kg) have been confirmed by MS, following a direct distillation technique. A survey of 106 market samples of poultry products, Chinese foods and herring meals for volatile nitrosamines was conducted. GC-TEA analyses indicated low levels of several nitrosamines in these samples (less than or equal to 11 micrograms/kg), with the exception of two herring meal samples in which NDMA was confirmed by MS at 2.5 and 2.7 mg/kg.

Animals↗
PubMed1978

Survey of cured meat products for volatile N-nitrosamines: comparison of two analytical methods.

A survey of 106 cured meat samples for 14 volatile N-nitrosamines has been completed. N-Nitrosopyrrolidine has been confirmed in fried bacon at levels ranging from 5 to 75 ppb. Unconfirmed trace levels of N-nitrosodimethylamine have been observed in a variety of cured meat products. The comparison of the multidetection GLC-MS method with the mineral oil distillation TEA method for the determination of volatile N-nitrosamines in foods shows good agreement between the analytical methods, especially at the 10 ppb level, and excellent agreement between the GLC and TEA analyses of an identical sample extract.

Animals↗
PubMed1978

Survey of cured meat products for volatile N-nitrosamines: comparison of two analytical methods.

A survey has been completed of 106 cured meat samples for 14 volatile N-nitrosamines. N-Nitrosopyrrolidine has been confirmed in fried bacon at levels ranging from 5 to 75 ppb. Unconfirmed trace levels of N-nitrosodimethylamine have been observed in a variety of cured meat products. The comparison of the multidetection gas-liquid chromatographic (GLC)-mass spectrometric method with the mineral oil distillation-thermal energy analyzer (TEA) method for the determination of volatile N-nitrosamines in foods shows good agreement between the analytical methods, especially at the 10 ppb level, and excellent agreement between the GLC and TEA analyses of an identical sample extracts.

Animals↗
PubMed1973

Effect of nitrite and nitrate on toxin production by Clostridium botulinum and on nitrosamine formation in perishable canned comminuted cured meat.

Comminuted ham was formulated with different levels of sodium nitrite and nitrate, inoculated with Clostridium botulinum, and pasteurized to an internal temperature of 68.5 C. When added to the meat, nitrite concentrations decreased, and cooking had little effect on them. Nitrite concentrations decreased more rapidly during storage at 27 than at 7 C; however they remained rather constant at formulated levels throughout the experiment at both incubation temperatures. The level of nitrite added to the meat greatly influenced growth and toxin production of C. botulinum. The concentration of nitrite necessary to effect complete inhibition was dependent on the inoculum level. With 90 C. botulinum spores/g of meat, botulinum toxin developed in samples formulated with 150 but not with 200 mug of nitrite per g of meat. At a spore level of 5,000/g, toxin was detected in samples with 400 but not with 500 mug of nitrite per g of the product incubated at 27 C. At lower concentrations of nitrite, growth was retarded at both spore levels. No toxin developed in samples incubated at 7 C. Nitrate showed a statistically significant inhibitory effect at a given nitrite level; however, the effect was insufficient to be of practical value. Analyses for 14 volatile nitrosamines from samples made with varying levels of nitrite and nitrate were negative at a detection level of 0.01 mug of nitrite or nitrate per g of meat.

Animals↗