A new and rapid method for the determination of nicarbazin residues in poultry feed, eggs and muscle tissue using supercritical fluid extraction and high performance liquid chromatography.

A simple and rapid method, using supercritical fluid extraction (SFE) with off-line high-performance liquid chromatography for the isolation and determination of nicarbazin, a popular broad-spectrum coccidiostatic drug used principally in poultry, is described. Results show good repeatability with a minimum quantification level of 0.4 microgram g-1 and mean 'spiked' recoveries of 98%, 100% and 99% using poultry feeds (n = 18), eggs (n = 28) and chicken tissue (n = 20), respectively. SFE using carbon dioxide is proposed as an alternative isolation method to the current Association of Official Analytical Chemists (AOAC) procedure which involves the use of large volumes of a harmful solvent (dimethylformamide) and requires a long tedious separation and clean-up regime (6 h) prior to its determination.

A rapid supercritical fluid extraction method for the qualitative detection of 2-alkylcyclobutanones in gamma-irradiated fresh and sea water fish.

2-Alkylcyclobutanones are routinely used as chemical markers for irradiated foods containing lipids. However, current extraction procedures (soxhlet-Florisil chromatography) for the isolation of these markers involve a long and tedious clean-up regime prior to GC-MS identification. A simple and rapid method for the isolation of these markers using carbon dioxide as a super critical fluid is described for low lipid content fish samples (fresh and sea water) irradiated up to 8kGy. The presence of 2-dodecylcyclobutanone (2-DCB), a radiolytic marker, was confirmed in all irradiated fish samples at all doses. This was a clear indication that the fish samples had been irradiated and that both methods of isolation (florisil and supercritical fluid extraction) were capable of qualitatively extracting this marker. Supercritical fluid extraction is proposed as an alternative extraction procedure to the florisil chromatography method currently in use and has the added advantage of a considerably shorter extraction time.

Molecular aspects of cell wall modifications during fruit ripening.

Fruit ripening is associated with cell wall modifications. The present review focuses on cell wall components and the nature of noncovalent and covalent interactions in the primary cell wall. The role of structural protein cross-links are evaluated within the context of cell wall-mediated changes in texture during fruit ripening. The article discusses molecular approaches in fruit cell wall interactions to regulate processes in fruit ripening in order to improve post-harvest textural characteristics.

The effect of intermittent heating on some chemical parameters of refined oils used in Egypt. A public health nutrition concern.

As part of a public health campaign in Egypt, various chemical parameters of oil which are considered good indices in assessing the degree of thermal abuse, oxidation and overall quality (acid values, iodine values, peroxide values, etc.) were studied with respect to different frying oils. Ingestion of decomposition products formed as a results of thermal abuse and oxidation of frying oils are known to lead to a variety of symptoms and diseases (allergies, atherosclerosis, coronary heart disease). Results show that the oil most commonly used by street vendors in Egypt (blend of cotton seed and sunflower oil) is the least suitable for frying, while palm oil on the basis of the various chemical parameters studied, is the ideal choice. However, from the nutritional and public health stand point, the use of saturated oils is to be discouraged. Corn oil is therefore the next best choice from both the chemical and nutritional stand point, and is recommended for public use in a country in which deep-fried vegetable patties ('fallafel') forms the staple food item in the diet.

Selenium in health and disease: a review.

Selenium (Se) was discovered 180 years ago. The toxicological properties of Se in livestock were recognized first; its essential nutritional role for animals was discovered in the 1950s and for humans in 1973. Only one reductive metabolic pathway of Se is well characterized in biological systems, although several naturally occurring inorganic and organic forms of the element exist. The amount of Se available for assimilation by the tissues is dependent on the form and concentration of the element. Se is incorporated into a number of functionally active selenoproteins, including the enzyme glutathione peroxidase, which acts as a cellular protector against free radical oxidative damage and type 1 iodothyronine 5'-deiodinase which interacts with iodine to prevent abnormal hormone metabolism. Se deficiency has been linked with numerous diseases, including endemic cardiomyopathy in Se-deficient regions of China; cancer, muscular dystrophy, malaria, and cardiovascular disease have also been implicated, but evidence for the association is often tenuous. Information on Se levels in foods and dietary intake is limited, and an average requirement for Se in the U.K. has no been established. Available data suggest that intake in the U.K. is adequate for all, except for a few risk groups such as patients on total parenteral nutrition or restrictive diets.