Cysteine feeding affects urinary zinc excretion in normal and ethanol-treated rats

Effects of extrusion conditions on physical and nutritional properties of extruded whole grain red sorghum (sorghum spp)

In order to analyze the effects of extrusion temperature (T: 164, 182, 200 °C) and grits moisture content (g/100 g sample) (%M: 14, 16.5, 19) on textural and physicochemical properties of red sorghum extrudates, whole grain flour was extruded according to a factorial experimental design. The higher values for specific mechanical energy consumption (1006.98 J/g) and expansion (3.36) were obtained at 164 °C-14%M and for sensorial hardness at 164 °C-19%M. While for specific volume, the highest value (10.41 cm³/g) was obtained at 200 °C-14%M. Water solubility and water absorption were directly related with T and inversely with M. Microscopic observation of the samples indicates that the greatest cooking degree was obtained at 200 °C-4%M and the lowest at 164 °C-19%M. Extrusion at 182 °C-14%M allows obtaining an expanded product with good properties. Proximal composition did not show statistically significant differences with raw sample. Extruded sample showed a 25.4% reduction of available lysine and a 31% increase in protein digestibility.

Higher bioaccessibility of iron and zinc from food grains in the presence of garlic and onion

Bioavailability of micronutrients iron and zinc is particularly low from plant foods. Hence there is a need to evolve a food-based strategy to improve the same to combat widespread deficiencies of these minerals in a population dependent on plant foods. Dietary sulfur-containing amino acids have been reported to improve the mineral status of experimental animals. Our objective was to examine whether sulfur compound-rich Allium spices have a similar potential of beneficially modulating the mineral bioavailability. In this context, we examined the influence of exogenously added garlic and onion on the bioaccessibility of iron and zinc from food grains. Two representative cereals and pulses each were studied in both raw and cooked condition employing two levels of garlic (0.25 and 0.5 g/10 g of grain) and onion (1.5 and 3 g/10 g of grain). The enhancing effect of these two spices on iron bioaccessibility was generally evidenced in the case of both the cereals (9.4-65.9% increase) and pulses (9.9-73.3% increase) in both raw and cooked conditions. The two spices similarly enhanced the bioaccessibility of zinc from the food grains, the extent of increase in cereals ranging from 10.4% to 159.4% and in pulses from 9.8% to 49.8%. Thus, both garlic and onion were evidenced here to have a promoting influence on the bioaccessibility of iron and zinc from food grains. This novel information has the potential application in evolving a food-based strategy to improve the bioavailability of trace minerals and hence contributes to the human health benefit.

A highly digestible sorghum mutant cultivar exhibits a unique folded structure of endosperm protein bodies

The endosperm of a sorghum mutant cultivar, with high in vitro uncooked and cooked protein digestibilities, was examined by transmission electron microscopy and alpha-, beta-, and gamma-kafirins (storage proteins) were localized within its protein bodies. Transmission electron microscopy micrographs revealed that these protein bodies had a unique microstructure related to high protein digestibility. They were irregular in shape and had numerous invaginations, often reaching to the central area of the protein body. Protein bodies from normal cultivars, such as P721N studied here, with much lower uncooked and cooked digestibilities are spherical and contain no invaginations. Immunocytochemistry results showed that the relative location of alpha- and beta-kafirins within the protein bodies of the highly digestible genotype were similar to the normal cultivar, P721N. Gamma-kafirin, however, was concentrated in dark-staining regions at the base of the folds instead of at the protein body periphery, as is typical of normal cultivars. The resulting easy accessibility of digestive enzymes to alpha-kafirin, the major storage protein, in addition to the increased surface area of the protein bodies of the highly digestible cultivar appear to account for its high in vitro protein digestibility.

Study of the micro-organisms associated with the fermented bread (khamir) produced from sorghum in Gizan region, Saudi Arabia

Traditional bread (khamir) was made from sorghum flour of two local varieties, Bayadh and Hamra. The bread was prepared by mixing the sorghum flour with water and spices (onion, garlic, lemon juice and fenugreek) in a 1:0.8 (w/w) ratio and fermented for 24 h at 30 degrees C. Two other fermentations were carried out using an inoculum from the previous fermentation. The micro-organisms were isolated from different plates and identified using different characterization systems. Both total bacterial populations and lactic acid bacteria increased with fermentation time and reached the highest number at 16 h (first fermentation) and at 8 h (second and third fermentation). The content of lactic acid was increased with time to reach 1.2%, but the increase was higher for the second and third fermentations (1.6% each). The pH dropped with time from 6.77 to 4.35 in the first fermentation and from 6.65 to 4.18, and 6.57-3.93, in the second and third fermentations, respectively. The microorganisms, which were isolated and characterized during the 24 h fermentation, included: bacteria (Pediococcus pentosaceus, Lactobacillus brevis, Lact. lactis subsp. lactis, Lact. cellobiosus, Klebsiella oxytoca, Kl. pneumoniae, Enterobacter aerogenes, Ent. sakazakii, Serratia marcescens and Ser. odourifera), moulds (Penicillium sp., Rhizopus sp., Aspergillus niger, Alternaria sp., Fusarium sp. and Mucor sp.) and yeasts (Candida parapsilosis, C. orvegnsis and Rhodotorula glutinis).

The effect of Maillard reaction products on zinc metabolism in the rat

The effect of giving Maillard reaction products (MRP) on zinc metabolism was investigated in the rat. In Expt 1, MRP were prepared by incubating casein with either glucose or lactose under controlled reaction conditions, and were quantified as either 'early' or 'advanced' after estimation of lysine loss and lysine destruction respectively. In Expt 2, the effect of the purified early MRP fructose--lysine (FL) on Zn metabolism was studied. The experimental diets containing 20 mg Zn/kg were given to weanling rats for 21 d. Zn balance was assessed over 9-14 d (Expt 1), or 1-14 d (Expt 2). Femur, liver, kidney and serum Zn concentrations were determined at 21 d. The major effect of the MRP in the casein-sugar mixtures was on urinary Zn excretion. The casein-glucose MRP induced up to a 6-fold increase in the quantity of Zn excreted in the urine. The magnitude of the hyperzincuria increased with the extent of the Maillard reaction. Similar dietary levels of casein-lactose MRP increased urinary Zn loss 2-fold. Free FL had no effect on urinary Zn. Faecal Zn, Zn retention, liver, femur and serum Zn were generally not influenced by giving MRP from casein-sugar mixtures or by giving free FL, although kidney Zn was decreased in rats fed on FL. It was concluded that although urinary Zn excretion can be increased by the presence of MRP in the diet, this is only a minor excretory pathway and would have little influence on overall Zn nutrition in individuals fed on a diet adequate in Zn.

Effect of dietary protein and minerals on calcium and zinc utilization

The utilization of most minerals can be altered not only by varying the dietary levels of protein, carbohydrate, fiber, fat, and vitamins but also by varying the forms of macronutrients fed. Interactions among minerals are frequent and sometimes complex. Thus, all assessments of mineral requirements should include discussions of the effects of interactions on mineral bioavailability. Some of these interactions occur in the gut and affect the absorption of minerals. Other interactions affect the metabolism, transport and storage of minerals, and ultimately their excretion in urine or in endogenous gut secretions.

The effect of sodium selenite toxicity on tissue distribution of zinc, iron, and copper in rats

Male Sprague-Dawley rats were used to determine the effects of suptoxic and toxic concentrations of selenite in the drinking water on tissue distribution of zinc (Zn), iron (Fe), and copper (Cu). Se (as sodium selenite) was provided in drinking water at concentrations of 0, 2, 4, and 8 ppm. At 19 d, half of the rats in 4 and 8 ppm Sesupplemented groups were kept on drinking water alone for additional 13 d. All rats were sacrificed at the end of 32 d of experiment. Heart, liver, and kidney were analyzed for the concentrations of Fe, Zn, and Cu by atomic absorption spectrophotometry and of Se by a fluorometric method.Results indicated that rats receiving 4 and 8 ppm Se in drinking water showed a marked reduction in food intake and a reduced growth rate. These adverse effects were quickly reversed when high Se intake was discontinued. Se toxicity caused minimal change in zinc status, reduced tissue iron concentrations and caused a marked increase in copper contents in heart, liver, and kidney. The latter findings were only partly reversed after removal of Se in drinking water. The accumulation of Cu in the tissues of Se-toxic rats provides the evidence of some interaction between Se and Cu.

Absorption and tissue distribution of zinc, iron and copper by rats fed diets containing lactalbumin, soy and supplemental sulfur-containing amino acids

Zinc, copper and iron utilization was examined in rats fed diets containing 30% lactalbumin (L); 30% soy assay protein (S) or 30% soy assay protein supplemented with 0.26% cysteine (SC), 0.45% methionine (SM), 0.26% cysteine and 0.45% methionine (SCM) or 0.71% cysteine (SXC). Diets L, SC and SCM contained equal amounts of cysteine; diets L, SM and SCM contained equal amounts of methionine; diets L, SCM, SXC contained equal amounts of sulfur-containing amino acids. Rats fed diet L had significantly higher levels of zinc in tibias, kidneys and plasma; higher levels of copper in kidneys; and higher levels of iron in tibias than rats fed diet S. Rats fed diet L also absorbed (apparent and true) significantly more zinc; excreted significantly more zinc of endogenous origin in the feces; and absorbed (apparent) significantly less copper than rats fed diet S. Rats fed the soy diets supplemented with sulfur-containing amino acids, especially diet SXC, tended to have elevated levels of zinc in their tibias and kidneys and greater apparent and true absorptions of zinc than rats fed diet S. Rats fed diet SXC still had significantly lower zinc levels in tissue than rats fed diet L. Apparent absorption of zinc was similar among rats fed diets L, SCM and SXC.