Physiological function of Se‐enriched tea fertilised with sodium selenite and naturally high‐Se tea in rats

In order to increase food selenium (Se) content, Se‐enriched tea was produced by fertilising with sodium selenite in low‐Se soil. Five groups of rats were fed a low‐Se diet supplemented with either water (Se‐deficient), sodium selenite or an aqueous extraction of low‐Se tea, Se‐enriched tea or naturally high‐Se tea. The chemical form of Se in Se‐enriched tea and the physiological function in rats fed the different Se sources were determined after 8 weeks. The results showed that organic Se accounted for 80% or more of the Se in Se‐enriched tea fertilised with sodium selenite and naturally high‐Se tea, but no significant differences in the proportion of organic Se and protein Se were found between Se‐enriched tea and naturally high‐Se tea. The Se biological utilisation rates were 65.41, 68.05 and 70.49% for sodium selenite, Se‐enriched tea and naturally high‐Se tea respectively. The Se content of blood and liver and the glutathione peroxidase (GSH‐Px) activity were significantly increased by feeding Se‐enriched tea and sodium selenite compared with low‐Se tea, but a more efficient increase in liver GSH‐Px activity was obtained with Se‐enriched tea than with sodium selenite. No significant differences were found between Se‐enriched tea fertilised with sodium selenite and naturally high‐Se tea, which proved that the biological effectiveness of Se in Se‐enriched tea was higher than that of sodium selenite in increasing liver GSH‐Px activity. Se‐enriched tea fertilised with sodium selenite in low‐Se soil gave the same biological function as naturally high‐Se tea. Therefore Se‐enriched tea is a safe and effective means of increasing the Se intake of both humans and animals in low‐Se areas. © 2000 Society of Chemical Industry     

Determination of selenium concentration in rice and the effect of foliar application of Se‐enriched fertiliser or sodium selenite on the selenium content of rice

Atomic fluorescence spectrophotometry was used to determine the selenium (Se) concentration in 30 rice products of different species from Southern China. The Se level ranged from 0.015 to 0.046 µg g^?1. Considering the average daily individual consumption of rice products in Southern China, the average dietary intake of Se supplied by this source is only 6–18 µg day^?1 for an adult. This low Se intake from rice products is mainly responsible for the low total Se intake of inhabitants in Southern China. Foliar spraying of Se‐enriched fertiliser or sodium selenite with 14–18 g Se ha^?1 in the heading stage of rice growth increased the Se content to 0.178–0.421 µg g^?1 in rice products. The concentration and amount of Se‐enriched fertiliser can be varied to achieve an optimum concentration of Se in rice products. The authors suggest that these Se‐enriched rice products can contribute an increase in Se intake of 50–100 µg day^?1 on average if their Se concentration is controlled in the region of 0.15–0.50 µg g^?1. © 2002 Society of Chemical Industry     

Increased intakes of selenium‐enriched foods may benefit human health

Selenium is an essential nutrient and deficient intakes compromise health in domestic animals and humans. A recommended dietary allowance (RDA) of 55 µg d^?1 has been set for adult males and females in the United States; most North Americans consume more than this amount, but many residents of Europe, Asia and Africa consume less. While there are very few reports of outright Se deficiency in people consuming mixed Western diets that have Se intakes below the RDA, there is evidence that dietary intakes of selenium greater than the requirement may help reduce the risk of cancer, especially prostate cancer, to men. Selenium metabolism depends on the chemical form of Se in the diet, and some forms are better for some actions (e.g., cancer reduction) than other forms. Foods may contain different amounts and chemical forms of Se; consequently the benefits of Se may depend on the particular foods consumed. There are many reports of the chemistry and health benefits of Se from plant foods; animal foods also contain Se, but there are fewer reported studies. Fully understanding the health benefits of Se that may be gained by consumption of Se‐enriched foods will require multidisciplinary approaches by teams of medical researchers, chemists, nutritionists, and agricultural scientists. Copyright © 2007 Society of Chemical Industry     

Side‐Directed Transfer and Presystemic Metabolism of Selenoneine in a Human Intestinal Barrier Model

Scope : Selenoneine, a recently discovered selenium (Se) species mainly present in marine fish, is the Se analogue of ergothioneine, a sulfur‐containing purported antioxidant. Although similar properties have been proposed for selenoneine, data on its relevance to human health are yet scarce. Here, the transfer and presystemic metabolism of selenoneine in an in vitro model of the human intestinal barrier are investigated. Methods and results : Selenoneine and the reference species Se‐methylselenocysteine (MeSeCys) and selenite are applied to the Caco‐2 intestinal barrier model. Selenoneine is transferred in higher amounts, but with similar kinetics as selenite, while MeSeCys shows the highest permeability. In contrast to the reference species, transfer of selenoneine is directed toward the blood side. Cellular Se contents demonstrate that selenoneine is efficiently taken up by Caco‐2 cells. Moreover, HPLC/MS‐based Se speciation studies reveal a partial metabolism to Se‐methylselenoneine, a metabolite previously detected in human blood and urine. Conclusions : Selenoneine is likely to pass the intestinal barrier via transcellular, carrier‐mediated transport, is highly bioavailable to Caco‐2 cells and undergoes metabolic transformations. Therefore, further studies are needed to elucidate its possible health effects and to characterize the metabolism of selenoneine in humans.     

A quick method for identifying radiolytic hydrocarbons in low‐fat‐containing food

BACKGROUND: As radiation‐induced alterations of the lipid fraction of foods are related to their initial fat content, concentrations of fat degradation products used as irradiation markers are expected to be lower when irradiating low‐fat‐containing foods. Thus the sensitivity required when applying analytical methods for identifying irradiation markers in foods eventually depends on their respective amounts of fat. The aim of this study was to perform the qualitative analysis of characteristic hydrocarbons resulting from irradiation of samples with a fat content as low as 25 g kg^?1. RESULTS: A rapid extraction using a small amount of ethyl acetate was the unique sample pretreatment required to accomplish the analysis of radiolytic markers by using on‐line coupling of reverse phase liquid chromatography and gas chromatography with mass spectrometry detection (RPLC/GC/MS). Efficient elimination of the large volumes (up to 2170 µL) directly transferred from LC to GC was achieved by optimising the operation mode of the through‐oven transfer adsorption/desorption system used as interface. CONCLUSION: The reported procedure allowed confirmation, in less than 65 min, of the occurrence of up to five irradiation markers, namely n‐pentadecane, 1‐hexadecene, 1,7‐hexadecadiene, n‐heptadecane and 8‐heptadecene, in cooked ham irradiated at doses as low as 2 kGy. © 2012 Society of Chemical Industry     

富硒酵母的研制

采用微生物合成转化法，将无机硒转化为有机硒，利用啤酒酵母菌种，培养基麦芽汁浓度为10Bx,试管静置8h接种．摇床振荡培养16h，发酵培养30h；硒粉在发酵过程中分批加入。该法操作方便，2000ml发酵液可产干酵母粉178．3850g，硒含量604．5μg／g。(陶然)     

Se in Se‐enriched peanut,and losses during peanut protein preparation

This study determined the Se species in Se‐enriched peanut, and Se losses during peanut protein processing by enzymatic extraction, high‐performance liquid chromatography (HPLC) separation and inductively coupled plasma‐mass spectrometry determination. The study revealed that mixed enzymes (protease and lipase, 2:1 w/w) in Na₂S₂O₃, assisted by 1 h ultrasonic processing, could effectively extract Se speciation from defatted peanut powder. Separation of organic Se by HPLC was optimised using pentafluoropropionic anhydride at a concentration of 0.1% in 2% methanol as mobile phase. Selenomethionine is the dominant Se species in peanut, accounting for 65% of the total Se. During the peanut protein preparation, nearly 37% of Se losses were due to the complexity of the multistage process. The loss can be ascribed to volatilisation, dissolution, degradation or other physical modes of transfer or loss.     

Degradation of N‐(1‐Deoxy‐d‐xylulos‐1‐yl)glycine and N‐(1‐Deoxy‐d‐xylulos‐1‐yl)proline using thermal treatment

The formation and degradation of N‐(1‐Deoxy‐d ‐xylulos‐1‐yl)glycine and N‐(1‐Deoxy‐d ‐xylulos‐1‐yl)proline, derived from the secondary amine Maillard reaction in xylose‐amino acid model solutions, were detailed in this study. The identification and quantitative analysis of N‐(1‐Deoxy‐d‐ xylulos‐1‐yl)glycine and N‐(1‐Deoxy‐d‐ xylulos‐1‐yl)proline were carried out using high‐performance anion‐exchange chromatography and high‐performance liquid chromatography. The formation of intermediate and advanced products derived from N‐(1‐Deoxy‐d‐ xylulos‐1‐yl)glycine and N‐(1‐Deoxy‐d‐ xylulos‐1‐yl)proline was also tested using an UV‐Vis spectrophotometer to gain a better comparing of the degradation process of the two important Maillard reaction products using thermal treatment. Results showed that the degradation of N‐(1‐Deoxy‐d‐ xylulos‐1‐yl)glycine was more significant than N‐(1‐Deoxy‐d‐ xylulos‐1‐yl)proline. Moreover, xylose was tested in the degradation products of both N‐(1‐Deoxy‐d‐ xylulos‐1‐yl)glycine and N‐(1‐Deoxy‐d‐ xylulos‐1‐yl)proline, which indicated that the degradation of N‐substituted 1‐amino‐1‐deoxyketoses was a reversible reaction to form reducing sugar.     

Zinc‐containing yeast extract promotes nonrapid eye movement sleep in mice

Zinc is an essential trace element for humans and animals, being located, among other places, in the synaptic vesicles of cortical glutamatergic neurons and hippocampal mossy fibers in the brain. Extracellular zinc has the potential to interact with and modulate many different synaptic targets, including glutamate and GABA receptors. Because of the central role of these neurotransmitters in brain activity, we examined in this study the sleep‐promoting activity of zinc by monitoring locomotor activity and electroencephalogram after its administration to mice. Zinc‐containing yeast extract (40 and 80 mg/kg) dose dependently increased the total amount of nonrapid eye movement sleep and decreased the locomotor activity. However, this preparation did not change the amount of rapid eye movement sleep or show any adverse effects such as rebound of insomnia during a period of 24 h following the induction of sleep; whereas the extracts containing other divalent cations (manganese, iron, and copper) did not decrease the locomotor activity. This is the first evidence that zinc can induce sleep. Our data open the way to new types of food supplements designed to improve sleep.