Current knowledge in species-related bioavailability of selenium in food

Selenium is an essential trace element that has raised interest because of its antioxidant and anticancer properties. The beneficial or toxic effect of Se is not only dose-dependent, but also relates to the chemical form of the element and its bioavailability. In this review, recently published data is summarised concerning both Se speciation and Se relative bioavailability in various foodstuffs. In addition, Se bioavailability is discussed in relation to the species-dependent metabolism in humans. In this way, the understanding of the potential health impact of Se species in commonly consumed food is aimed to be improved. It is strongly suggested on the basis of a higher retention and a lower toxicity, that organic Se (especially SeMet, the major species in food) is more recommendable than inorganic Se in the frame of a balanced diet. Further research is however desirable concerning the characterisation of unidentified Se species and determination of their health effects.     

四棱豆硒蛋白与其它硒源的生物利用研究

以雌性SD大鼠为研究对象建立低硒的动物模型,通过灌胃的形式给大鼠分别补充不同剂量的亚硒酸钠、富硒酵母和四棱豆硒蛋白。检测大鼠血清和肝肾中的硒含量、谷胱甘肽过氧化氢酶（GSH-px）、超氧化物歧化酶（SOD）、硫氧还蛋白还原酶（TrxR）的活性和丙二醛（MDA）的含量来比较其生物利用的效果。结果表明:与低硒对照组相比,所有加硒处理组的大鼠血、肝、肾中的硒含量以及所含的硒酶活性均明显提高（P<0.05）,在同一补硒水平上,亚硒酸钠组的肝肾硒含量低于富硒酵母组和四棱豆硒蛋白组（P<0.05）;亚硒酸钠组的血清和肝肾的谷胱甘肽过氧化氢酶（GSH-px）、超氧化物歧化酶（SOD）、硫氧还蛋白还原酶（TrxR）的活性和丙二醛（MDA）的含量都低于富硒酵母组和四棱豆硒蛋白组（P<0.05）。结论:四棱豆硒蛋白和富硒酵母增加大鼠的硒含量高于亚硒酸钠组（P<0.05）,其它硒酶的影响是四棱豆硒蛋白最优,硒蛋白能更好地被低硒大鼠吸收利用。      

不同硒源对灵芝生物富硒的比较研究

利用亚硒酸钠和活化硒矿为硒源对灵芝的生物富硒进行了研究,结果表明,两种硒源对灵芝生物富硒的效果有较大差异,灵芝对亚硒酸钠溶液和活化硒矿水溶液的耐受浓度分别是1000μg/g和30μg/g。利用亚硒酸钠和活化硒矿为硒源的灵芝菌丝体最高总硒含量分别为2639.1μg/g和302.2μg/g,最高富硒率分别是25.4%和60.0%。由此可知,与活化硒矿相比,以亚硒酸钠为硒源的灵芝总硒含量较高,但是以活化的硒矿水溶液为硒源成本低,且可以充分利用我国硒都恩施州的硒矿资源,有重要的实际意义。     

In vivo and in vitro testing for selenium and selenium compounds bioavailability assessment in foodstuff

The assessment of selenium and selenium species bioavailability in foodstuff is of special concern on the context of human nutrition. In vivo (human and animal), and in vitro tests are important approaches for estimating the bioavailability of toxic and essential compounds to humans. An overview on in vivo and in vitro bioavailability assays for releasing selenium and selenium species in foodstuffs is summarized. Se and Se species content in a foodstuff critically influence Se bioavailability and bioactivity to humans and animals. Se bioavailability is affected by foodstuff-matrix major composition and minor components. Foodstuffs processing and/or treatments could enhancement or decrease Se bioavailability. Experimental conditions such as the selection of healthy status of examined people (in in vivo humans approaches), the selection of animal model (in vivo animals approaches), or the selection of GI conditions (in in vitro tests) could determines the results. Thus, international standardized protocol for in vivo and in vitro approaches assessment is mandatory.     

Influence of various selenium sources on selenium concentration in the milk of dairy cows

Selenium (Se) as essential trace element is supplemented in various compounds to rations of food producing animals. In human nutrition the range between Se requirement and upper level is very small (1:3–5). Hence, food of animal origin may contribute to Se supply of humans, but can also offer high amounts of Se and exceed the Se upper level for humans. Therefore the transfer into the milk of inorganic (0.2 and 0.4 mg Se from sodium-selenite) or organic (Se methionine) Se-compounds was tested. Fifteen lactating German Holstein cows were fed diets without supplementation (0.1 mg Se/kg dry matter, DM) or supplemented with inorganic or an organic Se-compound over 3 weeks. Se-supplementation did not significantly influence feed intake, milk yield and composition as well as animal health. Se-concentration of milk increased from 13.3 over 17.6 to 19.7 μg/L in the case of inorganic Se supplementation and from 13.9 over 24.6 to 54.8 μg/L after Se-yeast addition.     

Growth and toxin profiles of Bacillus cereus isolated from different food sources

Eleven strains of Bacillus cereus isolated from milk and meat products have been used to study growth and sporulation profiles in detail. Polymerase chain reaction (PCR) using primers detecting cold shock protein A gene signatures (cspA), showed that none of the strains were the newly suggested species in the B. cereus group, B. weihenstephanensis, comprising psychrotolerant cereus strains, although one of the strains grew at 4 degrees C, two at 6 degrees C and seven grew at 7 degrees C. One of the two strains that grew at 6 degrees C had a maximum growth temperature of 42 degrees C, while the remaining 10 strains all grew at temperature of 43 degrees C or higher. Only three strains grew at 48 degrees C. At 42 degrees C, the generation time varied between 11 and 34 min. Spore germination was much faster for the two strains that grew at 6 degrees C than for the other nine strains in milk at 7 degrees C and 10 degrees C. All strains were cytotoxic and contained the non-haemolytic enterotoxin gene (nhe), 10 strains contained the enterotoxin T gene (bceT), and only six had the gene (hbl) encoding haemolytic enterotoxin. Two strains showed some microheterogeneity in the nhe operon. but contained all three genes. We can conclude that true B. cereus strains can have growth profiles as expected for B. weihenstephanensis, and that nhe and bceT were not correlated with growth profiles. However, the two psychrotolerant strains with minimal growth temperature of 4 degrees C and 6 degrees C did not contain hbl, as judged from our PCR results.     

分光光度法测定不同食品中磷含量及结果分析

目的通过分光光度法对不同种类食品中磷含量进行测定。方法实验使用钒钼黄分光光度法进行方法确认,然后对所选代表性食品进行磷含量测定。结果经方法确认后,本方法的标准曲线方程为Y=0.0345X+0.0021(r~2=0.9999),其线性范围:0.0~15.0μg/m L,检出限:3.49 mg/100 g,灵敏度:1.87%,精密度:1.84%,加标回收率:96.96%~100.00%。所选的代表性食物中磷的含量为:全脂奶粉花生牛奶黄豆婴儿米粉鸡蛋牛肉鲫鱼猪肉鸡肉羊肉脱水胡萝卜丁苏打饼干面包方便面小麦粉大米玉米粉,而且含磷较高的食品其脂肪含量都比较高,含磷较低的都是一些低脂食品。结论本研究测定不同食品中的磷含量,为消费者构建更加健康的饮食结构和养成更加健康的饮食习惯提供参考。不同人群需要合理膳食,正确控制磷的摄入量。     

食品中微量硒测定方法研究进展

硒具有延缓衰老、增强免疫力、预防癌症等功效。人体获取硒的主要来源是食品,本文从光学分析法、电化学分析法、色谱学分析法、联用技术等方面对食品中硒含量检测方法进行了综述。并同时介绍了近年来常用于硒检测的联用技术,以期为食品中硒含量测定方法研究提供参考。      

不同来源DHA提取技术及其在食品工业中的应用进展

二十二碳六烯酸(DHA)不仅是婴幼儿的成长因子,也是成年人不可缺少的营养健康元素。随着人们对健康营养食品需求的增加,DHA的提取分离精度要求也不断提高,同时,人们从常规食物中摄入的DHA量有限,需额外补充,因此DHA强化深加工食品具有良好开发前景。本文结合DHA的来源分类及性质差异,综述了DHA提取分离技术的研究进展,并分析DHA关键生产技术,为DHA提取新技术的开发提供新思路,同时阐述了DHA在食品工业中的应用进展,对DHA在食品工业中的应用前景进行了展望。      

食品中硒的有机形态分析研究进展

硒是人体必不可少的微量元素, 不同形态的硒对人体的功能不同, 其中有机硒在抗氧化、抗癌、抗病毒、提高免疫力等方面对人体有重要作用。人体获取硒的途径主要通过膳食摄取, 如食用天然富硒食品、人工合成有机硒产品及有机硒强化剂等。市场上的富硒食品质量参差不齐, 为合理地评价食品中硒的摄入形态和水平, 对食品中硒的形态及含量的检测是近年来研究的一个重点。本文对食品中有机硒检测分离、形态分析以及含量测定等进行了综述, 并对以液相萃取法和酶解法为主的分离方法, 以气相色谱-电感耦合等离子体质谱法(gas chromatography-inductively coupled plasma spectrometry, GC-ICP-MS)、高效液相色谱-电感耦合等离子体质谱法(high performance liquid chromatography-inductively coupled plasma spectrometry, HPLC-ICP-MS)、高效液相色谱-串联三重四级杆质谱法(high performance liquid chromatography-tandem mass spectrometry, HPLC-MS/MS)以及电泳-电感耦合等离子体质谱法(capillary electrophoresis-inductively coupled plasma spectrometry, CE-ICP-MS)为主的检测方法等研究进展进行了总结, 以期对食品中有机硒的检测提供相应的理论依据, 促进食品中有机硒检测标准的发展。     

Methods of quantitative iodine analysis in food products and food sources

Methods of quantitative iodine analysis in food products and food sources. Advantages and disadvantages of the methods are evaluated methods of iodine analysis.     

生物利用率在食品污染物风险评估中的应用

经口生物利用率是描述物质在胃肠道内释放、吸收、代谢、最终到达循环系统的过程,是外暴露剂量中对机体产生作用的物质比例。基于生理条件模拟人类胃肠道消化、吸收、转运等过程的体外消化模型是目前研究食品中污染物生物利用率的有用工具。食物基质成分及脂肪含量、污染物理化性质、食物中其他营养素含量和机体营养状态等影响物质的生物利用率。本文阐述生物利用率在食品污染物风险评估中的应用。     

Identification and evaluation of volatile odor-active pollutants from different odor emission sources in the food industry

In order to elucidate the nature of different odor-emission sources in the food industry, odor-active pollutants of the exhaust air in the cooling gases from coffee bean roasting, the exhaust air of fish meal production, and the exhaust air of swine breeding were investigated. Knowledge of what pollutants are present in the odor emission and are responsible for the malodor is vital to the development of suitable adsorbers/absorbers and filters, and combinations of the same. Therefore, the objective of these investigations was to identify and evaluate the characteristic impact of compounds in the exhaust air of these odor-emission sources. The volatile compounds were collected by using a microprocessor-controlled gas sampler through sorbent tubes of Tenax TA. The adsorbed compounds were analyzed by thermal desorption into a cryotrap and subsequent gas chromatography separation, followed by simultaneous olfactometry and mass spectrometry. In cooling gases of the coffee bean roasting numerous compounds (up to 100) were identified of which only 22 were important for the characteristic odor. These compounds were aldehydes (2-methyl propanal, 2- and 3-methyl butanal, 2-furancarboxyaldehyde, 5-methyl-2-furancarboxyaldehyde), diketones (2,3-butandione, 2,3-pentandione), pyrazines, pyridine, acetic acid, and furanmethanol. Other compounds with low concentrations but with a very low odor threshold and, therefore, important for the total odor were 3-methyl butanoic acid and guaiacol. Up to 50 compounds were identified in the exhaust air of fish meal production, the most significant of these being trimethylamine. Trimethylamine, with a very low odor threshold (0.0025 g/l air) and the highest content (up to 60% in the total ion chromatogram, more than 100 g/l) in the exhaust air of fish meal production, was responsible for the characteristic fishy odor. Beside trimethylamine only a few compounds, e.g., sulfides (dimethyl sulfide, dimethyl disulfide, dimethyl trisulfide), aldehydes (2-methyl propanal, 2- and 3-methyl butanal), ethanol, and guaiacol, played a secondary role for the total odor. In the exhaust air of the pig house up to 50 compounds were identified. Beside ammonia, the most important odor-active compounds were various carboxylic acids (acetic acid, butanoic acid, 3-methyl butanoic acid), sulfides (dimethyl sulfide, dimethyl disulfide, dimethyl trisulfide), trimethylamine, and the intensive odor-active p-cresol and 4-ethylphenol.     

食品工艺学实验教学的探索

分析了目前我校食品工艺学实验教学中的一些现状,并提出了今后在教学过程中的实践方案。着重要求学生在实验课中学会设计实验方案,掌握实验技能,从而提高学生分析问题和解决问题的能力。     

食品工艺学实验教学的探索

分析了目前我校食品工艺学实验教学中的一些现状，并提出了今后在教学过程中的实践方案。着重要求学生在实验课中学会设计实验方案，掌握实验技能，从而提高学生分析问题和解决问题的能力。     

Application of nanostructured lipid carrier in food for the improved bioavailability

Nanostructured lipid carriers (NLC) could be used as suitable carriers of water-insoluble nutrients such as coenzyme Q10 (CoQ10) improve their bioavailability. The CoQ10-NLC was prepared by high-pressure homogenization method. The freshly prepared CoQ10-NLC showed ellipsoid morphology under atomic force microscope, and the average encapsulation efficiency was about 98.4 ± 0.3%. Good physical and chemical stability was observed by photon correlation spectrum and HPLC, respectively. In 3 months’ storage, the concentration of CoQ10-NLC kept at 8.5 ± 1.5 mg/mL; the particle size was 190 ± 30 nm with polydispersity index (PDI) lower than 0.1. Lyophilization was proved feasible for the storage of NLC dispersion. The formulation also showed the potent possibility of application on beverage. Particle size remained relatively steady in simulated beverage solution for 3 months. The oral bioavailability study was carried out using Wistar rats. The relative bioavailability of CoQ-NLC was about 200% compared with CoQ10 suspension. In conclusion, the NLC formulation showed good stability and improved bioavailability. It demonstrated a promising perspective for daily consuming and industrial production.     

Selenium enriched spirulina and phycocyanin are sources of bioavailable selenium

Rats were fed for two weeks low-selenium semi-synthetic diet supplemented with different sources of selenium: sodium selenite (selenium concentration 96 and 350 mcg/kg diet), selenium-enriched Spirulina (selenium concentration 350 mcg/kg diet) and selenium-enriched Phycocyanin (selenium concentration 96 mcg/kg diet). Selenium bioavailability was evaluated in terms of selenium accumulation in blood and liver as well as glutathione peroxidase activity. It was shown that selenium from selenium-enriched Spirulina and selenium-enriched phycocyanin was high bioavailable in rats.