Perfluorinated contaminants in fur seal pups and penguin eggs from South Shetland, Antarctica

Perfluorinated compounds (PFCs) have emerged as a new class of global environmental pollutants. In this study, the presence of perfluorochemicals (PFCs) in penguin eggs and Antarctic fur seals was reported for the first time. Tissue samples from Antarctic fur seal pups and penguin eggs were collected during the 2003/04 breeding season. Ten PFC contaminants were determined in seal and penguin samples. The PFC concentrations in seal liver were in the decreasing order, PFOS > PFNA > PFHpA > PFUnDA while in Adélie penguin eggs were PFHpA > PFUnDA > PFDA > PFDoDA, and in Gentoo penguin eggs were PFUnDA > PFOS > PFDoDA > PFHpA. The PFC concentrations differed significantly between seals and penguins (p < 0.005) and a species-specific difference was found between the two species of penguins (p < 0.005). In our study we found a mean concentration of PFOS in seal muscle and liver samples of 1.3 ng/g and 9.4 ng/g wet wt, respectively, and a mean concentration in Gentoo and Adélie penguin eggs of 0.3 ng/g and 0.38 ng/g wet wt, respectively. PFCs detected in penguin eggs and seal pups suggested oviparous and viviparous transfer of PFOS to eggs and off-springs.     

Egg yolk conjugated linoleic acid alters phospholipid molecular species in chick tissues

The effects of egg conjugated linoleic acid (CLA) on chick yolk sac and liver phospholipid composition and molecular species were determined. Fertile eggs with no (control), low (CLA1) or high (CLA2) levels of CLA were incubated. Upon hatching, total lipid in the remnant yolk sac constituted 11.5, 18.9 and 15.3% in control, CLA1 and CLA2, respectively (p <0.05). Maternal CLA led to a decrease in phosphatidylcholine (PtdCho) and phosphatidylethanolamine (PtdEtn) and an increase in lysophosphatidylcholine (LPtdCho) in the yolk sac and liver tissues of CLA1 and CLA2 when compared to control (p <0.05). The effect of maternal dietary CLA was very prominent in yolk sac PtdCho (34:1) where 13 and 38% reductions were observed in CLA1 and CLA2, respectively, when compared to control. Among different liver PtdCho species, the highest difference was found in 36:2, where a 41% increase was observed in CLA2 when compared with control chicks. The liver LPtdCho of CLA1 and CLA2 chicks had a 92% increase in 16:0 and 18:0 when compared to control. Over 80% increase was observed for 18:2 and 20:4 in the liver LPtdCho of CLA2 chicks compared to control. These results suggest that the yolk CLA content alters the proportions of phospholipids in the progeny during avian embryogenesis.     

Bio-sorption for tannery effluent treatment using eggshell wastes; kinetics,isotherm and thermodynamic study

Since, cobalt, zinc, mercury and lead ions are high toxic heavy metals; this work aims to investigate the efficiency of eggshell as a low cost sorbent for their ions from aqueous solution. Adsorption of heavy metals on surfaces of eggshell obeyed second order kinetics. Adsorption isotherm belonged to Freundlich model and displayed multilayer adsorption. The maximum adsorption capacity was estimated as 204, 153, 121 and 98 mg/g for Co³⁺, Zn²⁺, Hg²⁺ and Pb²⁺ respectively. The values of free energy of adsorption evidenced the physical adsorption occurrence. It is demonstrated that eggshell, as an industrial waste, was efficiently used as an adsorbent for wastewater treatment. Eggshells powder removed efficiently heavy metal ions from a tannery wastewater and removal efficiency reached up to 99%.     

A comparative study of heat and high pressure induced gels of whey and egg albumen proteins and their binary mixtures

Large deformation rheological studies of either egg albumen or whey protein isolate (15% protein w/w) gels induced by heating at 90 °C for 30 min were compared to those induced by a range high pressures (400–800 MPa for 20 min). Gels made by heating indicated higher gel strength and Young's modulus values for whey protein from pressures of 400–600 MPa for 20 min but similar values at 650–800 MPa. In contrast, egg albumen showed no gelation below 500 MPa for 20 min, but there was an increase in both gel strength and Young's modulus with increasing pressure, although values remained lower than those of the heat-induced gels. A mixture of 10:5 whey/egg albumen showed the highest gel strength and Young's modulus for both heated and high pressure-treated (400–600 MPa) gels, although, the heated mixture had the highest values. Electron micrographs indicated that high pressure-treated gels had a porous aggregated network for egg albumen while whey proteins showed a continuous fine stranded network. The heated mixtures of whey:egg albumen (7.5:7.5) showed large dense aggregates whereas high pressure-treated mixtures produced smaller aggregates. Raman spectroscopy of both heated and high pressure-treated whey and egg albumen (15% w/w in D₂O pD7) and their binary mixtures (7.5:7.5, protein w/w) indicated changes in β-sheet structures in the Amide 111′ region (980–990 cm⁻¹); however, peak intensity was reduced for high pressure-treated samples. β-Sheet structure (1238–1240 cm⁻¹) present in heated whey was absent in high pressure-treated whey and in egg albumen. Involvement of hydrophobic regions was reflected by changes in the CH (1350 cm⁻¹) and CH₂ (1450 cm⁻¹) bending vibrations. In addition to the Trp residues at 760 cm⁻¹, there were broad peaks at 874–880 cm⁻¹ and tyrosine 1207 cm⁻¹ in the high pressure-treated samples. Disulphide bands (500–540 cm⁻¹) in heated whey and egg albumen proteins showed higher peak intensities compared to high pressure-treated samples. Differences in the experimental and theoretical spectra indicated changes in the hydrophobic regions, tyrosine (1207 cm⁻¹) and tryptophan (880 cm⁻¹) and CH₂ bending in high pressure-treated samples, whereas heated samples indicated marked changes in β-sheet structures (987 and 1238 cm⁻¹) as well as hydrophobic regions CH (1350 cm⁻¹) and CH₂ (1450 cm⁻¹) bending vibrations.     

涂膜保鲜对不同蛋龄鸡蛋贮藏品质的影响

选用0,3,6,10 d蛋龄鸡蛋,经涂膜处理,对比不同蛋龄组贮藏品质的变化.结果表明：各组鸡蛋失重率差异不显著（P＞0.05）;蛋黄系数差异显著（P＜0.05）;蛋白系数和蛋白pH值差异极显著（P＜0.01）.贮存60,0 d蛋龄全部为新鲜蛋,失重率1.95%,蛋黄系数为0.32,蛋白系数为0.61,蛋白pH值仅为8.79;3 d蛋龄次鲜蛋占84%,散黄蛋占16%;6 d蛋龄次鲜蛋占50%,散黄蛋占50%;10 d蛋龄全部散黄.     

Flow injection chemiluminescence determination of femtogram-level cobalt in egg yolk,fish tissue and human serum

Femtogram-level cobalt was determined based on its significantly catalyzed effect on luminol-dissolved oxygen chemiluminescence (CL) reaction in the flow system. The increment of CL signal was proportional to the concentration of cobalt, giving linear range from 10 fg ml⁻¹ to 50 pg ml⁻¹ (r² = 0.9992) with a detection limit 4 fg ml⁻¹ (3σ). At a flow rate of 2.0 ml min⁻¹, a typical analytical procedure for cobalt, including sampling and washing, could be performed in 0.5 min with a relative standard deviation of less than 3.0%. The proposed method has been successfully applied for the determination of cobalt in egg yolk, fish tissue and human serum, agreed well with radioimmunoassay.     

鸡蛋清粉制品残存抗生物素蛋白(Avidin)的分离和分析

对市售冲饮用的鸡蛋清粉中残存的抗生物素蛋白进行了分离和鉴定,结果表明鸡蛋清粉中仍具有一定比活性10U/mg)的抗生物素蛋白,含量达0．040~0．055 mg/g。     

酵母发酵法脱除蛋清中葡萄糖的研究

脱糖处理是干燥蛋白制品加工中的必要步骤，本文探讨了面包酵母发酵法对蛋清进行脱糖的工艺，并进一步比较了脱糖前后蛋清的性质。采用了酶一比色法精确测定葡萄糖含量，并研究了时间、pH、温度等参数对脱糖率的影响，确定了脱糖的优化工艺条件：添加0．2％即发干酵母，温度30℃，pH5．5，发酵3．5-4．5hr，脱糖率可达95％以上。脱糖后的蛋清具有更好的凝胶和起泡性质及更低的粘度。     

Adsorption of egg yolk plasma cholesterol using a hydrophobic adsorbent

Data on hydrophobic adsorption equilibrium of egg yolk plasma cholesterol were obtained using Streamline Phenyl^® resin in batch suspension at room temperature (25 °C). Influence of two types of salt (NaCl and Na₂SO₄) at four concentrations (0.0; 0.05; 0.1, and 0.2 M) on equilibrium was analyzed. Increased salt concentration reduced the amount of cholesterol adsorbed in the resin. Two isotherm models (Langmuir and a modified model based on type S-isotherm) were used to represent solid-liquid equilibrium data. The latter led to a better fit of the equilibrium data, with a 99.8% value of RSSE. A 70% reduction of the cholesterol content in the plasma was obtained with a 1:4 plasma:water dilution ratio.     

食品加工对蛋清致敏性的影响研究进展

摘要：鸡蛋是人们日常生活中不可或缺的营养品，然而，鸡蛋也是最常见的引起过敏反应的食物之一。婴儿和儿童是鸡蛋过敏的高发人群，鸡蛋过敏反应主要是由血清免疫球蛋白E（IgE）介导的，引发皮肤、消化道、呼吸道相关的症状，甚至可导致危及生命的严重过敏反应。鸡蛋过敏目前尚无特效治愈方法，患者严格避免摄入鸡蛋成分被认为是最有效的预防手段，但严格避食会影响患者的生活质量和膳食营养，且因意外摄入鸡蛋过敏原导致过敏症状出现的情况屡屡发生。可见在鸡蛋过敏的应对方面，迫切需要新的有效方法。食品加工技术作为从鸡蛋致敏的源头上控制过敏反应的方法，近年来发展迅速。本文综述了各种常见食品加工方法对蛋清致敏性的影响，为后续开发低致敏鸡蛋产品提供思路。