Effect of an organic and conventional rearing system on the mineral content of hen eggs

In this study, the effect on mineral content of eggs from organic and conventional-housing systems was investigated. For this, random samples of 12 eggs were collected in both housing systems. Egg shells and edible portions were analysed for ash, Ca, P, Mg, Fe, Zn and Cu contents.The P and Zn contents of the edible egg portion were lower in the organic eggs than in conventional eggs. Mg content of the eggshell was higher in organic eggs while Zn content showed a marked decrease. As far as Ca, Fe and Cu values were concerned, these did not differ between the eggs from organic and conventional systems.The results showed considerable differences in mineral content between the eggs from the hens reared in organic and conventional systems.     

Electron density maps of lysozyme calculated using synchrotron laue data comprising singles and deconvoluted multiples

We have used lysozyme as a test case to illustrate the application of a new method of estimating the intensities of Laue multiples reflection data in protein crystallography. Hen egg-white lysozyme, an enzyme with a single polypeptide chain of 129 amino acids, crystallizes in space group P4₃2₁2 with cell parametersa=b=79·1 Å,c=37·9 Å. Laue image plate data were collected using synchrotron radiation on station 9·5 at Daresbury with a total exposure time of 0·95 seconds. The data processed were separated into two data sets comprising the singles and the combined singles and deconvoluted multiples. The method of deconvolution was that of Campbell and Hao (1993), which utilizes the intensity variation of theλ-curve. Electron density maps (2F _o?F _c) based on the two data sets are then compared. This comparison shows that the deconvoluted multiples do indeed contribute usefully to the continuity of the maps due to the improved completeness of the data. A number of map sections along the polypeptide chain, based on the two Laue data sets, are shown for comparison. These include Arg 5, His 15, Phe 38, Asp 52, Tyr 53, Pro 70, Trp 108 and the four disulphide bridges.     

一维两阀：从《筑山庭造传》中辑考日本“江户造园新体图式”

长期以来,中日两国的造园理论体系被限定为一种“外师造化、中得心源”的产物,并将其视为是一种由“心”而生的艺术创造。江户时代之后,日本造园界将中国的“气象体志”理论发展总结为“技艺”“心”与“感”3个层次,后又总结成更为简化的神仙气、轮苑气、山林气、出世气、儒先气等俗理,并根据江户时代的赏析习惯,绘制出“真行草”47种规范化的造园图式,形成了“一维两阀”的造园现象,一跃成为研究日本古典造园艺术“图式”的学术途径与法门钥匙。基于对日本江户时期北村援琴的造园著作《筑山庭造传》的研究,将“美感”视作造园生发程式化设计的主要脉络,对日本“江户美感新体图式”的创新路径进行学术探讨,由此检验北村援琴所主张的内在渊源、理论谱系和路径谱系等问题,并以此充当研究中国造园文献之重要补遗。     

不同类型植物甾醇对蛋鸡脂类代谢的影响

旨在研究不同类型植物甾醇对蛋鸡脂类代谢的影响。选用72只30周龄伊莎褐蛋鸡,随机分为3组,每组8个重复,每重复3只。试验分组如下:(1)对照组,饲喂基础日粮;(2)天然植物甾醇组(NP),饲喂基础日粮+22.2 mg/kg天然植物甾醇(纯度为90%,植物甾醇净含量为20 mg/kg);(3)水溶性植物甾醇组(WP),饲喂基础日粮+50 mg/kg水溶性植物甾醇(纯度为40%,植物甾醇净含量为20 mg/kg)。试验为期8周。结果表明,添加2种植物甾醇使第4周血清三酰甘油(TG)、总胆固醇(TC)、高密度脂蛋白胆固醇(HDL-C)和低密度脂蛋白胆固醇(LDL-C)含量较对照组均有降低的趋势(P<0.1);WP组第4周脂蛋白脂酶(LPL)、肝脂酶(HL)和总酯酶(TL)活性较对照组有提高趋势,NP组血清HL活性也有提高的趋势(P<0.1),但在第8周各组均无显著差异;WP组第8周的蛋黄胆固醇含量显著低于NP组(P<0.05),而NP组与对照组差异不显著。本试验结果提示2种植物甾醇均有降低血脂和提高脂蛋白代谢酶活性的趋势,且此趋势随着时间的延长而逐渐消失,但对蛋黄胆固醇沉积无显著影响,只有WP在饲喂一段时间后有一定降低作用。     

5,6-Dihydro-2,4,6-trimethyl-4H-1,3,5-dithiazine – an aroma-active compound formed in course of the Likens–Nickerson extraction

 5,6-Dihydro-2,4,6-trimethyl-4H-1,3,5-dithiazine (thialdine) is an aroma-active compound that has been isolated from different species of meat. In this study we have investigated the formation of thialdine using the simultaneous distillation–extraction according to Likens–Nickerson for the extraction of aroma compounds. Three isomers of thialdine were identified in the aroma extract of cooked and dried hen meat. It was shown that these compounds are not genuine substances from the sample examined, but that they are artefacts formed during sample preparation. Received: 30 October 1996     

不同处理复合油菜籽对蛋鸡的营养价值评定

通过动物实验测定不同处理的复合油菜籽代谢能和营养物质的消化利用率,评定其对蛋鸡的营养价值。实验材料为破碎复合油菜籽、熟化复合油菜籽和膨化复合油菜籽。1)真代谢能法(TME)测定油菜籽代谢能与营养物质利用率:将64只30周龄、体重(3. 00±0.03) kg的海兰褐种公鸡,随机分为4组,分别强饲破碎复合油菜籽、熟化复合油菜籽、膨化复合油菜籽或绝食。2)氨基酸回肠消化率的测定:将48只25周龄、体重(2. 50±0. 02) kg的海兰褐蛋鸡,随机分成3组,分别饲喂纯合无氮饲粮、破碎复合油菜籽半纯合饲粮、膨化复合油菜籽半纯合饲粮。实验结果表明:1) TME法测定结果:熟化复合油菜籽和膨化复合油菜籽的TME值分别为14. 41、14. 59 MJ/kg;与破碎复合油菜籽相比,膨化复合油菜籽的粗脂肪和粗蛋白质表观利用率分别提高21. 79%和25. 22%(P 0. 01);除甘氨酸、组氨酸外,膨化复合油菜籽的氨基酸全肠道表观利用率和真利用率高于破碎复合油菜籽(P 0. 01)和熟化复合油菜籽(P 0. 05);熟化复合油菜籽大部分氨基酸全肠道利用率高于破碎复合油菜籽(P 0. 05)。2)氨基酸回肠消化率:与破碎复合油菜籽相比,膨化油菜籽的各氨基酸回肠表观消化率和回肠标准消化率得到了极显著的提高(P 0. 01),除了组氨酸外,膨化复合油菜籽各氨基酸回肠表观消化率、氨基酸回肠标准消化率都大于83%。复合油菜籽经加热处理尤其是135℃膨化后表观代谢能、粗脂肪、粗蛋白质、氨基酸利用率得到大幅度提高。     

Studies on chemically modified hen egg white and gelatin composites

Hen egg white (A) and gelatin (G) composites at different proportions were prepared and optimized by their stress–strain behavior. The optimized composite (AG) was graft copolymerised with methyl methacrylate (MMA). The AG and its graft copolymer AGMMA were characterized for their mechanical strength, water absorption capacity, Fourier transform infrared spectra, and circular dichroism (CD) spectroscopy. It was evident from the results that AGMMA possesses higher mechanical strength and lower water absorption capacity than does AG. The FTIR spectra of AG and AGMMA confirm the grafting phenomena of MMA onto AG, and the CD spectrum of AG shows two negative bands at around 207 and 222 nm and a positive band at around 191.76 nm, which confirms the α‐helix in the composite. The α‐helical structure in AG was broken and converted into unordered random coil in AGMMA because of the reaction conditions while grafting MMA onto AG, which was confirmed by the increase in mechanical strength of AGMMA. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 318–322, 2006     

Accelerated shelf-life testing of quality loss for a commercial hydrolysed hen egg white powder

In recent years, due to the specific health benefits associated with bioactive peptides and the reduction of protein allergenicity by enzymatic hydrolysis, the utilisation of protein hydrolysates in functional foods and beverages for both protein supplementation and clinical use has significantly increased. However, few studies have explored the moisture-induced effects on food protein hydrolysates, and the resulting changes in the structure and texture of the food matrix as well as the loss in functional properties of bioactive peptides during storage. The main purpose of this study is to determine the influence of water activity (a_w) on the storage quality of a commercial spray-dried hydrolysed hen egg white powder (HEW). During storage at 45 °C for two months at different a_ws (0.05–0.79), the selected physicochemical properties of the HEW samples were analysed. Overall, the effect of a_w on the colour change of HEW at 45 °C for one month was similar to that of HEW after four months at 23 °C due to the presence of a small amount of glucose in HEW. Several structural changes occurred at a_ws from 0.43 to 0.79 including agglomeration, stickiness and collapse. Kinetic analysis showed a first-order hyperbolic model fit for the change in the L^∗ value, the total colour difference (ΔE^∗) and the fluorescence intensity (FI). There was a high correlation between colour change and fluorescence, as expected for the Maillard reaction. The reduction in the remaining free amino groups was about 5% at a_w 0.50 and 6% at a_w 0.79 after one month storage. In summary, during storage, the Maillard reaction and/or its resulting products could decrease the nutritional value and the quality of HEW.