Improvement of the material property of shark type I collagen by composing with pig type I collagen

Fibril reconstruction process, that is, the nucleation and growth of mixed type I collagen fibril of shark and pig, progressed faster than that of the individual collagen species of shark or pig. The reconstructed mixed collagen fibril had a greater resistance to return to the solution or to melt into gelatin in comparison with the counterpart consisting solely of shark collagen. The denaturation temperature of the mixed collagen gel was about 10 degrees C higher than that of shark, and about 5 degrees C lower than that of pig. By scanning electron microscopy, the diameter of mixed collagen fibril showed an intermediate range between shark and pig collagen fibril. The breaking strength of the mixed collagen gel was tougher than that of pig, but weaker than that of shark. Other physicochemical properties of the mixed type I collagen gel were observed to be at intermediate positions between those of shark and pig type I collagen gels.     

植物单宁酸交联明胶的条件优化及性质分析

该文用单宁酸作交联剂对明胶进行交联改性,通过响应面法优化反应条件并建立回归模型,并对交联前后的明胶进行十二烷基磺酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)、紫外光谱和黏度等3方面的分析测定,确认单宁酸交联对明胶所产生的交联作用,开发新食品配料交联明胶。结果显示:适宜的交联反应条件为反应温度47.5℃,时间50h,单宁酸添加量80mg/g明胶。性质分析表明,与原料明胶相比交联明胶一些性质发生变化,紫外光谱分析发现交联明胶在276nm出现新吸收峰,表明交联明胶分子中存在苯环;电泳后交联明胶的蛋白质条带色泽明显变浅,且交联度越大条带色泽越浅,此外,交联明胶溶液的黏度明显增大,说明单宁酸交联处理使交联明胶中有更多的大分子物质生成。     

脱水热处理改善鱼皮明胶可食膜的性能

为了改良鱼皮明胶可食膜的性能,拓宽可食膜的资源,以罗非鱼皮为原料提取明胶制备可食膜,考察了脱水热处理对其理化性质的影响。结果发现罗非鱼皮明胶中亚氨基酸含量为19.3%,主要由β链和α链组成,制备的可食膜其抗拉伸强度（tensile strength,TS）达37.5 MPa。80℃热处理对明胶膜的理化性质无明显的影响。当热处理温度提高到100℃或120℃时,伴随热处理明胶膜的TS逐渐增大而溶解性逐渐降低。在热处理过程中,膜的颜色略微变黄,但断裂延伸率和透明度却无明显的变化。SDS-PAGE 图谱和明胶膜在蛋白变性剂中的溶解性结果显示,高于100℃的热处理使明胶α链和β链发生交联,增强疏水相互作用和共价键在明胶膜中的贡献,使膜的玻璃化转变温度得到提高。以上结果表明,脱水热处理可改善鱼皮明胶膜的机械性能、耐水性能和热稳定性,有利于拓宽可食膜的资源和鱼皮明胶膜的应用。     

Physical and mechanical properties of washed sediment mixed with organic matter

Soil from cleaning and washing of sugar beet during processing is collected and decanted in tanks each year over a period of several months. Instead of spreading it on agricultural land, another option is to reuse the sediment for crop growth. The physical and mechanical properties of the non-structured washed soil (WS) and the efficiency of added organic matter (peat and green waste compost) were evaluated by comparison with an arable silt loam soil (AS). Water retention data were expressed in a double-exponential function which characterized soil structural and matrix pore space. The effects on saturated hydraulic conductivity and pore space morphology from applying loads of 60 and 200 kPa on two initial volumetric water contents (12 and 25%) were investigated using image analysis. WS was a silt loam with no plasticity, and its void ratio and water retention were higher than the AS before compression. However, WS had a very small amount of structural pore space and despite its higher void ratio, its hydraulic conductivity was always lower than AS after compression. Organic matter improved all the WS properties by increasing structural porosity and vertical stress resistance. Organic matter created elongated and tortuous pores and increased K _s values by changing pore size distribution. During compression large pores with a radius >1500 μm disappeared in WS mixtures but were still observed in AS and were maintained by aggregate stability.     

Aggregate characterization as compared to soil bulk properties

The aim of this paper is to clarify the effect of soil aggregation on the physical and chemical properties of structured soils and as compared with the homogenized material. Aggregation and aggregate strength do not only depend on biological activity and organic exudates, but also on the intensity, number and time of swelling, and drying events. Such aggregates are not only more dense than the structured bulk soil, the intra-aggregate pore distribution consists not only of finer pores, but they are also more tortuous. Thus, water and ion fluxes by mass flow as well as ion transportation by diffusion are delayed, whereby the length of the flow path in such tortuous finer pores further retards chemical exchange processes. Futhermore, the chemical composition of the percolating soil solution differs more from that of the corresponding homogenized material the stronger and denser the aggregates are. From the mechanical point of view, the strength of single aggregates, determined as the angle of internal friction and cohesion, depends on the number of contact points or the forces, which can be transmitted at each single contact point. However, internal soil parameters, like grain size distribution or chemical composition, further affect the strength. The more structured the soils are, the higher is the proportion of the effective stress on total stress, but even in single aggregates neutral stresses can be revealed. This is true because of the relationship to the smaller value of the hydraulic conductivity and higher tortuosity. Finally, some dynamic effects on aggregation and aggregate deterioration are discussed.     

Physical properties of soils in Rostov agglomeration

Physical properties of natural and anthropogenically transformed soils of Rostov agglomeration were examined. The data obtained by conventional methods and new approaches to the study of soil physical properties (in particular, tomographic study of soil monoliths) were used for comparing the soils of different functional zones of the urban area. For urban territories in the steppe zone, a comparison of humus-accumulative horizons (А, Asod, Ap, and buried [A] horizons) made it possible to trace tendencies of changes in surface soils under different anthropogenic impacts and in the buried and sealed soils. The microtomographic study demonstrated differences in the bulk density and aggregation of urban soils from different functional zones. The A horizon in the forest-park zone is characterized by good aggregation and high porosity, whereas buried humus-accumulative horizons of anthropogenically transformed soils are characterized by poor aggregation and low porosity. The traditional parameters of soil structure and texture also proved to be informative for the identification of urban pedogenesis.     

Antioxidant properties of a radical-scavenging peptide purified from enzymatically prepared fish skin gelatin hydrolysate

Hoki (Johnius belengerii) skin gelatin was hydrolyzed with three commercial enzymes to identify radical-scavenging potencies of derived peptides. Peptides derived from tryptic hydrolysate exhibited the highest scavenging activities on superoxide, carbon-centered 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals assessed by ESR spectroscopy. Following consecutive chromatographic separations of tryptic hydroolysate, the peptide sequence His-Gly-Pro-Leu-Gly-Pro-Leu (797 Da) acted as a strong radical scavenger under studied conditions. Further, this peptide could act as an antioxidant against linoleic acid peroxidation and the activity was closer to the highly active synthetic antioxidant butylated hydroxytoluene (BHT). In addition, antioxidative enzyme levels in cultured human hepatoma cells were increased in the presence of this peptide and it was presumed to be the peptide involved in maintaining the redox balance in the cell environment. Present data indicate that free-radical-scavenging activities of hoki skin gelatin peptides substantially contribute to their antioxidant properties measured in different oxidative systems.     

Physical properties of homoionic montmorillonite and kaolinite complexed with amino acids and peptides

X-ray diffractometry was used to investigate whether various amino acids and peptides expanded montmorillonite (M) homoionic to different cations, and the electrophoretic mobility (EPM) was measured to determine whether the binding of these amino acids and peptides influenced the net surface charge of M and kaolinite (K). Neither aspartic acid, adsorbed at equilibrium at concentrations of 20–250 nM mg^?1 M homoionic to Ca or Zn, nor cysteine, at 50–830 nM mg^?1 M homoionic to Zn or Al, caused expansion, whereas proline, at 90–870 nM mg^?1 clay, caused expansion of M homoionic to Ca or Zn, and both proline and arginine, at 60–1150 nM mg^?1 clay, caused expansion of M homoionic to H or Al. The extent of expansion caused by proline and arginine was related to the concentration of the amino acids and the exchangeable cation on the homoionic M. Only M-A1 complexed with arginine remained expanded after extensive washing of the clay-amino acid complexes. The expansion of M was apparently dependent on both the type of exchangeable cation on the clay and the characteristics of the amino acid (i.e. the functional groups, dielectric constant increment, dipole moment and concentration). M homoionic to H, Na, Zn, Al or La was not expanded by a series of di- to tetrapeptides bound on these clays and none of the homoionic K-amino acid or peptide complexes was expanded. The EPM of the homoionic M and K and of the corresponding clay-amino acid or peptide complexes was identical, indicating that the concentration of the amino acids or peptides bound was not sufficient to cover enough of the surface of the clays to alter significantly their net charge. The lack of differences in the bulk pH of the clays after binding with amino acids or peptides (with the exception of complexes with arginine) also indicated limited coverage of the clays by these organics.     

牡丹花红色素理化性质研究

目前牡丹主要是用于观赏,其综合加工技术没有突破。为了为牡丹花保鲜、护色和色素加工提供理论支持,该文对从牡丹红色品种洛阳红中提取的牡丹红色素进行理化性质研究。结果显示:牡丹红色素水溶性好,颜色随pH值变化而变化。pH值小于3时比较稳定,最大吸收波长为526.5 nm。在酸性条件下该色素对光、热有很好的稳定性;耐氧化性和还原性较差;Zn²⁺、Mg²⁺、Fe²⁺、K⁺、Cu²⁺、Ca²⁺离子对牡丹花红色素的稳定性影响不大,但Sn²⁺、Fe³⁺离子可使色素溶液变色,稳定性差。     

Physical properties of some intensively cultivated soils of Ireland amended with spent mushroom compost

In this paper, spent mushroom compost (SMC), a by‐product of the mushroom industry, is proposed as a suitable organic amendment for soil structure restoration. A 4‐month incubation pot trial was conducted in which fresh and composted SMC was amended at three different rates (50, 100 and 200 t ha⁻¹) to a range of structurally degraded tillage soils (n = 10). Soil OC content and aggregate stability as determined by the three disrupting tests of the Le Bissonnais method (fast‐wetting, slow‐wetting and mechanical breakdown) were investigated. Applications of 50, 100 and 200 t ha⁻¹ fresh SMC increased the OC content by 2·71 per cent, 2·69 per cent and 2·49 per cent respectively, while amendments of composted SMC increased the OC content by 3·28 per cent, 2·94 per cent and 2·87 per cent for each application rate, respectively. The effect of SMC on aggregate stability was generally positive and statistically significant in most soils. However, in soils 3 and 4 an application rate of 200 t ha⁻¹ SMC decreased the aggregate stability, on average, by 15 per cent, in comparison to the control, for the fast‐wetting test. Aggregate stability was strongly controlled by the inherent OC content of the study soils; that is, the OC content prior to SMC addition. A positive correlation coefficient was also evident for the dithionite‐extractable iron, most pronounced for slow‐wetting and mechanical breakdown treatments (r = 0·844 and r = 0·817 respectively). It is clear from this research that SMC amendments have the capacity to improve soil structural stability. Copyright © 2007 John Wiley & Sons, Ltd.     

微波真空干燥扇贝柱的物理和感观特性研究

微波真空干燥是一项新兴食品干燥技术。进行了扇贝柱的微波真空干燥试验，研究了微波真空干燥参数对扇贝柱物理和感观特性的影响规律，并与传统的自然干燥和热风干燥进行了对比分析。结果表明，不同微波功率和真空度组合对扇贝柱的物理和感观特性有明显影响，在微波功率和真空度为3 W/g和0.090 MPa时，干燥扇贝柱具有良好的色泽及表面质量，仅需30 min即可达到20%湿基含水率，收缩率和复水率与自然干燥扇贝柱相近；减小微波功率和降低真空度至2 W/g和0.074 MPa时，干燥扇贝柱的收缩率会增加、色泽和表面质量会变差。试验结果还表明，各种参数组合条件下的微波真空干燥扇贝柱，其干燥速度和抗破碎能力均明显优于自然干燥及热风干燥。利用微波真空干燥扇贝柱，对提高干燥速度和改善产品品质具有明显优势。     

Physical and sensory properties of dairy products from cows with various milk fatty acid compositions

Dairy products from milk of cows fed diets rich in polyunsaturated fatty acids have a more health-promoting fatty acid composition and are softer but often have oxidized flavors. Dairy products made from cow's milk that has more- or less-unsaturated fatty acid compositions were tested for differences in texture and flavor from those made from bulk-tank milk. The milk was manufactured into butter, vanilla ice cream, yogurt, Provolone cheese, and Cheddar cheese. The products were analyzed for fatty acid composition, physical properties, and flavor. Milk of cows with a more monounsaturated fatty acid composition yielded products with a more monounsaturated fatty acid composition that were softer and had a satisfactory flavor. Thus, selection of cows for milk fatty acid composition can be used to produce dairy products that are probably more healthful and have a softer texture.     

北方垄作萝卜物理力学特性

通过北方垄作栽培收获期青萝卜和红萝卜的田间和实验室测定,探寻其几何参数、松土位置参数优化组合及拔取力等物理力学特性。采用数理统计方法对收获期萝卜的几何特性进行分析,得出了两种萝卜主要几何特性指标值的变化区间和分布频率;通过拉伸试验对收获期萝卜根茎结合部抗拉强度、拔取力等力学特性进行测试,应用软件Design - Expert Version 6.0.10分析,得出了青萝卜和红萝卜根茎结合部抗拉强度分别为(2.45±1.23)105 Pa和(2.17±1.08)105 Pa,最小抗拉力分别为90 N和110 N,土壤自然状态下所需拔取力分别为(191±113.8)N和(197±107.2)N,部分萝卜会发生枝断漏收现象;采取松土拔取收获方式,当一侧松土位置参数优化组合为松土深度15～26 cm、松土距离10～20 cm时,青萝卜所需拔取力小于90 N,当一侧松土位置参数优化组合为松土深度18～24 cm、松土距离12～16 cm时,红萝卜所需拔取力小于110 N,不会发生拔断漏收现象。为拔取式萝卜收获机的设计提供理论依据。     

Physical properties of peat soils under different land use options

Pristine peat soils are characterized by large porosity, low density and large water and organic matter contents. Drainage and management practices change peat properties by oxidation, compaction and mineral matter additions. This study examined differences in physical properties (hydraulic conductivity, water retention curve, bulk density, porosity, von Post degree of decomposition) in soil profiles of two peatland forests, a cultivated peatland, a peat extraction area and two pristine mires originally within the same peatland area. Soil hydraulic conductivity of the drained sites (median hydraulic conductivities: 3.3 × 10^?5 m/s, 2.9 × 10^?8 m/s and 8.5 × 10^?8 m/s for the forests, the cultivated site and the peat extraction area, respectively) was predicted better by land use option than by soil physical parameters. Detailed physical measurements were accompanied by monitoring of the water levels between drains. The model ‘DRAINMOD’ was used to assess the hydrology and the rapid fluctuations seen in groundwater depths. Hydraulic conductivity values needed to match the simulation of observed depth to groundwater data were an order of magnitude greater than those determined in field measurements, suggesting that macropore flow was an important pathway at the study sites. The rapid response of depth to groundwater during rainfall events indicated a small effective porosity and this was supported by the small measured values of drainable porosity. This study highlighted the potential role of land use and macropore flow in controlling water table fluctuation and related processes in peat soils.     

Physical properties of soddy-podzolic soils in a long-term field experiment

The main physical properties of soddy-podzolic soils in a long-term field experiment have been studied. It is shown that their changes under the impact of a century-long application of lime, fertilizers, and manure have been relatively small. Reliable differences in the parameters of approximation of the dependence of penetration resistance on the soil water content in the variant with regular application of organic fertilizers have been revealed. This attests to stronger interparticle bonds (within the studied moisture range) in this variant. Interparticle bonds in the control variant and in the variant with lime application tend to increase with a decrease in the soil water content more significantly than those in other experimental variants. This may be due to the coarser texture of the soil in the control variant and to the aggregation of soil particles under the impact of lime in the variant with lime application.     

Physical properties and moisture retention characteristics of some nigerian soils

Measurements were made of physical characteristics of 119 samples from 23 profiles derived from two parent materials in Nigeria. The laboratory analyses included texture, plasticity and shrinkage characteristics, and a range of soil moisture constants including saturation point and moisture retention at various suctions. Simple and multiple correlation coefficients and regression analyses were conducted to investigate the possibilities of obtaining estimates of soil moisture retention from the textural analysis. Clay and sand contents are correlated with various soil moisture constants. The textural analysis may therefore be used to estimate moisture holding capacity at different suctions for these and similar soils with a predominantly uniform clay mineralogy, dominated by kaolinite and sesquioxides. Moisture retention curves indicate that the “field capacity” for most of these soils is better estimated at 60 or 100 cm of water suction rather than at 0.3 bar. A plot of the pF curves indicated only slight differences between moisture retention at 2 or 3 bar suction and at 15 bar suction.     

肉桂油/海藻酸钠薄膜物理特性和抗菌性能分析

为了研究开发新型可降解抗菌包装材料,该文以添加不同体积肉桂油到海藻酸钠膜液中制成的肉桂油/海藻酸钠抗菌薄膜为研究对象,比较分析肉桂油添加量对肉桂油/海藻酸钠薄膜厚度、透光率、色泽和水蒸气透过率等物理特性的影响,同时,考察其对薄膜的抗菌性能的影响。膜液中肉桂油体积分数在0～1.0%时,薄膜厚度无明显变化,体积分数为1.2%时,薄膜厚度显著增加。随着肉桂油体积分数的增加,薄膜的透光率显著降低,薄膜水蒸气透过系数增大。肉桂油对薄膜色泽影响显著,随着肉桂油添加量的增加,薄膜色泽值a和b呈显著增加趋势。膜液中肉桂油体积分数为0.8%时,薄膜抗菌能力显著增强。研究结果表明,当膜液中肉桂油体积分数为0.8%时,薄膜具有较好的抗菌效果和物理性能。该研究可为肉桂油/海藻酸钠可降解抗菌薄膜生产工艺参数的进一步优化提供参考。