铁强化食盐的铁源筛选及稳定性研究

对铁强化食盐生产中不同铁剂对产品稳定性和品质的影响进行了研究。结果表明 ,以焦磷酸铁和乙二胺四乙酸铁钠为铁强化剂 ,稳定性较好 ,铁含量 (以铁元素计 )可达6 0 0mg/kg～ 12 0 0mg/kg ,颜色和口感不会明显改变。     

Growth and characterization of calcium pyrophosphate dihydrate grown in silica gel

Calcium pyrophosphate dihydrate crystals, which are responsible for various arthritic diseases, were grown in sodium metasilicate gel. Variations in gel density, pH value and concentration of the reactants were found to have profound effect on the growth of the crystals. The grown crystals were characterized using IR, XRD, TGA and optical microscopy.     

Suppression of Thermal Denaturation of Myosin Subfragment-1 of Alaska Pollack (Theragra chalcogramma) by Sorbitol and Accelerated Inactivation by Pyrophosphate

Thermal denaturation of myosin subfragment-1 (S-1), prepared from myofibrils (Mf) of Alaska pollack dorsal muscle by chymotryptic digestion, was well suppressed by sorbitol addition in a concentration dependent relationship. ATP and ADP also suppressed the ATPase inactivation significantly at different degrees. On the contrary, pyrophosphate (PPi) accelerated the inactivation by several-fold; half the maximal acceleration occurred at about 30 μn, M PPi concentration. The accelerated inactivation by PPi addition was remarkable at high-salt medium such as 0.5M KC1.     

电镀Sn-Ni合金在织物上的应用

采用已电镀铜的导电涤纶织物为基材,制备了枪黑色电磁屏蔽织物,并对其制备工艺及性能进行了初步的研究与探讨.利用正交试验方法研究了电流密度、时间、温度、pH、搅拌方式等工艺参数对Sn-Ni合金枪黑色镀层电阻及耐磨性能的影响,确定了较优的工艺条件:Jκ=0.8 A/dm2,t=15 min,θ=44℃,pH=8.6,阴极移动.实验表明,采用上述工艺制备的柔性电磁屏蔽材料具有良好的导电性能、耐磨性及附着力.     

焦磷酸盐镀铜工艺的改进

焦磷酸盐镀铜因具有镀液稳定、电流效率高、不含氰化物等优点而得到广泛应用.但是传统的镀液配方电流密度较小或含有机添加剂而导致镀液不稳定.通过在镀液中添加无机物来提高电流密度,讨论了无机添加物对电流密度的影响,给出了镀液配方及操作条件,提出了操作中应注意的问题.     

Effect of Tetrasodium Pyrophosphate on the Physicochemical Properties of Yogurt Gels

The effect of tetrasodium pyrophosphate (TSPP) on the properties of yogurt gels was investigated. Various concentrations (0.05 to 0.2%) of TSPP were added to preheated (85°C for 30 min) reconstituted skim milk, which was readjusted to pH 6.50. Milk was inoculated with 2% starter culture and incubated at 42°C until the pH reached 4.6. Acid-base buffering profiles of milk and total and soluble calcium levels were measured. Turbidity measurements were used to indicate changes in casein dispersion. Storage modulus (G′) and loss tangent (LT) values of yogurts were monitored during fermentation using dynamic oscillatory rheology. Large deformation properties of gels were also measured. Microstructural properties of yogurt were observed using fluorescence microscopy. The addition of TSPP resulted in the disappearance of the buffering peak during acid titration at pH ∼5.1 that is due to the solubilization of colloidal calcium phosphate (CCP), and a new peak was observed at lower pH values (pH 4.0-4.5). The buffering peak at pH 6.0 during base titration virtually disappeared with addition of TSPP and a new peak appeared at pH ∼4.8. The addition of TSPP reduced the soluble Ca content of milk and increased casein-bound Ca values. The addition of up to 0.125% TSPP resulted in a reduction in turbidity because of micelle dispersion but at 0.15%, turbidity increased and these samples exhibited a time-dependent increase in turbidity because of aggregation of casein particles. Gels made with 0.20% TSPP were very weak and had a very high gelation pH (6.35), probably due to complete dispersion of the micelle structure in this sample. The LT value of gels at pH 5.1 decreased with an increase in TSPP concentration, probably due to the loss of CCP with the addition of TSPP. The G′ values at pH 4.6 of gels made with ≤0.10% TSPP were not significantly different but the addition of ≥0.125% TSPP significantly decreased G′ values. The addition of 0.05 to 0.125% TSPP to milk resulted in a reduction in the yield stress values of yogurt compared with yogurt made without TSPP. Greater TSPP levels (>0.125%) markedly reduced the yield stress values of yogurt. Lowest whey separation levels were observed in yogurts made with 0.10% TSPP. High TSPP levels (>0.10%) greatly increased the apparent pore size of gels. Addition of very low levels of TSPP to milk for yogurt manufacture may be useful in reducing the whey separation defect, but at TSPP concentrations ≥0.125% very weak gels were formed.     

不同pH对焦磷酸铵水解的影响

以主成分为焦磷酸铵的水溶性聚磷酸铵为实验原料,设置8.2、6.0、4.0、3.5、3.0、2.5、2.0等7组pH梯度,系统研究了酸度对焦磷酸铵水解的影响。结合一级反应动力学方程与阿累尼乌斯方程进行焦磷酸铵的水解动力学计算,结果表明：经过310 d（第二批260 d）的放置,pH从8.2降低到2.0时焦磷酸铵质量分数从初始态的92.6%依次减少为85.4%、51.2%、50.6%、50.2%、24.3%、12.9%和6.0%。焦磷酸铵在自然温度下的水解速率随着pH的降低而不同程度地加快,服从一级反应机理。pH从8.2降低到2.0时焦磷酸铵的水解速率常数从2.92×10-4~3.43×10-4增加至3.41×10-3~1.47×10-2,二者相差10~40余倍,对应半衰期为50~2 000 d。秋冬与春夏两时段的水解速率差异很大,二者水解速率常数相差1.17~4.32倍,焦磷酸铵的水解活化能为7.5~68.5 kJ/mol。     

国产电镀黄铜生产线技术研发

介绍国产电镀黄铜生产线技术研发现状,给出工艺流程和生产线工艺参数。生产线长度260～280 m,年生产能力1万～1.5万t,可同时处理42～56根直径0.76～3.2 mm钢丝。采用明火加热炉,Dv值可达80 mm.m/min。采用水浴索氏体化处理,焦磷酸盐电镀铜,硫酸盐电镀锌,感应加热热扩散,得到铜质量分数67.0%左右的高铜黄铜镀层,产品完全满足帘线钢丝的拉拔要求和钢帘线与橡胶的黏结力要求。     

三种添加剂在鱼肉猪肉复合凝胶中的作用

为了改善鱼肉/猪肉复合肉糜（配比分别为3：7和7：3）的凝胶性能,研究了添加剂（TGase、CaCl2和焦磷酸钠）对鱼肉/猪肉复合凝胶的作用效果。结果表明,两种复合肉糜凝胶的破断强度、凝胶强度和保水性均随着TGase添加量的增加而增大,对鱼肉/猪肉（7：3）复合凝胶的增强作用更显著,而且降低了鱼肉/猪肉（7：3）复合凝胶的白度。CaCl2的添加也可增大复合肉糜的凝胶强度和白度,但高剂量的CaCl2（〉10mmol/kg）会降低其保水性。鱼肉/猪肉为7：3和3：7复合凝胶的凝胶强度分别于焦磷酸钠为0.05%和0.3%时达到最大值,高剂量的焦磷酸钠（〉0.3%）会提高复合凝胶的持水性,而对白度的影响较小。     

Steel slag waste combined with melamine pyrophosphate as a flame retardant for rigid polyurethane foams

To explore the potential application of industrial waste, steel slag powder in combination with melamine pyrophosphate (MPP) was adopted to improve the flame retardancy of rigid polyurethane foam (RPUF). The incorporation of steel slag slightly reduced the thermal conductivity of the resulting flame-retardant RPUF samples. The addition of MPP and/or steel slag did not significantly alter the thermal stability in terms of T_-10% and T_max but did obviously increase the T_-50% value, suggesting the improved thermal resistance of the residues. The coaddition of MPP and steel slag into RPUF resulted in higher LOI values and lower peak heat release rates than the samples incorporating either MPP or steel slag alone. The superior flame retardancy could be attributed to MPP promoting char formation, which then acted as a barrier at the beginning of RPUF thermal decomposition; simultaneously, the thermally stable inorganics in the steel slag powder strengthened the thermal resistance of this char layer.