高压粉末制样-X射线荧光光谱法测定海洋沉积物中28种组分

常规粉末压片制样是一种简单、高效的绿色环保制样技术,但是应用于某些沉积物样品制备存在样片表面粗糙和粉末容易脱落的问题。实验采用高于常规的压力进行样品制备,建立了X射线荧光光谱法(XRF)分析海洋沉积物样品中包括硫、氧化钠、氧化镁、三氧化二铝、二氧化硅、五氧化二磷、氧化钾、氧化钙、二氧化钛、氧化锰、三氧化二铁、钴、镍、铜、锌、钒、铬、镓、铌、锆、钇、锶、铷、铅、钡、镧、钕和铪在内的28种主、微量组分的方法。探讨了压力为300 kN和1 600 kN时的制样效果,并尝试引入BP神经网络模型利用其非线性拟合能力校正主量组分的基体效应。结果表明,采用1 600 kN压力制备的样片,表面致密、光滑、不龟裂和不掉粉,制样重复性和测试精密度也有较大提高。以55个有证标准物质中17种组分的数据集为训练样本,建立了海洋沉积物样品中主、微量组分的遗传算法-BP神经网络预测模型。按照实验方法对各组分含量相对较低的实际样品连续测试12次,计算得方法的检出限在 0.63～634 μg/g之间;精密度试验结果表明,各组分测定值的相对标准偏差(RSD, n=7)为0.16%～25.1%。方法用于海洋沉积物实际样品分析,其分析结果与国标法的测定结果吻合,能够满足海洋沉积物样品中多种组分准确分析的要求。     

In vitro gas production profiles and fermentation end‐products in processed peas,lupins and faba beans

BACKGROUND: An experiment was carried out to establish whether using a pre‐compacting device (expander) changes the contribution of dry matter (DM) and degradative behaviour of peas, lupins and faba beans over the different fractions (non‐washable fraction, NWF; insoluble washable fraction, ISWF; soluble washable fraction, SWF). Samples of the entire concentrate ingredients (WHO ingredients) and their different fractions (NWF, ISWF and SWF) were subjected to three processes (Retsch milling, R; expander treatment, E; expander‐pelleting, EP) and their fermentation characteristics were evaluated using an in vitro gas production technique. RESULTS: In peas and faba beans, both the E and EP processes increased the size of the NWF (P < 0.05) and decreased the size of the SWF compared with the R process. The maximum fractional rate of gas production in the first phase of fermentation was higher in the E and EP samples than in the R samples (P < 0.05). In lupins and faba beans the E and EP processes shifted the pattern of fermentation towards a more glucogenic fermentation, as represented by a lower non‐glucogenic to glucogenic ratio (NGR). Ammonia production (NH₃‐N) in the E and EP samples was significantly (P < 0.05) lower than that in the R samples. CONCLUSION: It is concluded that the E and EP processes provide a certain level of protection against ruminal breakdown to dietary protein and shift the pattern of fermentation towards a more glucogenic fermentation. Copyright © 2008 Society of Chemical Industry     

HDPE装置大型挤压机螺杆花键轴的修复

某大犁挤压机螺杆花键轴发生疲劳断裂,造成HDPE装置C线停产.该挤压机为引进设备,无备用螺杆,决定对断裂螺杆进行修复.修复后的螺杆通过检测与核算,其机械性能指标合格.实际应用结果表明其能够承受的正常的生产负荷,保证了该大型挤压机的正常运转.     

黄磷粉矿的利用与成球技术

由于黄磷生产用矿的品位逐年下降,原来不用的黄磷粉矿和中低品位浮选精矿通过成球技术已用于黄磷生产。介绍我国黄磷企业利用黄磷粉矿和浮选精矿成球的工艺技术,评述各种成球工艺的投资、成本和球团效果。     

不同制粒工艺对饲料脂溶性维生素稳定性的影响规律研究

重点监测了不同调质温度下环模制粒和挤压膨化制粒过程中,不同加工环节饲料维生素A、D3、E活性的变化,评估调质温度和制粒工艺对饲料中脂溶性维生素稳定性的影响.试验采集混合后、调质后、制粒后和打包处的饲料样品,检测样品中的水分和维生素A、D3、E的含量.结果表明,调质温度和制粒工艺对饲料中脂溶性维生素活性有较大影响,饲料中维生素A、D3、E活性损失主要集中在调质和制粒阶段,随调质温度升高而增加,且挤压膨化制粒较环模制粒对饲料中维生素A、D3、E的破坏作用更大.     

Effect of various processing techniques and different levels of antioxidant on stability of rice bran during storage

Rice bran is a major cereal by‐product available for animal feeding in many parts of the world. It has a good balance of protein, fat, carbohydrates, fiber, vitamins and minerals. The greatest restriction to the use of rice bran is its instability during storage, leading to rancidity and the presence of heat‐labile antinutritional factors. Rice bran was treated to stabilize it by extrusion cooking, roasting, pelleting and adding antioxidant (125, 250 and 375 ppm). The rice bran so treated was stored for 345 days and analyzed every 15 days for free fatty acid, peroxide and iodine values. Heat treatments were effective in stabilizing rice bran by reducing the rancidity and increasing the storage life. Roasting was effective in stabilizing rice bran for only 180 days of storage. Raw and pelleted rice bran behaved similarly with regard to stability during storage for 345 days. Addition of antioxidant in rice bran was not effective for stabilizing FFA, peroxide and iodine values. There was no difference in dose rates of antioxidant of 125, 250 and 375 ppm. Extrusion cooking proved to be the most effective process for stabilizing rice bran for prolonged storage, and roasting would be the next choice. Addition of antioxidant in rice bran was not effective for stabilizing rice bran during storage. Copyright © 2004 Society of Chemical Industry     

Effectiveness of different processing methods in reducing hydrogen cyanide content of flaxseed

A study was conducted to determine the effectiveness of reducing the hydrogen cyanide (HCN) content of flaxseed (FS) by processing. FS was processed by oven heating, single or repeated pelleting alone or in a mix with corn or other ingredients, autoclaving, and microwave roasting. The comparative effectiveness in reducing HCN in FS by these processes was monitored through HCN measurements by alkaline titration. The HCN content was 377 mg kg^?1 in raw feed‐grade FS and 139 mg kg^?1 in a human food‐grade FS. All processing methods tested significantly (p < 0.05) reduced the HCN content of FS. Autoclaving FS reduced its HCN content by 29.7%. Microwave roasting of FS reduced the HCN content by 83.3%. Because of the 5.7% water loss recorded after 4 min of FS roasting, this reduction could be related to more evaporation of the newly formed HCN. Pelleting FS once reduced HCN content by 13.3%, and three and six repeated pelleting processes reduced HCN content by 29.0% and 54.9% respectively. When FS was pelleted in a mix with 50% corn, the HCN reduction was even greater. After pelleting six times, HCN reduction reached 63.8%. However, the greatest reduction in HCN content was 73.8%, and was obtained when FS was mixed with several ingredients and pelleted twice. The HCN reduction could be the result of deactivation of the glycosidase, or the evaporation of HCN formed from cyanogenic glycosides. The HCN reduction increased as the number of pelletings and the temperature of the pelleted product increased. The greater and prolonged exposure to a higher temperature by several pelletings seems to promote a greater HCN reduction. The appropriate processing of FS is essential for the use of this oilseed in animal feeding. Copyright © 2003 Society of Chemical Industry     

粒料法合成不同相对分子质量和软段的聚氨酯分散体研究

以异佛尔酮二异氰酸酯(IPDI)为硬段、二羟甲基丙酸(DMPA)为亲水单体,采用粒料法合成了不同Mη(黏均相对分子质量)和不同软段的PU(聚氨酯)离聚物粒料,并制备了固含量约为40%的PUD(PU分散体)。结果表明:PU的Mη随R值[R=n(-NCO)/n(-OH)]增加呈先升后降态势;PU的Mη越高,PUD的平均粒径越小,粒径分布越窄,黏度越大;PUD粒子呈大小不一的球形结构,并且PU的Mη越高,PUD胶膜的拉伸强度越大;聚酯型PUD胶膜的拉伸强度大于聚醚型PUD,并且前者的软段和硬段之间相容性较好,而后者的软段和硬段之间因出现相分离现象而相容性较差;PUD胶膜的吸水率均不超过5.93%,说明其耐水性能优异。     

挤压加工和环膜制粒工艺对饲料氨基酸稳定性的影响

本文采用挤压加工和环模制粒工艺生产添加有晶体氨基酸(CAA)或微胶囊氨基酸(MAA)的水产颗粒饲料,研究2种加工过程对饲料CAA和MAA的损失,及其在水中的稳定性效果,旨在阐明挤压加工和环膜制粒工艺对饲料CAA和MAA稳定性的影响。结果表明,饲料加工对CAA和MAA的损失没有显著性差异(P>0.05),相比MAA,在饲料加工过程中晶体赖氨酸(C-Lys)和蛋氨酸(C-Met)分别多损失0.37%-8.02%和1.16%-4.29%;加工饲料的CAA在水中的损失较大,饲料水中浸滤60 min时,不同挤压温度饲料C-Lys比M-Lys多溶失23.99%-40.68%,C-Met比M-Met多溶失9.0%-13.5%;饲料水中浸滤120 min时,不同挤压温度饲料C-Lys比M-Lys多溶失24.42%-43.22%,C-Met比M-Met多溶失10.45%-17.47%。挤压温度的升高增加了氨基酸的热损失,但改善了饲料氨基酸在水中的溶失;MAA改善了CAA在饲料加工过程损失和水中的溶失。     

Effects of process conditions during expander processing and pelleting on starch modification and pellet quality of tapioca

In this study the effect of processing conditions during the manufacture of pelleted animal feed is related to the degree of gelatinization of tapioca starch as measured by the amyloglucosidase method (SGD_AGS) and Differential Scanning Calorimetry (DSC). The process conditions used were related to some physical quality characteristics of the pelleted feeds as well. Physical pellet quality was evaluated for hardness and durability, which incorporated tests that are also used in the feed industry. The processing line used in the experiment consisted of a conventional barrel type conditioner where steam pressure (100–180 kPa) and tap water addition were varied (0–52 g kg⁻¹ of the feed debit). Subsequently, expander processing was carried out and the screw speed of the expander was varied (60–140 rpm) as well as the amount of dissipated (expander) motor power (1.3–5.7 kW). Response surface regression methodology was used to assess the directions and relative magnitude of changes in processing conditions on starch modification, physical pellet quality and some system variables. The results show that no combination of independent factor levels can be found that satisfies one common maximum or one common minimum value for all of the dependent variables tested. Hardness and durability values of the pellets were most affected by steam pressure and the amount of expander motor power used, whereas starch modification was most affected by steam pressure and water addition. © 1999 Society of Chemical Industry