预水解对硫酸盐蓝桉浆主要性质能的影响

进行了预水解硫酸盐蓝桉浆性能的研究。首先对蓝桉木片进行了5个级别的水预水解,然后对水预水解木片进行硫酸盐法蒸煮以得到3种不同卡伯值的硫酸盐蓝桉浆。实验从浆料组分、蒸煮条件、成浆卡伯值及得率、黏度、浆料纤维形态、浆料纤维表面性能及成纸主要强度性能等角度探讨了预水解对后续的硫酸盐法制浆的影响。结果表明,经过预水解的硫酸盐浆半纤维素含量从未预水解的21%～22%降到3%～4%,而纤维素含量从73%～75%增加到85%～90%。经过预水解的所有纸浆纤维长度均降低且纤维扭结指数大幅度增大。采用反相气相色谱分析法测出未预水解浆样和预水解120 min后制浆（成浆卡伯值为15）的浆样的表面能色散分量分别为30.8和34.9 mJ/m2。实验提出了2个模型方程来预估预水解中木片的质量损失和成浆卡伯值。     

不同树龄相思树混合木片硫酸盐法制浆

研究了在同一硫酸盐法蒸煮工艺条件下,大叶、马占和厚荚三种典型相思树不同树龄的木片混合蒸煮对浆料得率、硬度、强度性能和漂白性能的影响;比较了相思树混合木片硫酸盐ＡＱ法,硫化钠预处理硫酸盐法,硫化钠预处理硫酸盐ＡＱ法与常规硫酸盐法蒸煮的制浆性能     

绿液预处理对硫酸盐法制浆的影响

用热水和硫酸盐蒸煮过程中的绿液对山毛榉木片进行预处理,然后对预处理木片进行硫酸盐法制浆。在160℃下调整预处理时间,使预处理过程的木材质量损失保持在10%。随绿液用量的增加,预处理后提取物中单糖总量降低,但木素和不溶固形物含量增加。与未预处理的对照样相比,绿液(用量为2%、3%和4%)预处理硫酸盐浆的得率与之相近,而制浆过程有效碱用量降低了1.0~3.5个百分点。在预处理或制浆过程中添加AQ会提高制浆得率,且预处理过程添加AQ的效果更明显。绿液预处理硫酸盐浆的黏度比对照样高;当绿液用量为2%、3%和4%时,预处理硫酸盐浆手抄片的抗张强度、耐破度和撕裂度与对照样成纸强度相近或偏高。就预处理和制浆效果而言,最佳绿液用量为2%或3%。     

桉木硫酸盐法蒸煮前预提取聚木糖的研究

研究了桉木硫酸盐法制浆前的半纤维素提取工艺。对桉木片进行预水解处理,通过改变温度和时间对半纤维素提取工艺进行优化。水解液中提取的聚木糖为12~38 g/L,相当于木片质量的9%-15%。对预水解后木片进行硫酸盐法蒸煮,结果表明,与未经预水解相比,预水解后木片更容易脱木素,成浆更易漂白,预水解中聚戊糖去除得越多,所得浆料的强度性能越低。     

预水解对硫酸盐蓝桉浆主要性质的影响性能的影响

进行了预水解硫酸盐蓝桉浆性能的研究。首先对蓝桉木片进行了5个级别的水预水解,然后对水预水解木片进行硫酸盐法蒸煮以得到3种不同卡伯值的硫酸盐蓝桉浆。实验从浆料组分、蒸煮条件、成浆卡伯值及得率、黏度、浆料纤维形态、浆料纤维表面性能及成纸主要强度性能等角度探讨了预水解对后续的硫酸盐法制浆的影响。结果表明,经过预水解的硫酸盐浆半纤维素含量从未预水解的21%~22%降到3%~4%,而纤维素含量从73%~75%增加到85%~90%。经过预水解的所有纸浆纤维长度均降低且纤维扭结指数大幅度增大。采用反相气相色谱分析法测出未预水解浆样和预水解120 min后制浆(成浆卡伯值为15)的浆样的表面能色散分量分别为30.8和34.9 mJ/m2。实验提出了2个模型方程来预估预水解中木片的质量损失和成浆卡伯值。     

水预水解提取半纤维素对桉木碱法制浆的影响

研究了150℃和160℃下4种反应时间桉木片热水预处理对半纤维素预提取及后续烧碱-蒽醌法和硫酸盐法制浆的影响.结果表明,热水预处理对半纤维素水解糖提取效果显著,戊聚糖提取率在27%～43%.与未预处理木片相比,预处理后木片综纤维素含量降低约12%,木素含量下降了11%,苯-醇抽出物和1%NaOH抽出物含量均大幅度上升.木片经热水预处理后,碱法制浆性能提高,易成浆,可降低用碱量,缩短蒸煮保温时间,而且与原木片碱法制浆相比,相近蒸煮条件下浆料卡伯值下降7～10个百分点,浆料己烯糖醛酸含量下降75%～95%,原浆白度升高4～6个百分点,黏度有小幅度降低,得率下降1.5～4.5个百分点.     

桉木冷碱浸渍-挤压-硫酸盐法制浆的研究

将冷碱浸渍-挤压作为木片预处理方法,并应用于桉木硫酸盐法制浆的前段。探讨了冷碱浸渍-挤压的最佳工艺条件,研究了蒸煮工艺条件对预处理后料片蒸煮结果的影响,对比了未预处理原料与预处理后料片硫酸盐法蒸煮所得纸浆的强度性能。结果表明,木片经过冷碱浸渍-挤压后,易于蒸煮,从而可减少蒸煮用碱量或降低最高蒸煮温度、缩短保温时间,且蒸煮的均匀性得到改善,筛渣率降低、纸浆强度性能提高。最佳预处理工艺条件为浸渍用碱量2%,浸渍时间2 h,温度25℃,液比1∶5,挤压压缩比3∶1;与未预处理原料硫酸盐法蒸煮(用碱量21%)相比,预处理后料片在总用碱量(浸渍用碱量2%,蒸煮用碱量19%)相同的情况下,成浆卡伯值降低了1.7,细浆得率只降低0.14个百分点,且纸浆强度性能更优,其中,抗张指数、耐破指数、耐折度分别提高了7.0%、5.2%、66%,撕裂指数与未预处理原料硫酸盐法蒸煮所得纸浆相近。     

人工种植桉木深度脱素的研究：第一部分：深度脱木素的原理

进行了４种桉木改良硫酸盐法制制浆的实验,结果表明改良硫酸盐法制浆的选择性明显高于常规蒸煮法,改良硫酸盐法在浆料强度不受损失的前提下,纸浆的卡伯值较常规硫酸盐法低５－６个单位。     

桉木RDH硫酸盐法制浆性能的研究

研究了桉木RDH（快速置换加热）硫酸盐浆的制浆性能，对桉木RDH硫酸盐法制浆时，用碱量、H－因子、白液的硫化度以及在温黑液预处理段温黑液的活性碱浓度和硫化度等蒸煮条件，对最终制浆结果的影响进行了研究。结果表明：与常规硫酸盐法制浆相比，RDH硫酸盐法制浆时的用碱量相对较高（常规KP法和RDH法的用碱量分别为14％和15％，Na2O计），但RDH纸浆的硬度较低（分别为17．0和11．7）；在纸浆达到相似或较低硬度的情况下，RDH法制浆可以缩短蒸煮时间，或在相同的H－因子下，降低纸浆的卡伯值；在一定的范围内提高白液蒸煮段白液的硫化度，可以降低RDH纸浆的卡伯值或提高纸浆的得率，在温黑液预处理段，温黑液的活性碱浓度和硫化度会对RDH纸浆的最终结果产生较大的影响，对纸浆物理性能的分析结果表明，RDH纸浆在低卡伯值条件下也具有较高的强度性能，但与常规硫酸盐浆相比，RDH纸浆的撕裂强度相对较高耐抗张强度相对较低。     

半纤维素预抽提对硫酸盐桦木浆性质的影响

将半纤维素预抽提与化学制浆工艺相结合,可将溶出的糖类物质转化成燃料及化学品。首先用热水或硫酸盐蒸煮的白液（NaOH、Na2S和Na2CO3）对白桦（Betula pendula）木片的半纤维素进行抽提,抽提工艺条件为：时间20～90min,温度130～160℃,有效碱用量为0～7%。对抽提后的木片进行硫酸盐法蒸煮、打浆及抄片,并与未抽提的试样进行对比。结果表明,硫酸盐法蒸煮前用蒸煮白液对木片进行抽提可将木聚糖溶出,但不会降低浆料得率和成纸强度,同时可将蒸煮用的碱液预浸到木片中,但当抽提液pH值〉10时会降低木聚糖浓度。热水抽提工艺溶出的木聚糖浓度最高,所得的水解液中不存在有毒或抑制性的无机物和极少的可溶木素,可用木聚糖酶水解成木糖单体和发酵成丁二酸。然而,热水抽提会对浆料性能产生不利影响,如降低成纸的压缩强度、耐破度、抗张强度及挺度,但伸长率变化较小,撕裂度稍有改善。     

一种食品成形机设计方案反求

成形机是淡水鱼方便食品加工的关键设备之一 ,目前国内还没有十分成功的设计先例 ,本文应用反求设计的思想 ,对淡水鱼方便食品成形机的设计进行讨论 ,得出了恰当的设计方案 ,实践证明所得的结论有效、可行。     

β-O-4型木素模型化合物的合成及其在GIF型仿酶降解体系中的变化(

研究了一种β-O4型木素模型化合物--4-(α-(2-甲氧基苯氧基)-乙酰基)-愈创木酚的合成方法,并利用薄层色谱(TLC)、红外光谱和核磁共振谱(1H-NMR)等手段对它们的化学结构进行了分析与确认.采用由Cu2+/吡啶/过氧化氢组成的GIF型仿酶系统对这一木素模型物进行仿酶降解,结合高效液相色谱(HPLC)及GC-MS等分析方法,分析了该β-O4型木素模型化合物在降解过程中的结构变化,并对这种仿酶降解的机理进行了探讨.研究结果表明通过利用过量愈创木酚和4-乙酰基愈创木酚的溴化物的反应并结合羟甲基化可以得到含α-羰基的酚型β-O4木素模型化合物.GIF仿酶降解体系对β-O4型木素模型物有较强的碎解能力,降解后产生较多的脂肪族小分子化合物,一部分成为香草醛、香草酸等低分子芳香族化合物,该结果可以说明此降解体系能有效导致β-O-4型木素模型化合物的各种类型的裂解反应.     

Determination of vitamin a in foods ‐ a review

Formerly, few foods were routinely analyzed for vitamin A, but recent emphasis on nutrient requirements, nutrient labeling, and use of dietary convenience foods has created need for determining vitamin A in a variety of foods. There are many vitamin A methods — some suitable for certain products only. For regulatory purposes, the FDA specifies the AOAC method where it is applicable. However, some food analysts and organizations continue with their own vitamin A methods. If possible, a single, widely applicable general method should be used for vitamin A in foods. Vitamin A may be determined by spectrophotometric, colorimetric, and fluorometric procedures. Sometimes chromatography is required as an important part of the method. Colorimetric procedures with SbCl₃ are now most widely used to measure vitamin A (retinol) in foods. If vitamin A content is high enough and extracts sufficiently free of interfering substances, spectrophotometric or flurometric methods are satisfactory. Methods in various stages of development for determining vitamin A in foods are based on flurospectrophotometry, gas‐liquid chromatography, high‐performance liquid chromatography, and automation. To estimate total vitamin A nutritional value of certain foods may also require determination of vitamin A isomerization and contents of carotenes, cryptoxanthin, reinaldehyde, and apo‐carotenal.     

啤酒发酵罐的清洗和灭菌技术

发酵罐的微生物状况对啤酒质量影响很大,清洁无菌是啤酒生产中卫生管理的基本要求。良好的CIP系统可以对发酵罐进行有效的清洗。本文对发酵罐的清洗机理、清洗方法、清洗程序、清洗剂和灭菌剂的选择以及CIP系统的运行质量等问题进行了探讨。     

Colour evaluation of freeze-dried roselle extract as a natural food colorant in a model system of a drink

The roselle extract, using acidified water-95% ethanol (1:1) as a solvent, was subjected to freeze-drying. Maltodextrin and trehalose, 2 and 3 g/100 ml extract, were used as stabilisers. Addition of the stabiliser retarded anthocyanin degradation. Colour changes of the freeze-dried roselle powder during storage were monitored using the CIELAB system. It was found that pigment concentration markedly changed with a minor change in lightness and hue. However, the changes in chroma mainly came from anthocyanin degradation. The freeze-dried roselle powder with maltodextrin (3 g/100 ml) proved to have superior colour stability. A model system of a drink adding this powder was carried out and the colour evaluation was compared to drinks containing commercial colorants: SAN RED RC^® and carmoesin. During a 12-week storage period at 30 °C, the change in hue of all three groups was within the same shade suggesting any change in pigment concentration had insignificant effect on hue shift. By contrast, the degradation of pigments highly correlated to changes in lightness and chroma. Even though a drink with roselle anthocyanin powder was the least stable in colour, the overall appearance of the drink was rated close to ‘like slightly’ throughout 56 days.     

Optimization of a Wall Material Formulation to Microencapsulate a Grape Seed Extract Using a Mixture Design of Experiments

The microencapsulation by spray drying of a commercial grape seed extract (GSE) using maltodextrin (MD), mesquite gum (MG), and zein (Z) as wall materials was investigated. A mixture design of experiments (MDOE) with the three wall material components was used to find optimal wall material formulations. The parameters used to evaluate the microcapsules obtained were encapsulation efficiency (EE), encapsulation productivity (EP), release of the core material in water (RE Water), hygroscopicity (MH), and degree of caking (CD). Four optimal formulations were then selected and evaluated including antioxidant activity (AA), release of the core material at pH 1, 4, 7, and 10, and in simulated gastric (GF) and intestinal fluid (IF), morphology and glass transition temperature (Tg). Microcapsules had a smooth surface with sizes ranging from 4 to 16 μm, a Tg of 160?±?1 °C, and an AA of 1.90?±?0.05 mmoles Trolox/g. The two formulations with the most optimal results were T3 (44 % MG-56 % Z) and T4 (34 % MD-66 % Z), with an EE of 85 % and 82 % and an EP of 98 % and 99 %, respectively. The release was between 50 % to 52 % for T3 and 52 % to 55 % for T4 at the different pHs. The RE in GF and IF were 70 % and 63 %, respectively, for T3, and 71 % and 63 % for T4; most of the release happened during the first hour. Both formulations protected the GSE from thermal degradation at temperatures up to 180 °C.     

基于VB的PC机与单片机串行通信的米厂控制系统设计

主要介绍在大米加工厂，如何实现对各设备的监控。在分析大米加工工艺流程和硬件接口连接的基础上，探讨了如何利用VB语言和单片机汇编来编程实现串行通信以及系统是如何抗干扰的。     

圆网纸机改造为长网纸机的技术创新

介绍了国内某企业4600 mm圆网纸机改造为长网纸机的情况。纸机车速由改造前的120～150 m/min提高到350～500 m/min;纸机产品由原来的挂面箱纸板改为52～150 g/m2铜版原纸,产品档次提高,生产的铜版原纸质量达到用户要求;单台日产量由改造前的50～70 t提高到200～250 t;改造后电耗、煤耗、浆耗、水耗均有下降;改造后企业的经济效益明显提高。