Enzymatic Browning in Apple Pulps

Enzymatic browning in Golden Delicious apple pulp was studied as related to degree of ripeness and temperature (3.5–31°C). Green apple pulp showed the highest rate of browning. This was attributable to differences in ascorbic acid (AA) content and polyphenoloxidase activity in young fruits. The rate of browning determined by CIE L* measurements followed complex temperature dependent kinetics, represented by a multiple linear effects with log time. Equal changes in L* parameter yielded straight lines in a log temperature vs log time plot. Inhibition with AA caused an initial slow rate of browning and a well defined break point associated with exhaustion of antioxidant properties of the AA. The greater the AA concentration the longer the initial period.     

The effect of cooking on proteins from acha (Digitaria exilis) and durum wheat

The effect of cooking on proteins from acha and durum wheat was assessed from an analysis of protein extractability, gel electrophoretic profiles, in-vitro protein digestibility (IVPD) and the amino acid compositions of wholemeal flour and residue proteins. Heating wholemeal flour samples at 100–140°C (t = 10–40 min) resulted in 0–30% and 45–55% decreases in acha and durum protein solubility, respectively. In general, high molecular weight (30–70 k Da) protein subunits were more susceptible to heat damage. For both cereals, sodium dodecyl sulphate (SDS; 10 g litre^?1) and/or dithiothrcitol (DTT; 10 mM ) increased protein solubility in unheated and heated samples. The IVPD index was 90–91% and was not significantly altered by cooking (100–120°C, t = 40 min). Cooking at extreme temperatures (140°C, t = 40 min) reduced the IVPD by 8% (P = 0.05). Osborne fractionation resulted in a durum or acha residue level of 7.8% or 55.2%. Treatment with solvent containing propanol, SDS and/or DTT at room temperature followed by SDS-polyacrylamide gel electrophoresis of non-solubilised proteins showed that the glutelin fraction of acha, with the exception of a 65 kDa subunit, was insoluble owing to strong inter-subunit hydrophobic and disulphide interactions. Wholemeal acha flour and residue protein showed a significantly greater level of hydrophobic and sulphur amino acids as well as glutamine which is associated with H-bonding. The possibility that cereal protein solubility is also dependent on protein-carbohydrate links is discussed.     

皮革去污上光用乳化蜡的研制

采用石蜡、微晶蜡为主要原料 ,经实验选出了以水为稀释剂的乳化型皮革去污上光蜡。实验优化的配方为石蜡 12 .5 g ,微晶蜡 8.0 g ,硬脂酸 8.5g ,三乙醇胺 5 .5 g ,水量 70 (涂用 )或 130 g(喷用 )。反应条件为乳化时间 4 0min ,搅拌速度 5 0 0～ 70 0r/min ,乳化温度 90℃。制得上光剂产品的去污性能可与用去污剂单独处理的效果相当 ,亮度可达 6 6 .7。     

Determination and Health Implication of the Erucic Acid Content of Broccoli Florets, Sprouts, and Seeds

The erucic acid content of broccoli florets, sprouts, and seeds was found to be about 0.8, 320, and 12100 mg/100 g, respectively. Using the erucic acid limit established for canola oil in the U.S.A. and Canada as a guideline, the estimated dietary intake of erucic acid from florets and sprouts was considered of little consequence, whereas in seeds a relatively small amount (about 35 g/wk) equaled our calculated exposure limit for erucic acid. Additionally, the most complete fatty acid distribution yet published for the various forms of broccoli are presented.     

叔丁醇氧化产物的气相色谱分析

介绍了用气相色谱分析叔丁醇两步氧化制甲基丙烯酸液相产物的组成，该分析方法能够分析液相产物中的醛类，酮类和酸类化合物共计9个组分，C2－C4有机酸无记忆效应，其色谱峰不拖尾，该分析方法的相对标准偏差≤8．5％，回收率在94．5％－103．7％之间，是一种快速，准确，操作简单的分析方法。     

提高压力过滤器滤套使用寿命的途径

佳木斯造纸厂从芬兰奥斯龙公司引进了一套新型、高效、低碱流失的压力过滤、洗涤苛化系统。本文就如何延长该系统主体元件──滤套的使用寿命这一技术问题，进行系统的阐述。     

硼酸使掺铁铝酸锂发光增强的现象

在硼酸存在下合成了掺铁铝酸锂荧光体,研究了在不同温度下硼酸加入量对荧光体发光强度的影响,并通过X射线粉末衍射和粒度分析,初步探讨了发光增加的原因。     

导汽箱产生长裂纹和大面积凹陷原因分析、处理及预防对策

对硫酸废热锅炉锅筒内自然循环的导汽箱产生长裂纹和大面积凹陷的原因作了分析，提出处理该缺陷的方法，确保了锅炉的安全运行，并提高了蒸汽的品质。     

硫酸生产中内喷文氏管的设计

从分析内喷文氏管喷头旋流特征入手 ,建立有关数学模型或表达式 ,提出对内喷文氏管喷头、收缩管支管内径、喷嘴与喉管距离进行设计的方法 ,并对设计中值得注意的问题进行理论和实践上的讨论。     

Investigation of Scale Formation in Heat Exchangers of Phosphoric Acid Evaporator Plants

The primary problem in concentrating phosphoric acid is due to fouling on the tube‐side of the heat exchangers of the evaporator units. Scaling on the heat transfer surfaces occurs because of high supersaturation of phosphoric acid liquor with respect to calcium sulphate. A review of the existing literature reveals that no information is available on heat transfer and on crystallization fouling of industrial phosphoric acid solutions. In this investigation, the solubility of different calcium sulphate types in phosphoric acid solution was studied and its dependency on acid concentration and temperature was investigated. A large number of fouling experiments were carried out in a side‐stream of a phosphoric acid plant at different flow velocities, surface temperatures and concentrations to determine the mechanisms, which control the deposition process. After identifying the effects of operational parameters on the deposition process, a model was developed for prediction of fouling resistances. The reaction of calcium sulphate crystallization followed a second order rate with respect to the supersaturation. The activation energy evaluated for the surface reaction of the deposit formation was found to be 57 kJ/mol. The predicted fouling resistances were compared with the experimental data. Quantitative and qualitative agreement between measured and predicted fouling rates is good.