Process Parameter Effects on Particle Residence Time in a Vertical Scraped Surface Heat Exchanger

Residence times of 1.0-2.0 cm potato cubes with 0.4-1.2% aqueous solutions of sodium carboxymethyl cellulose flowing at 453-599 mli sec were investigated in a vertical scraped surface heat exchanger rotating at 60 160 rpm. Minimum and maximum normalized particle residence times (NPRTs) standard deviation of mean NPRTs, and characteristic parameter for tanks-in-series models were not significantly affected by particle concentration. Mean NPRT for 40% particle concentration was significantly higher than those of single particle - 20% particle concentrations. Mean NPRTs were significantly influenced by process parameters and 2-way interactions.     

NONENZYMATIC BROWNING IN DRIED RED PEPPER PRODUCTS

The nonenzymatic browning of dried red peppers was studied under various water activities, storage temperatures, and packaging atmospheres. Whole pepper and pepper powders-coarse and fine, with and without seeds-were compared. The browning can be described by the zero order reaction, and the rate constant is strongly affected by water activity and temperature. Flushing the package with nitrogen did not have a significant effect on the browning rate. For minimum browning, the peppers should be stored at water activities below 0.3 and in the form of whole pods or coarse powder with seeds.     

CHANGES IN 'DELICIOUS' APPLE BROWNING AND SOFTENING DURING CONTROLLED ATMOSPHERE STORAGE

High CO₂ conditions offered no advantage over normal CA storage in terms of reduced ‘Delicious’ apple browning or softening during a 28 week storage period. After approximately 7–14 weeks in CA storage, ‘Delicious’ apples showed significant losses in PPO activity, browning tendency and firmness. Electrolyte leakage reached a maximum at 11.5 weeks and declined, while total phenolics remained fairly constant. The changes observed may indicate a loss in membrane integrity and decompartmentalization after 7–14 weeks of storage, which may in turn allow for increased enzymatic browning. Polygalacturonase activity was only detectable at harvest. Holding apples for additional time in air following removal from CA storage appears to accelerate changes in these characteristics.     

CLONING, EXPRESSION AND CHARACTERIZATION OF NOVEL LECTIN FROM ORYZA SATIVA

A lectin gene homolog of Oryza sativa was successfully cloned and expressed in Escherichia coli. The deduced amino acid sequence of the protein product showed a significant similarity with known chitin‐binding lectins. Most of the recombinant lectin was found in an insoluble aggregated form as inclusion bodies and only a small part was in the culture medium in a soluble active form. Functional recombinant lectin was recovered from the inclusion bodies by solubilization with 8 M urea in Tris/HCl buffer, pH 7.0 and renaturation by 10‐fold dilution in the same buffer. The recombinant lectin with His‐tag was simply purified to homogeneity by the process of affinity chromatography and was obtained with a yield of 6–8 mg/L culture. The recombinant lectin was a homo‐dimer composed of 22 kDa. The hemagglutination activity of the recombinant lectin was optimal at pH 4.0–7.0 and it was very sensitive to inhibition by N‐acetylneuraminic acid and thyroglobulin.     

Accelerated Maturation of Cheddar Cheese: Influence of Added Lactobacilli and Commercial Protease on Composition and Texture

The addition of live and heat-shocked Lactobacillus casei-casei L2A and Neutrase© was tested for its ability to accelerate the maturation of Cheddar cheese. An evaluation of physicochemical and rheological properties showed that cheese pH was decreased by bacterial and enzymatic additives, while fracturability and cohesiveness were influenced principally by Neutrase. The integrated process recommended is composed of three parts: first, the addition of live L. casei-casei L2A to control the undesirable microflora, second, heat-shocked cells of the same species at a concentration of 1.0%, and third, Neutrase at a concentration not higher than 1.0 × 10^-5 AU/g of cheese. This process led to a good-quality sharp Cheddar cheese with 60% increase in flavor intensity compared to control cheese.     

Control of H2O generated during the CO2 hardening process in a casting mold

An additive reagent was introduced into a water glass binder system for enhancing the mechanical properties and dimension stability of a casting mold, and for improving the surface quality of a cast product. Two different processes with three different additive reagents were employed to investigate the relation between fracture strength of the mold and water (H₂O) existed in the mold. In processes I and II, the mold samples were coated with a water glass binder, and then dipped into different solutions with additive reagent after and before carbon dioxide (CO₂) hardening, respectively. The fracture strength of the mold was enhanced by reducing H₂O content in the mold, achieved by a hydrolysis reaction of additive reagents. In process I, the H₂O movement was restricted in the mold by the solid phase, converted from the water glass during CO₂ hardening. When employing process II, especially in the TEOS used as additive reagent, the fracture strength was significantly increased due to the effective reduction of H₂O content in the mold and the homogeneous generation of glass phase by a sol–gel reaction of the additives.     

AN INVESTIGATION ON THE EFFECT OF MANGANESE SPECIFICATION IN BASIC OPEN HEARTH PROCESS

本文结合生产研究了鞍钢碱性平爐冶炼重轨和无缝等碳素镇静钢的锰制度.研究结果指出:就上述鋼种而言,熔炼过程中的锰制度对钢中氧、硫含量以及轧制的成品質量並没有实际影响,换句话说,并没有必要规定熔池含锰量高於一定水平(>0.15—0.2%Mn).相反地,熔池含锰较高或在熔炼过程中加入锰铁均使降碳速度趋於缓慢,从而延长了熔炼时间.因此,只要高炉铁水中含硫量能够合乎规定,用低锰生铁作原料对炼钢並无害处.通过高爐生产数据分析,说明在鞍钢的操作条件下完全有可能生产含锰低而含硫合乎上述规定的铁水,应该认为用低锰生鉄冶炼重轨和无缝类型的优質鋼是切实可行的.