Purification and Characterization of an Endoprotease from Melon Fruit

An endoprotease was purified from melon fruit (Cucumis melo L.) by ammonium sulfate precipitation, gel filtration and ion-exchange chromatography using t-butyloxycarbonyl-Ala-Ala-Pro-Leu p-nitroanilide as a substrate. The molecular weight was estimated as 26,000 and isoelectric point pH 9.5. It preferentially hydrolyzed peptide bonds of the carboxyl terminal sides of Leu, Ala, His, Gin, and Am. Activity was strongly inhibited by diisopropyl phosphofluoridate, indicating the serine protease nature of the enzyme. The migration distance on electrophoresis, molecular weight and substrate specificity differed from cucumisin, a known protease from melon. This unusual protease may have potential for special food treatment applications.     

EFFECT OF HOT WATER IMMERSION ON PEEL COLOR OF PEARS AND ON WHITE ROT CAUSED BY BOTRYOSPHAERIA BERENGERIANA

Abstract The effectiveness of hot water immersion (HWI) on peel color and the control of white rot caused by Botryosphaeria berengeriana on wound-inoculated European pears, cv. La-France, were investigated. After HWI at 40, 45, 48, 50, 52 and 54C for varying immersion periods, the pears were held at 20C, ≥ 90% RH (simulated retail conditions). The peel color (L*, a*, b*) was determined before and after HWI treatment. The dominant role of L* suggested that peel darkening was the major factor in color change of the HWI treated pears. The L* value of 54 was judged as the border line for acceptability and less than 51 resulted in browning. Similarly the critical points for a*, b*, chroma, hue and ΔE* were found to be −6, 34, 35, 100, and 8, respectively. Disease incidence recorded 7 days after treatment revealed that High Temperature Short Time (HTST) treatment of 54C for 3 min reduced incidence about 85% with good retention of color. Both temperature and immersion period are to be carefully selected to prolong shelf-life and retain the peel color quality of 'La-France'pears.     

Thermal Transitions of Myosins/Subfragments from Black Marlin (Makaira mazara) Ordinary and Dark Muscles

Thermal transitions were studied by means of differential scanning calorimetry (DSC) and a spectrophotometric method. Three endothermic peaks (40, 43, 50°C: ordinary muscle; 46, 54, 62°C: dark muscle) were observed in DSC thermograms of both myosins. Thermograms of S-l fragments showed one peak (41°C: ordinary muscle, 43°C: dark muscle). But ordinary and dark muscle rod fragments gave two peaks (41, 62°C) and one peak (58°C), respectively. The spectrophotometric results also showed two thermal transitions for both myosins and one transition for their S-1 fragments. However, the rod from ordinary muscle myosin had two transitions, whereas that from dark muscle myosin had one transition.     

日本分散型生活污水处理技术与设施建设状况分析

日本的生活污水处理是由下水道事业(指城市污水处理厂及管网建设)、农业村落污水处理事业以及净化槽事业构成。其中农业村落污水处理事业以及净化槽事业面向农村等人口密度较小区域,以分散型生活污水处理为基本处理模式。下水道事业长久以来是以大城市下水道的建设为中心发展而来,近年来地方城市等小规模的下水道建设得到全面推进。然而日本的湖泊及内海等封闭型水域的富营养化问题日益严重,水环境的改善趋势长期得不到认可,为此面向分散型生活污水的深度处理技术也得到了发展与推广。基于日本的公开资料,通过相关技术发展状况的分析调查,结果表明,日本采用的主要深度处理技术分为间歇曝气工艺、深度处理氧化沟工艺、膜分离活性污泥工艺,这三种工艺均由生物脱氮与絮凝沉淀除磷单元组合而成,被积极应用于农业村落污水处理事业中。     

Deamidation and Functional Properties of Food Proteins by the Treatment with Immobilized Chymotrypsin at Alkaline pH

Ovalbumin, lysozyme, 7S globulin, 11S globulin, and gluten were treated with immobilized chymotrypsin on controlled-pore glass at pH 10 at 20°C to improve their functional properties. Optimum pH of deamidation of ovalbumin by immobilized chymotrypsin was 10, where proteolysis was very limited. Deamidation percentages of ovalbumin, lysozyme, 7S globulin, 11S globulin, and gluten were 10.0, 8.4, 6.0, 5.0, and 8.0, respectively. SDS polyacrylamide gel electrophoretic patterns of ovalbumin and lysozyme showed no difference between untreated and treated proteins, while those of soy proteins and gluten showd that larger molecular weight fractions were dissociated into smaller molecular size fractions. Solubility of gluten was greatly improved at all pHs, 2-12. Both emulsifying and foaming properties of proteins were improved by treatment with immobilized chymotrypsin.     

Preparation and Characterization of Machinable Mica Glass-Ceramics by the Sol-Gel Process

The preparation and characterization of machinable mica glass-ceramics by the sol-gel process are described. The thermal behavior of the precursor and the optimum conditions for calcination, molding, and sintering are given. Physical, chemical, thermal, electrical, and mechanical properties are investigated, and the machinability of the ceramics is discussed.     

Rheological Properties of Heat-Induced Ovalbumin Gels Prepared by Two-step and One-step Heating Methods

Ovalbumin gave a transparent solution, transparent gel, or opaque gel on heating at low ionic strength, but a turbid gel, or turbid suspension at high ionic strength (one-step heating). The ovalbumin solution, once heated at low ionic strength, gave a transparent gel with a second heating at high ionic strength (two-step heating). Textural parameters of hardness and adhesiveness, viscoelastic parameters from creep curves, breaking energy and water-holding capacity of these gels were measured. Transparent gels by the one- or two-step heating were firm and elastic and had high water-holding capacity. Turbid gels by one-step heating were soft and less elastic and had low water-holding capacity. The relationship between gel properties and structure was discussed.     

MOTION OF AND MASS TRANSFER FROM AN ASSEMBLAGE OF SOLID SPHERES MOVING IN A NON-NEWTONIAN FLUID AT HIGH REYNOLDS NUMBERS

An approximate solution for the motion of an assemblage of solid spheres moving in a power-law fluid in the high Reynolds number region is obtained using a combination of Happel's free-surface cell model and the boundary layer theory. It is theoretically predicted that the drag coefficient will decrease with the increase of the shear-thinning anomaly. The results of the present analysis are in reasonably good agreement with the available experimental data for fixed and fluidized beds. The influence of the non-Newtonian behavior on the mass transfer rate from an assemblage of solid spheres is also discussed.     

SEDIMENTATION OF PARTICLES IN NON-NEWTONIAN FLUIDS

The influence of non-Newtonian flow behavior on sedimentation velocity of particles is investigated using an approximate solution for the motion of an assemblage of solid spheres presented previously by the authors. It is theoretically predicted that the pseudoplaslicity decreases the sedimentation velocity and its reduction is pronounced at large voidage. The present theory is discussed using the available empirical correlations.     

A Fast Display Method of Sky Colour Using Basis Functions

Computer graphics are being used for visual environmental assessment or architectural designs. Displaying the sky as a background is indispensable in generating photorealistic images for such applications. In this paper, we propose a fast display method of the sky colour by expressing the intensity distribution of the sky using basis functions, even if the sun position and/or the camera position are altered. In the proposed method, cosine functions are used as basis functions. The sun altitude is altered at certain intervals and the distributions of the sky colour for each sun altitude are precalculated and stored efficiently using basis functions. The colour of the sky in the view direction of an arbitrary sun position can be obtained from the stored distributions and displayed quickly. © 1997 by John Wiley & Sons, Ltd.