Measurements of natural radionuclides in soil samples from Upper Egypt

This paper presents the results of natural radioactivity measured for the soil of Qena using gamma-ray spectrometry at ZSR, Hanover University, Germany. Soil samples of radioactive concentrations of ^238U-series （^234Th, ^214pb, and ^214Bi）, 232Th-series （^228Ac, ^212pb, and ^208Tl） and ^40K were analyzed. Three objectives were set： （1） activity levels by surface soft sampling at 0-30 cm depth, （2） dose rates of gamma radiation, radium equivalent, index hazard, and effective dose, and （3） ambient dose rates.     

A Microbiological Study of Sudanese Date Wines

Procedures followed in the home fermentations of three date wines were investigated. Two wines, 'sherbote', and‘nabit’prepared from date sirup, are produced by a relatively quick fermentation taking about 36-48 hr. The fermentation of the third wine;‘dakkai', prepared from whole date fruits, is a slow process taking about 96 hr. The samll amounts of spices and sorghum malt used as additives in the preparation of 'sherbote’and‘nabit', respectively, contribute to the inoculum. In‘dakkai’fermentation of the inoculum comes from the natural flora of the data fruit itself. Changes in the production of ethanol, acetic and lactic acids and pH as well as in microbial populations were followed during fermentation of each wine. The most important genera of yeast, acetic and lactic acid bacteria were identified.     

Water Stress and Quality Decline during Storage of Tropical Leafy Vegetables

The effect of water stress (excessive water loss) on postharvest quality during storage of tropical leafy vegetables Brussica junceu L. and Amaranthus caudatus L. at ambient (24°/28°C) and low temperature (2°/4°C) regimes has been investigated. Exposed, nonsealed B. juncea and A. caudutus leaves lost water rapidly during storage at either temperature regime resulting in accelerated decrease in leaf turgidity (wilting), chlorophyll, ascorbic acid and soluble protein content, and an increase in amino acids, in the stressed leaves. Alleviation of water stress by sealing the leaves with thin plastic film restricted chlorophyll, soluble protein and ascorbic acid loss, particularly when the leaves were cooled, and maintained their turgidity. Both leafy vegetables appeared tolerant to chilling injury.     

EFFECT OF EMULSIFIERS AND FUNGAL α-AMYLASE ON RHEOLOGICAL CHARACTERISTICS OF WHEAT DOUGH AND QUALITY OF FLAT BREAD

Teftoon, a flat bread made of whole wheat flour, is prepared by hand sheeting of dough, followed by baking. Different emulsifiers, like lecithin, E471 (distilled monoglyceride) and E472 (diacetylated tartaric acid esters of mono- and digelycerid of fatty acids), were added to the flour at various levels ranging between 0.25 and 1.0% w/w, and it was observed that they improved the dough characteristics. Improvement in bread quality parameters, such as force to tear and sensory acceptability, were monitored. Fungal α -amylase was also incorporated into the flour at 5–20 g/100 kg flour basis alone and in combination with the emulsifier. The force required to tear the fresh bread was decreased with emulsifier and enzyme addition; however, E472 addition at 0.75% w/w of whole wheat flour gave the softest bread. The tear force of stored bread significantly increased with storage; however, bread containing E472 showed a less increase in tear force up to a period of 3 days. The sensory acceptability was found to be higher than that of the control bread for emulsifiers, and lower for enzyme at a concentration higher than 10 g/kg flour.

PRACTICAL APPLICATIONS

Flat bread is normally consumed fresh, but the staling phenomenon starts immediately after baking this kind of bread. Today, large-scale production and increased consumer demands for high-quality bread with long shelf life have created the need for functional food additives such as emulsifiers and α -amylase enzyme. Incorporation of emulsifiers and enzyme decreased the hardness of Taftoon bread. Emulsifiers and α -amylase enzyme enhanced the flat bread dough quality. The sensory acceptability also improved with the addition of emulsifiers. Optimizing the amount of emulsifiers and enzyme required for reduction of bread hardness is vital because the quality and price of the final product depend on this parameter.     

EFFECTS OF PLANT EXTRACTS ON ARYL HYDROCARBON HYDROXYLASE ACTIVITY AND 3H-BENZO(a)PYRENE BINDING TO DNA

Eight plant species belonging to different families were extracted and fractionated by organic solvents and their total extracts were tested against aryl hyrocarbon hydroxylase (AHH) activity and ³H-benzo(a)pyrene binding to DNA in vitro. The n-butanol extract was more effective than the extracts of chloroform and petroleum-ether, respectively. None of the aqueous extracts showed any inhibitory effects on both AHH activity and ³H-benzo(a)pyrene binding to DNA. The extracts obtained from Cypressus sempevirens L., Anchusa strigosa L., Myrtus communis L., and Crataegus monogyna L. were more effective than the extracts from Achillea santolina L. and Thuja occidentalis L. However, extracts obtained from Adiantum capillus-veneris L. and Salsola rosamarinus L. exhibited no effects. The results suggest that the inhibitory effects of these plant extracts on AHH activity and ³H-benzo(a)pyrene binding to DNA might have similar effect in vivo and there might be used in the prevention of cancer .     

Performance analysis of two serial-search acquisition schemes for FH spread spectrum signals

Initial synchronization (acquisition) schemes of frequency hopped (FH) spread spectrum signals often make use of serial-search acquisition techniques. Two FH serial-search acquisition schemes are introduced and analysed. These schemes are the fixed dwell-time with false alarm memory (FDT/FAM) and the double dwell-time with binary integration (DDT/BI) scheme. Statistical properties namely, probability density function, characteristic function and mean value of the random acquisiton time of each acquisition scheme are obtained. The performances of the FDT, FDT/FAM and DDT/BI acquisition schemes are established and compared in the presence of partial band noise jamming, partial band tone jamming and additive white gaussian noise (AWGN). The results indicate that the DDT/BI acquisition scheme outperforms the FDT and FDT/FAM acquisition schemes.     

MECHANICAL DAMAGE INDUCED BY CONTROLLED FREEZING IN APPLE AND POTATO

Freezing was used to induce controlled damage to apple and potato parenchyma. As the tissue freezes ice crystals form extra- or intracellularly, pushing the cells apart or rupturing cell walls producing large voids within the tissue. Mechanical tests (wedge penetration, tensile and compression) on specimens frozen to a certain temperature at a controlled rate and thawed show that the changes in the mechanical behaviour of the material are directly related to the degree of cell damage. As the tissue freezes, the fastest rate of tissue damage occurs between -3C and -10C. In this range there is a marked decrease in stiffness and an increase in the deformation required to cause failure. In apples, slow freezing leads to the intercellular spaces expanding, increasing their aspect ratio and hence, the anisotropy of the tissue. The increasing number of voids increases crack-stopping and ductility; more energy is dissipated in flow elevating the fracture toughness. Toughness then decreases with further damage. This effect can be mimicked with brittle paper: fracture toughness of tracing paper initially increases with increasing number of holes punched randomly in it.