الفهرس 
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Abstract
ABSTRACT
Aly Mohamed Aly Ahmed Hozayen, Factors affecting dextran formation during post harvest and processing of sugar beet roots. Unpublished Ph.D. Thesis,mesentriodes population were recorded by clear juice samples taken in March.
The lowest levels of dextran, total viable count, Leuconostoc mesentriodes population and alpha amino nitrogen content of both healthy and injured beet roots were achieved in samples treated with 2500ppm sodium benzoate or 2500ppm sodium metabisulfite solutions.
The highest values of sucrose content of both healthy and injured beet roots were obtained by use of 2500ppm sodium benzoate or 2500ppm sodium metabisulfite solutions.
Healthy and injured beet roots treated with 4% propionic acid recorded the lowest values of sodium content at the end of storage period. While the lowest values of potassium content was recorded by the use of l000ppm sorbic acid.
Dextranase led to dextran reduction in raw juic. Sixty and 65% reduction of dextran were acheaved by the addition of 20 and 30U/lOOml of row juice; respectively for 30 mm incubation. Under the same conditions, viscosity of raw juice was reduced by 50.27% and 52.5 1%; respectively.
In general, the healthy beet roots is more suitable for processing than injured beet roots. This is because of the lower levels of dextran, total viable count and Leuconosioc mesentriodes population of healthy beet roots. So it is recommended to process sugar beet roots immediately after harvest to reduce dextran increasing. If manufacturing is delayed after harvest, the roots should be treated with 2500pprn C or 2SOOppmn Na application of dextranase enzyme to remove dextran from raw juice was more efficient and economical than adding it to clear juice and syrup.
Key Words: Sugar beet, Roots, Dextran, Total viable count,
Chemical treatments, Dextranase enzyme.
Leuconostoc meseniriodes, Storage conditions,
Department of Food Science, Faculty of Agriculture, Am Shams University, 2006.
Sugar beet is becoming a growing source of sugar production. It provides about 40% of the world sugar production. The presence of dextran in sugar processing indicates of loss of sucrose, and creates problems to sugar producers by increasing viscosity lowering sugar yield, increasing molasses purities, and inhibiting filtration. This investigation was carried out to study the factors affecting dextran formation during post harvest and processing of sugar beet roots. Sugar beet roots were divided into five groups of healthy roots and five groups of injured roots (50 roots for
each group), stored for 6 days in open air after treatment with C C C and Na at different concentrations. The changes in dextran levels during different processing stages as well as the effect of harvest date, beet ccases and processing stage on total viable count and population of Leuconostoc mesentriodes were studied. The effect of different chemical treatments on the total viable count, population of Leuconostoc nesentriodes and dextran levels during storage before and after treatments were also studied. The dextranase enzyme was added to raw juice, clear juice and thick juice at different concentrations (10, 20 and 30U/1 OOml juice) for 10, 20 and 30mm at 50C.
The lowest levels of dextran during processing stages
recorded by healthy beet roots harvested during March. The
lowest values of total viable count and Leuconostoc.