MARC 主機 00000nam  2200349   4500 
001    AAI9211204 
005    20081217132320.5 
008    081217s1991    ||||||||||||||||| ||eng d 
035    (UMI)AAI9211204 
040    UMI|cUMI 
100 1  Prakash, Anuradha 
245 14 The effect of microwave energy on the structure and 
       function of food hydrocolloids 
300    165 p 
500    Source: Dissertation Abstracts International, Volume: 53-
       01, Section: B, page: 0021 
500    Adviser: Poul M. T. Hansen 
502    Thesis (Ph.D.)--The Ohio State University, 1991 
520    The aim of this project was to understand how microwaves 
       interact with functional food ingredients and to determine
       the effects they have on their structural and functional 
       properties. The gelatinization patterns of microwaved and 
       conventionally heated starch granules were observed. 
       Although no differences in the process of gelatinization 
       by the two methods of heating were found, it was found 
       that in the conventionally heated samples, the smaller 
       particles took longer to gelatinize than the larger ones. 
       A protocol was developed to determine the particle size 
       distribution of potato starch granules 
520    Time-temperature profiles were obtained for dry starch 
       powders equilibrated to a range of water activities and 
       heated in a microwave oven. The maximum temperature 
       achieved was not a linear function of equilibrium moisture
       content, but reached a maximum at a water activity level 
       of 0.65. No gelatinization of starch granules was observed
       at the low water activity levels and only slight 
       gelatinization was observed at the higher water activity 
       levels 
520    Dielectric data was obtained for potato starch, locust 
       bean gum, gum arabic, carrageenan and 
       carboxymethylcellulose. Both the dielectric constants and 
       the loss factors increased with increasing moisture 
       content and temperature. Locust bean gum and potato starch
       are neutral polysaccharides compared to the other three 
       polysaccharides that carry considerable charge. The values
       predicted by model equations were not significantly 
       different from the measured values indicating that these 
       models could be used to predict the dielectric properties 
       of hydrocolloids within the moisture, temperature and 
       charge range specified earlier. Moisture was found to be 
       the most important factor in determining the dielectric 
       properties of the hydrocolloids 
520    To determine the effect of microwave energy on the 
       functional properties of hydrocolloids, a model system 
       consisting of carrageenan-milk gels was prepared. The gels
       were subjected to conventional and microwave heat 
       treatment. There was a significant difference in the 
       microstructure of the gels heated by the two methods as 
       observed by scanning electron microscopy. Also, there was 
       a difference in the gel strength as measured using the 
       Instron Universal Testing Machine. The gels that had been 
       microwaved had greater gel strength compared to the gels 
       that had been heated conventionally. (Abstract shortened 
       with permission of author.) 
590    School code: 0168 
590    DDC 
650  4 Agriculture, Food Science and Technology 
650  4 Chemistry, Radiation 
690    0359 
690    0754 
710 2  The Ohio State University 
773 0  |tDissertation Abstracts International|g53-01B 
856 40 |uhttp://pqdd.sinica.edu.tw/twdaoapp/servlet/
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