| Summary: | 碩士 === 國立臺灣大學 === 食品科技研究所 === 89 === On october 26,1999,US Food and Drug Administration（FDA）approved the labeling of foods containing soy protein for reducing the risk of coronary heart disease. The announcement attracts more consumers’ attention on the soy related products. Most of soy products utilize soy as the sole resource. New product can be developed when soy is mixed with starch in appropriate manners. This is beneficial to broaden the applications of soybean and to promote food technology.
The experimentation is to investigate the effect of adding corn starch on the gelation mechanism and gel structure of soy protein.There are three typies of soybean protein： soy protein isolate（I）、 soy protein concentrate（C） and soybean flour（F）. Complex I-S、C-S and F-S are made by mixing three typies of soybean protein and corn starch. The determination of thermal and rheological properties would be the evidence on discussing the interaction between protein and starch. Microscopic observation (using both scanning electronic microscope and light microscope) is to understand the gel structure and distribution of starch and protein. The presence of starch granule will be doubly checked. From the analysis, it is to establish the relations between properties of raw material (e.g. thermal property, rheological property) and product characteristics (e.g. rheological property, texture attributes). The results will be used for developing new products.
The results showed that in the I-S and C-S mixed systems, starch and soy protein complex was the continuous phase as starch/protein ratio smaller than the value 0.4. Protein was the non-continuous phase (filler) as starch/protein ratio larger than the value 0.6 in I-S and C-S system, and as the ratio larger than the value 0.2 in F-S system. The capability of forming starch-protein complex was assumed to be the major factor determining the properties of the gel.
According the observations of SEM, it was proposed that the protein layer matrix was developed prior to the gelatinization of starch during the heating process. The gelatinized starch might co-operate with the protein matrix in low starch/protein ratio system, and replaced protein as continuous phase in higher starch/protein ratio system.
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