Wheat Starch Gelatinization - the Effects of Sucrose, Emulsifier and the Physical State of the Emulsifier
| Main Authors: | , , |
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| Format: | Article |
| Language: | English Slovak |
| ISSN: | ISSN 0038-9056 |
| Online Access: | http://www.viks.sk/chk/star_3_4_03_150_161.doc |
| Abstract: | Summaries. The effect of emulsifier and/or sucrose on the swelling of an 8% wheat starch dispersion was evaluated by microscopy. Visual observations of smeared starch pastes under the light microscope, image analysis of the starch granule sizes and viscosity measurements of the starch paste during heating were combined to explain the effects of the added ingredients. Sucrose (12 or 24%, w/w) was shown to delay the swelling of the granules at least up to 50 °C. Above this temperature, the leakage of amylose and granule fragmentation were delayed, but the swelling itself seemed to be accelerated. The polyglycerol ester emulsifier (PGE/MG) at concentrations of 0.5 and 4.0% hindered amylose leakage completely up to 90 °C, followed by a sudden granule rupture. The size of the granules increased up to about 70 °C, but not above this temperature. The monoglyceride (MG) emulsifier in -form already had a restrictive effect on the swelling at low temperatures, while the same emulsifier in -form did not restrict the swelling until higher temperatures were reached. The emulsifier itself converted into the lamellar state at between 55 and 70 °C, irrespective of the initial form, but the final viscosity was higher in the paste with MG in B-form. Thus, the initial physical state of the emulsifier was shown to have an influence on the final properties of the gel. Conclusion. In this study it was shown that sucrose retarded the amylose leakage of wheat starch. It also caused an increase in the viscosity, because of a larger granule expansion at high temperatures. In combination with emulsifier, sucrose retarded the rupture of granules so that the viscosity increase also was delayed. Emulsifiers hindered amylose leakage completely until very high temperatures, followed by complete granular rupture. The swelling was restricted at low temperatures by a-gel emulsifiers, but not by p-crystalline emulsifiers, which influenced the final viscosity of the starch paste. The effect of the emulsifier was thought to be due to amylose-lipid complex formation. |
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| ISSN: | ISSN 0038-9056 |
