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" Preparation and properties of a thick -boiling, phosphorylated wheat starch for food use, and location of phosphate esters on starch by phosphorus-31-NMR spectroscopy "
S. T. Lim
P. A. Seib
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Latin Dissertation
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English
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| Record Number
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1112461
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TLpq303877270
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| Main Entry
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P. A. Seib
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S. T. Lim
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| Title & Author
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Preparation and properties of a thick -boiling, phosphorylated wheat starch for food use, and location of phosphate esters on starch by phosphorus-31-NMR spectroscopy\ S. T. LimP. A. Seib
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| College
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Kansas State University
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| Date
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1990
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| student score
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1990
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| Degree
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Ph.D.
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| Page No
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148
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| Abstract
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Wheat and corn starches were phosphorylated at various initial pH's by roasting at 130C for 2 h with 5% sodium tripolyphosphate (STPP) in the presence of 5% sodium sulfate. At pH 10, a wheat starch phosphate with 0.22% phosphorus (20% reaction efficiency) was obtained, which showed good thickening power and good stability of paste consistency. The best corn starch phosphate (0.16% P, 13% reaction efficiency) was obtained at an initial pH 11 with 5% STPP. Phosphorylation of starch below pH 9 with STPP showed almost totally monostarch phosphate; cross-linking was insufficient to stabilize the starch pastes. Wheat and corn starches were also phosphorylated with a mixture of 5% STPP and 2% sodium trimetaphosphate (STMP) in the presence of 5% sodium sulfate. The most viscous and shear-stable products were obtained at an initial reaction pH 9.5. However, phosphorylation using STMP with the two phosphate salts was extremely sensitive to pH, especially above pH 9.5. Paste clarity of the phosphorylated starches indicated cross-linking of starch with STMP began to accelerate rapidly above pH 8, but with STPP above pH 10. P-NMR spectroscopy was used to locate the phosphate esters on a wheat starch phosphate (D.S. 0.014) prepared by roasting the starch with 5% STPP in the presence of 5% sodium sulfate at an initial pH of 6. Spectra were measured on the usd\alphausd-limit dextrins and the usd\alphausd,usd\gammausd-limit phosphodextrins prepared from the starch phosphate using B. amyloliquefaciens usd\alphausd-amylase and A. niger glucoamylase. The P signals of several model compounds were recorded for comparison, including usd\alphausd-D-glucopyranose phosphates, methyl usd\alphausd-D-glucopyranoside phosphates and limit dextrins from amylose phosphate. It was concluded that the wheat starch phosphate had mainly C-6 and C-3 phosphate esters in a ratio of 2:3, and most substitution occurred along the linear segments of usd\alphausd-1,4 linked AGU's. The endogenous phosphate groups in potato starch also were detected on C-6 and C-3 in a ratio of 4:1. The P-NMR spectrum of the usd\alphausd-limit dextrin of potato starch showed the nonreducing end of the usd\alphausd-limit phosphodextrins contained all the 3-phosphate esters, but none of the 6-phosphate esters. The presence of 6-phosphate on the internal and the nonreducing AGU's in the usd\alphausd,usd\gammausd-phosphodextrin showed localized C-6 phosphorylation in potato starch, but isolated C-3 phosphorylation.
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Agricultural chemicals
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Biological sciences
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Food science
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Food science
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Phosphorus-31-NMR
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Pure sciences
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